Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED OFFICE ACTION
Specification
The disclosure is objected to because of the following informalities:
Paragraph [0006].
The paragraph recites that turning the supply current off and back on “will typically result in a long turn-on and turn-off times time for the optical signal.” The word “time” is duplicated, and the phrase should be corrected so that the sentence is grammatically complete and unambiguous.
Paragraph [0009].
The paragraph concludes with the phrase “or within the overall system).” The closing parenthesis has no corresponding opening parenthesis. The unmatched parenthesis should be removed or the sentence otherwise corrected.
Paragraph [0011].
The paragraph recites: “The energy recycling circuit electrically coupled to the switching circuit and is adapted to harvest at least a portion of energy from the bias current during the burst-off state.” The sentence omits the verb “is” before “electrically coupled.” Appropriate grammatical correction is required.
Paragraph [0015].
The paragraph recites that the circuit supply current is reduced as compared to a conventional burst-mode laser, “thereby reduces power of the burst-mode laser
driver.” The phrase “thereby reduces” is grammatically inconsistent with the preceding clause and should be corrected, for example, to “thereby reducing,” or otherwise rewritten without changing the originally disclosed subject matter.
Paragraph [0021].
The paragraph contains incomplete structural clauses. It recites that “[t]he switching circuit electrically is coupled to the driver circuit adapted to switch the bias current,” and that “[t]he energy recycling circuit electrically coupled to the switching circuit adapted to store at least a portion of energy.” The first clause lacks wording that clearly links the switching circuit to the recited switching function, and the second clause omits the verb “is” and a conjunction before “adapted.” The paragraph should be corrected so that the structural relationships and modifying phrases are grammatically clear.
Paragraphs [0024] and [0025].
The two consecutive paragraphs contain the same statement that the energy recycling circuit comprises at least one capacitor in parallel with the bias-current supply of the driver circuit. The duplicate paragraph appears to be an inadvertent repetition and should be deleted or otherwise corrected.
Paragraphs [0037] and [0042].
Paragraph [0037] recites “FIG. 5(b) a graph,” and paragraph [0042] recites “FIG. 9(b) a graph.” Each sentence omits the verb “is” after the figure designation. Appropriate grammatical correction is required.
Paragraph [0054].
The paragraph identifies Figure 3 as “a first example convention burst-mode laser driver.” The word “convention” should be corrected to “conventional.” The
paragraph also recites that “[a] voltage bias 316 is couples the dummy load 308 and laser 306 to ground in parallel.” The phrase “is couples” is grammatically incorrect and should be corrected.
Paragraph [0056].
The paragraph states that voltage sources 414a and 414b are provided for switching transistors 402a and 402b. Figure 4 and the same paragraph identify switch 404 as including transistors 404a and 404b; reference numerals 402a and 402b are not shown as switching transistors. The paragraph should be corrected to identify the proper transistor reference numerals. The paragraph also recites that “[a] voltage bias 416 is couples” the dummy load and laser to ground; the phrase “is couples” should be corrected.
Paragraph [0060].
Although the paragraph describes Figure 5(b), it identifies the simulated laser current, dummy-load current, and total power consumption as 502a, 504a, and 506a. Figure 5(b) and paragraph [0058] identify those Figure 5(b) traces as 502b, 504b, and 506b. The paragraph should be corrected to use the Figure 5(b) reference numerals consistently.
Paragraph [0063].
The paragraph identifies Figure 7 as “another convention burst-mode laser driver.” The word “convention” should be corrected to “conventional.” The paragraph also recites that “[a] voltage bias 716 is couples the dummy load 708 and laser 706 to ground in parallel.” The phrase “is couples” is grammatically incorrect and should be corrected.
Paragraph [0065].
The paragraph contains several inconsistent or erroneous expressions. The phrase “current course 802” should be corrected to “current source 802.” The paragraph states that transistor 804a is electrically coupled with energy recycling circuit 410, although the Figure 8 energy recycling circuit is identified as circuit 810. The paragraph also recites that “[a] voltage bias 816 is couples” the dummy load and laser to ground; the phrase “is couples” should be corrected. In addition, paragraph [0065] states that Ibias is 9.1 mA, whereas Figure 8 expressly labels Ibias as 6.3 mA. The numerical inconsistency must be resolved based on the originally filed disclosure without introducing new matter.
Paragraph [0066].
The paragraph states that transistors 802a and 802b are switched to the burst-on state. Figure 8 and paragraph [0065] identify the switching transistors as 804a and 804b, while reference numeral 802 identifies the current source. The paragraph should be corrected to identify the proper transistor reference numerals.
Paragraph [0069].
The paragraph describes Figure 9(b) but identifies the total power consumption as 906a. Figure 9(b), paragraph [0067], and paragraph [0070] identify the Figure 9(b) total-power trace as 906b. The paragraph should be corrected to use reference numeral 906b consistently.
Paragraph [0070].
The paragraph states that the inventive driver 800 needs the current source to be 9.1 mA. Figure 8 expressly labels Ibias as 6.3 mA. This repeats the numerical inconsistency identified in paragraph [0065]. The specification should be corrected to state a single supported value consistently, without introducing new matter.
Appropriate correction is required. Any amendment to the specification must comply with 37 CFR 1.121 and must not introduce new matter.
Abstract
The Abstract of the Disclosure is objected to because the final sentence is grammatically incomplete. The Abstract recites: “The energy recycling circuit electrically coupled to the switching circuit and is adapted to harvest at least a portion of energy from the bias current during the burst-off state.” The sentence omits the verb “is” before “electrically coupled.” The sentence should be corrected to recite that the energy recycling circuit “is electrically coupled to the switching circuit and is adapted” to perform the stated function, or should otherwise be corrected without changing the originally disclosed subject matter.
Appropriate correction is required. Any amendment to the Abstract must comply with 37 CFR 1.121 and must not introduce new matter.
Claim Status
Claims 1-19 are pending in this application and are under examination in this Office Action. No claims have been allowed.
Drawings
The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore, the claimed limitations within claims 3 and 13 are not shown within the drawings, namely that harvested energy is discharged to "the general power supply of an optical network unit (ONU)" to apply at least a portion of the power necessary to operate the ONU. Figures 2, 4, and 8 show the energy recycling circuit within the burst-mode laser-driver circuit, but no figure shows an ONU general power supply, an electrical connection from the energy recycling circuit to such a power supply, or a discharge path by which stored energy is returned to an ONU power rail. Nor is it shown, as mentioned within claims 7 and 17, that the claimed driver or system is adapted for upstream communications in a
passive optical network (PON) utilizing time-division multiple access or time-division multiplexing. Figure 11 shows burst frames and a burst-enable signal, but none of Figures 1-11 identifies an ONU, an optical line terminal (OLT), an optical distribution network (ODN), a passive splitter, a shared upstream optical fiber, or multiple ONUs transmitting in allocated time slots. Nor is it shown, as mentioned within claims 8 and 18, an optical amplifier coupled with the laser and the switching circuit, or a bias-current path configured to switch the bias current to both the laser and the optical amplifier during the burst-on state. No optical amplifier is identified in Figures 1-11. Further, the controller expressly recited in claims 9 and 11 and the controller adjustment expressly recited in claim 16 are not shown. Figures 3, 4, 7, and 8 show voltage sources labeled Venable and switching transistors, and Figure 11 shows a burst-enable signal and changing Ibias levels, but no figure identifies a controller, shows the controller receiving the signal, shows a control connection from the controller to the switching circuit or current source, or shows the controller adjusting the bias current per burst frame based on the burst-on/burst-off time ratio. These feature(s) must be shown or the feature(s) canceled from the claim(s). No new matter should be entered.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as "amended." If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either "Replacement Sheet" or "New Sheet" pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Objections
Claims 1-3, 5, 8, 11-14, 16, 18, and 19 are objected to because of the following informalities:
Regarding claims 1 and 11,
the clauses reciting a switching circuit “electrically coupled to the driver circuit adapted to switch” and an energy recycling circuit “electrically coupled to said switching circuit adapted to harvest/store” omit a conjunction before “adapted.” The claims should be corrected so that the recited structural relationships and the component performing each function are grammatically clear.
Regarding claims 2, 3, 12, and 13,
the phrase “as to apply” should be corrected to “so as to apply” or otherwise rewritten for grammatical clarity. In addition, claims 12 and 13 refer to “the harvested energy,” whereas claim 11 introduces energy that is “stored.” The terminology should be made consistent with the claim from which claims 12 and 13 depend.
Regarding claim 5,
the phrase “thereby reduces power” is grammatically inconsistent with the preceding clause and should be corrected, for example, to “thereby reducing power,” without changing the scope of the claim.
Regarding claim 8,
the phrase “wherein said switching circuit further adapted” omits the verb “is” and should be corrected to read “wherein said switching circuit is further adapted.”
Regarding claim 14,
the preamble recites “The burst-mode laser driver according to claim 12,” although claim 12 is directed to a burst-mode laser system. The terminology should be made consistent with the claim from which claim 14 depends.
Regarding claim 16,
a comma is omitted after “claim 12.” For grammatical clarity, the claim should also recite “during the burst-off state” and “based on the burst-on/burst-off time ratio,” or otherwise provide the appropriate articles.
Regarding claim 18,
the preamble recites “The burst-mode laser driver according to claim 11,” although claim 11 is directed to a burst-mode laser system. Claim 18 also recites “wherein switching circuit is configured” without “the” or “said” before “switching circuit.”
Regarding claim 19,
the preamble recites “The burst-mode laser driver according to claim 11,” although claim 11 is directed to a burst-mode laser system. The phrase “wherein the laser to be driven is” should also be corrected for grammatical clarity, for example, to “wherein the laser is,” without changing claim scope.
Appropriate correction is required.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION. —The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claims 4-6, 14, and 15 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Regarding claim 4,
Claim 4 recites "at least one capacitor in parallel with the bias current supply of said driver circuit."
There is a lack of clear antecedent basis for "the bias current supply." Claims 1 and 2 introduce a "bias current," a "driver circuit," a "switching circuit," an "energy recycling circuit," and "the laser bias current," but neither claim introduces a structure identified as a bias current supply. The phrase "in parallel with" requires an identifiable structural referent having electrical terminals or nodes, yet the claims do not identify which structure constitutes the claimed supply. The ambiguity is not cured by the specification because Figure 4 and paragraph [0056] separately identify current source 402, Ibias, and voltage bias 416, while Figure 8 and paragraph [0065] separately identify current source 802, Ibias, and voltage bias 816. As written, it is unclear whether the capacitor must be connected in parallel with the current source, a voltage-bias supply, the driver-circuit power supply, the bias-current path, or another structure. Accordingly, the metes and bounds of claim 4 are not reasonably certain, and claim 4 is indefinite.
Regarding claim 5,
Claim 5 recites "said circuit supply current is reduced as compared to a conventional burst-mode laser, thereby reduces power of said burst-mode laser driver."
There is a lack of clear antecedent basis for "said circuit supply current." Claims 1 and 2 do not introduce a circuit supply current. Instead, claim 1 recites a bias current supplied to the burst-mode laser, and claim 2 recites a laser bias current necessary to bias the laser. The specification separately discusses driver supply current, current-source current, laser current, dummy-load current, and total power consumption. It is therefore uncertain which current must be reduced to satisfy the claim.
Further, the phrase "reduced as compared to a conventional burst-mode laser" does not provide an objective comparison standard. The claim compares a current to a device, rather than to a corresponding current of a defined conventional laser driver or system, and does not identify the conventional topology, burst duty cycle, supply voltage, required laser current, optical output, load, measurement interval, or whether the comparison concerns peak, average, source, laser, or total supply current. The disclosure presents materially different conventional examples: Figure 3 and paragraph [0054] identify a 50 mA current source, whereas Figure 7 and paragraph [0063] identify a 105 mA current source. The phrase "thereby reduces power of said burst-mode laser driver" does not cure the ambiguity because the claim does not identify which power is reduced or the operating conditions under which the reduction is determined. Accordingly, a person of ordinary skill cannot determine with reasonable certainty which current and which reference operating condition establish the claimed reduction, and claim 5 is indefinite.
Regarding claim 6,
Claim 6 recites "wherein the supply current is adapted per burst frame during burst-off state, immediately after a burst, based on a burst-on/burst-off time ratio."
There is a lack of clear antecedent basis for “the supply current.” Claim 6 depends from claim 2, not from claim 5, and neither claim 1 nor claim 2 introduces a supply current. Claim 1 introduces a bias current supplied to the burst-mode laser, and claim 2 introduces the laser bias current necessary to bias the laser. The specification, however, uses “supply current,” “circuit supply current,” “bias current,” and current-source current in different contexts. For example, paragraphs [0015] and [0016] refer to circuit supply current and supply current, while paragraphs [0075]-[0078] describe adapting Ibias based on burst duty cycle. As written, it is unclear whether the claim requires adaptation of the current-source output, the current supplied to the laser, the total driver supply current, the ONU supply current, or another current. The phrase “is adapted per burst frame” also does not specify whether the current is measured, selected, reduced, or otherwise changed. Because those quantities and operations may differ during burst-on, burst-off, charging, and discharging intervals, the ambiguity materially affects the scope of the claim. Accordingly, the metes and bounds of claim 6 are not reasonably certain, and claim 6 is indefinite.
Regarding claim 14,
Claim 14 recites "wherein said energy recycling circuit comprises at least one capacitor in parallel with the bias current supply of said driver circuit."
There is a lack of clear antecedent basis for "the bias current supply." Claim 14 depends from claim 12, which depends from claim 11. Claims 11 and 12 introduce a "bias current," a "driver circuit," a "switching circuit," an "energy recycling circuit," and "the laser bias current," but neither claim introduces a structure identified as a bias current supply. The phrase "in parallel with" requires an identifiable structural referent having electrical terminals or nodes, yet the incorporated claims do not identify which
structure constitutes the claimed supply. The ambiguity is not cured by the specification because Figures 4 and 8 and paragraphs [0056] and [0065] separately identify a current source, the current Ibias, and the voltage Vbias. It is therefore unclear whether the capacitor must be connected in parallel with the current source, a voltage-bias supply, the driver-circuit power supply, the bias-current path, or another structure. Accordingly, the metes and bounds of claim 14 are not reasonably certain, and claim 14 is indefinite.
Regarding claim 15,
Claim 15 recites "wherein said bias current is reduced as compared to a conventional burst-mode laser."
The phrase "reduced as compared to a conventional burst-mode laser" fails to provide an objective boundary for the claimed reduction. The claim compares a bias current to a laser device rather than to a corresponding current of a defined conventional burst-mode laser driver or system. The claim does not identify whether the relevant bias current is a peak current, average current, current-source output, laser current, or total supply current; does not identify a conventional reference topology; and does not require the comparison to be made at the same required laser current, optical output, burst duty cycle, supply voltage, temperature, load, or timing condition.
The intrinsic record does not supply a single objective benchmark. Figures 3 and 7 disclose different conventional circuits having stated current sources of 50 mA and 105 mA, respectively, and the claim does not identify which conventional circuit or operating point controls the comparison. Consequently, a person of ordinary skill cannot determine with reasonable certainty whether a particular system satisfies the claimed reduction. Accordingly, the metes and bounds of claim 15 are not reasonably certain, and claim 15 is indefinite.
Accordingly, claims 4-6, 14, and 15 are indefinite under 35 U.S.C. 112(b).
Claim Rejections – 35 U.S.C. § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for the obviousness rejections set forth in this Office Action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
As reiterated by the Supreme Court in KSR, and as set forth in MPEP 2141 (R-01.2024), II, the factual inquiries of Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), applied for establishing a background for determining obviousness under 35 U.S.C. §103, are summarized as follows:
Determining the scope and content of the prior art;
Ascertaining the differences between the prior art and the claims at issue;
Resolving the level of ordinary skill in the pertinent art; and
Considering objective evidence indicative of obviousness or non-obviousness, if present.
Each patent document relied upon below was publicly available before the September 19, 2024 effective filing date of the claimed invention and is applied as prior art under AIA 35 U.S.C. 102(a)(1).
For claims also rejected under 35 U.S.C. 112(b), the prior-art analysis is made solely for examination purposes using the reasonable interpretations expressly stated below and does not withdraw or cure the indefiniteness rejection.
Claims 1, 2, 4, 9, 11, 12, and 14 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. (US20160191196A1) in view of Crawford (US6697402B2).
Claim 1
Troiani teaches the burst-mode laser-driver architecture recited in claim 1, including a laser driver, a laser, a bias-current source, burst-on and burst-off states, and a switching path that keeps the bias active while steering current away from the laser during burst-off.
Troiani identifies the claimed burst-mode environment: “One such application is burst mode communication systems which assign timeslots to various users of a shared optical cable and then each user transmits in bursts during their assigned time slot. As can be appreciated, rapid response time allows an assigned user to begin transmitting sooner and terminate transmission faster, during their assigned time slot, translates to higher effective data rates during the time slot. Therefore, there is a need in the art to reduce burst-on time and burst-off time.” [Troiani, ¶ [0005]].
Regarding the claimed driver circuit adapted to be electrically coupled to a burst-mode laser and configured to control a bias current supplied to the laser, Troiani discloses a driver that receives a modulation input, a laser or other optical signal generator, and a bias-current source connected to the laser-current path.
Troiani teaches the driver structure: “The driver includes a differential pair with a first transistor configured to receive a first input signal and a second transistor configured to receive a second input signal. The first signal and the second signal being a differential input signal such that the differential pair is configured to supply a first drive signal and a second drive signal in response to the first input signal and the second input signal.” [Troiani, ¶ [0006]].
Troiani further teaches the laser and bias-current connection: “The anode terminal of the optical signal generator connects to a supply voltage node 242 through the inductor 250. At the cathode terminal 260, the optical signal generator 256 connects to the inductor 252,
which in turn connects to a switch 225 and a bias current source 268 as shown.” [Troiani, ¶ [0040]; FIG. 2A].
Regarding the switching circuit electrically coupled to the driver circuit and adapted to switch the bias current between the laser during burst-on and a dummy electrical path during burst-off, Troiani expressly teaches switch S2 at the laser-bias node and teaches steering the maintained bias current away from the laser during burst-off.
Troiani states: “The switch S2 225 is connected between a node formed by the inductor 252 and the bias current source 258, and at an opposing terminal to the supply voltage node 242. The switch S2 225 receives a control input C2 which controls the switch position between an open and closed position. The switch S2 225 shorts the voltage across the light source 256 to rapidly prevent light output during burst-off periods. In other embodiments, the switch S2 may be replaced with any device configured to steer the bias current and the modulation current away from the laser during burst-off periods.” [Troiani, ¶ [0049]; FIG. 2A].
Troiani further explains the non-lasing shunt or dummy path: “During burst off, any configuration or element can be employed that prevents device current from going into the optical module, such as the laser 256. The switches S1, S2 are shown for enablement and understanding. Thus, any device that, when the bias is active, shunts bias current to the supply to keep it away from the laser can be employed for the reasons stated herein. In one or more embodiments, this could be a switch, or a diff. pair, any active device, such as a FET or transistor, or any other device or means to turn off the bias modulation. The purpose of such a device is to establish the bias, which is a constant current to the laser, when in burst off, to rapidly be effectively zero current to laser. In certain example environments of use, such a TDM system, any current leakage causes the laser to pollute the fiber, which in turn reduces the SNR for other users. Using this innovation, the system is able to maintain the bias on, but use the switch (or other element) to rapidly shunt the current away from the laser to keep the laser off.” [Troiani, ¶ [0052]].
Troiani therefore teaches the driver circuit, laser, bias current, burst-state control, and switching of the maintained bias current between a lasing path and a non-lasing shunt path.
Troiani does not expressly store and recycle energy from that shunted current. However, within analogous art, Crawford supplies the energy-recycling structure in a laser-driver circuit having the same functional event: the laser is turned off by closing a shunt path while current and stored electrical energy are retained, circulated, or returned to storage instead of being dissipated.
Crawford teaches a laser-diode driver having an energy-storage element, a laser switch, and a shunt switch: “According to the invention, a diode array driver is connected between a power supply and a diode array. An input of the driver receives power from the power source. An output of the driver delivers power to the diode array. The driver comprises an energy storage inductor between the power supply and an end of the diode array, for storing energy. A switching element is connected between the other end of the diode array and ground. A shunt switch is connected across the diode array. When the shunt switch is opened, energy stored in the inductor is suddenly delivered to the diode array. A diode may be connected between the other end of the diode array and the input of the driver.” [Crawford, col. 2, ll. 8-20; FIG. 1].
Crawford expressly teaches recycling energy when the laser pulse is terminated by the shunt switch: “In use, a first switch is turned on to build up current in the inductor just prior to the laser pulse. During this period, the load (diode array) is shorted out by a second (shunt) switch in series with the first switch. When the desired peak current is reached, the second switch is turned off (opened). Because current flow in an inductor can not change abruptly, the current continues to flow into the load, generating a high voltage, as required, to overcome the reactance of the load and leads. To turn off the pulse, the second switch is turned on, shorting out the load and discharging the lead/load inductance as the falling edge of the pulse. Simultaneously, the first switch is turned off and the energy stored in the series inductor is recycled back into the storage capacitor through a diode.” [Crawford, col. 2, ll. 50-63].
Crawford also teaches that, with the shunt path active during the laser-off interval, the remaining current and energy circulate in a low-impedance storage loop rather than being
immediately lost: “To end the pulse, the shunt switch 116 is once again closed, quickly dissipating the current in the diode array 110 in a closed loop that includes the shunt switch 116 and the diode array 110. If at the same time, the grounding switch 118 is opened, the current in the series inductor 108 circulates through a closed loop comprising the series inductor 108, the shunt switch 116 and the diode 122. In very high pulse rate applications, a substantial portion of the energy stored in the series inductor 108 may not have completely dissipated at the end of the pulse (when the shunt switch 116 is closed). Due to relatively low impedance of the circuit loop comprising the series inductor 108, the shunt switch 116 and the diode 122, with the grounding switch 118 open this energy will recirculate within the aforementioned loop as a loop current, dissipating slowly. This current can be “refreshed” to a desired level by periodically briefly closing the grounding switch 118. This energy storage capability further reduces the requirements on the power supply, permitting smaller size and cost.” [Crawford, col. 5, ll. 25-45; FIG. 1].
In the proposed combination, Crawford’s series energy-storage inductor, return diode, and storage capacitor are incorporated into Troiani’s already-switched laser-bias path. Troiani’s switch continues to route the maintained bias current to the laser during burst-on and away from the laser during burst-off. When the burst-off signal closes the non-lasing shunt path, the current associated with that path is carried by Crawford’s low-impedance inductor/shunt/diode loop and at least part of its electrical energy is retained in the inductor or returned through the diode to the storage capacitor. The combined structure is therefore an energy-recycling circuit electrically coupled to the switching circuit and adapted to harvest at least a portion of energy associated with the bias current during the burst-off state.
The combination does not require treating Crawford’s pulse current as inherently identical to Troiani’s bias current. Rather, Troiani supplies the claimed maintained bias current and burst-state switching, and Crawford supplies a known laser-driver implementation for conserving the electrical energy in the current path when the laser is shunted off. Applying Crawford’s implementation to Troiani’s bias-current path causes the current being switched by Troiani to be the current whose energy is circulated or returned to storage.
Troiani expressly identifies the problem addressed by the modification: “The cathode termination resistor, which connects to the cathode terminal and to a high voltage, creates a current path for laser bias current which may be sourced by a bias current driver. Therefore, some portion of the bias current is wasted in the termination resistor. This is undesirable in all applications, but in systems which rely on battery power for operation, is highly undesirable.” [Troiani, ¶ [0004]].
One of ordinary skill in laser-driver circuitry would have been motivated to replace or augment Troiani’s dissipative burst-off shunt path with Crawford’s energy-retaining shunt loop because both references address rapid laser turn-off, current steering, efficiency, and power-supply loading in laser drivers. Crawford expressly teaches that the off-state shunt loop preserves current energy and reduces power-supply requirements, while Troiani expressly identifies wasted bias current as undesirable. The references use compatible current sources, laser loads, inductors, electronic switches, diodes, capacitors, and supply nodes.
The modification would have predictably retained Troiani’s fast burst-on and burst-off response while recovering energy that otherwise would be dissipated in the non-lasing path. It would not change the basic principle of either reference: Troiani would still switch the laser bias according to the burst state, and Crawford’s recovery network would perform its known function at laser turnoff. Accordingly, the combination teaches or renders obvious every limitation of claim 1, and claim 1 would have been obvious.
Claim 2
With respect to claim 2, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 2 further requires the harvested energy to be discharged to the driver circuit during burst-on so as to provide at least a portion of the laser bias current necessary to bias the laser.
However, within analogous art, Troiani teaches reconnecting a charged capacitor and the supply rail to the driver when a new burst begins: “At a step 312, the controller receives
instructions, such as a trigger signal to initiate a burst-on period. In response, the controller generates switch control signals. At a step 316, the control signal is provided to switch S2 to
enable the laser (light source) and a short time thereafter, the controller provides a control signal to switch S1 to close switch S1. Closing switch S1 couples the capacitor and Vdd to the driver.” [Troiani, ¶ [0058]; FIG. 3].
Crawford teaches that the recovered-energy capacitor forms part of the laser-driver power supply: “FIG. 1 is a schematic diagram of an embodiment of a diode array driver 100, according to the invention. A storage capacitor 106 is charged to a desired voltage by a voltage source 102 and a diode 104. For the purposes of the present invention, the capacitor 106, voltage source 102 and diode 104 may be considered to be a power supply. It will, however, become apparent that an integrated system comprising both the driver and at least the storage capacitor of the power supply is advantageously supplied as a single unit, for driving an array of laser diodes.” [Crawford, col. 4, ll. 11-24; FIG. 1].
Crawford further teaches delivering stored inductor current to the laser when the shunt is opened for the next pulse: “The current monitor 120 monitors this current. When the current monitor indicates that the current has reached a desired level, the shunt switch 116 is opened. As a result, the voltage across the diode array 110 immediately jumps up to the level required to rapidly force the current from the series inductor 108 through the diode array 110. This results in a very short pulse rise time.” [Crawford, col. 5, ll. 22-27].
In the combined circuit, the energy retained in Crawford’s inductor/shunt loop or returned to storage capacitor 106 during Troiani’s burst-off state remains at the driver power-supply node. At the next burst-on transition, Troiani’s controller opens the laser shunt and couples the charged supply capacitor and Vdd to the driver, while Crawford’s retained inductor current is directed into the laser path. The retained or returned energy therefore contributes to the electrical current delivered through the driver to establish the laser bias; the external source need not provide the entire burst-on energy anew. The combined circuit accordingly discharges recovered energy to the driver during burst-on so as to provide at least a portion of the laser-bias current.
A skilled artisan would have been motivated to use the recovered energy in the next burst because this is the express operating purpose of Crawford’s storage and recirculation arrangement and directly complements Troiani’s controlled reconnection of a charged capacitor at burst-on. The result is reduced peak supply demand and faster establishment of the next laser current, with a reasonable expectation of success. Claim 2 would therefore have been obvious.
Claim 4
For purposes of prior-art examination only, and without withdrawing the § 112(b) rejection, “the bias current supply” is interpreted as the driver supply node that provides electrical energy to the bias-current source and the laser-driver circuit.
With respect to claim 4, all limitations of claim 2 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 4 additionally requires at least one capacitor in parallel with the interpreted bias-current supply.
However, within analogous art, Crawford expressly identifies capacitor 106 as an energy-storage component of the driver power supply: “A storage capacitor 106 is charged to a desired voltage by a voltage source 102 and a diode 104. For the purposes of the present invention, the capacitor 106, voltage source 102 and diode 104 may be considered to be a power supply.” [Crawford, col. 4, ll. 11-17; FIG. 1].
As shown in Crawford’s Figure 1, storage capacitor 106 is connected from the power-supply output node to ground, across the rail from which the series inductor and laser driver are energized. Under the stated reasonable interpretation, that capacitor is electrically in parallel with the driver supply. Troiani additionally places capacitor 240 at supply node 242 and selectively couples it to the driver through switch S1. The cited combination therefore teaches the claimed capacitor placement.
One of ordinary skill would have been motivated to connect the recovery capacitor across the driver supply because that is Crawford’s disclosed arrangement for accepting returned energy, supplying pulse current, stabilizing the supply node, and making recovered energy available for
the next laser activation. This is a known electrical placement used for its established function. Claim 4 would therefore have been obvious.
Claim 9
With respect to claim 9, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 9 further requires a controller configured to receive a signal and to switch the switching circuit between burst-on and burst-off based on the value of the signal.
However, within analogous art, Troiani expressly teaches signal-responsive burst-state control: “The first control signal and second control signal may be generated by a controller responsive to a burst-on signal or a burst-off signal. Responsive to a burst-on signal, the second control signal opens the second switch and thereafter the first control signal closes the first switch. In one configuration responsive to a burst-off signal, the first control signal opens with first switch to thereby maintain charge on the charge storage device, and thereafter the second control signal closes the second switch.” [Troiani, ¶ [0009]].
Troiani further states: “The controller 220 receives and processes a status input to generate the one or more control signals C1, C2, C3 provided to the switches. In one embodiment, the status input comprises information regarding whether the driver and light source is in burst-on mode or burst-off mode.” [Troiani, ¶ [0050]; FIG. 2A].
These disclosures teach a controller that receives a signal whose value identifies burst-on or burst-off and, according to that value, opens and closes the switching elements that route current to the laser or to the non-lasing recovery path. The additional limitation is therefore expressly taught.
A skilled artisan would have used Troiani’s controller to coordinate Crawford’s recovery switches because both references require ordered switching at laser turnoff and turn-on. Coordinated control prevents unwanted laser emission, preserves stored energy, and avoids conflicting switch states. Claim 9 would therefore have been obvious.
Claim 11
Troiani teaches the burst-mode laser, driver circuit, bias-current source, controller, modulation function, and signal-responsive switching structure recited in claim 11, while
Crawford teaches storing and recycling energy from the laser-current path when the laser is switched off.
Troiani teaches the controller and burst-state signal: “The controller 220 receives and processes a status input to generate the one or more control signals C1, C2, C3 provided to the switches. In one embodiment, the status input comprises information regarding whether the driver and light source is in burst-on mode or burst-off mode.” [Troiani, ¶ [0050]; FIG. 2A].
Troiani teaches modulation of the optical source by the driver: “Modulation signals, which define the signal to be generated as an optical signal, [are] presented to the base nodes of transistor 270, 272 as differential signals. These signals are presented at the collector node of the transistor 270, 272 and presented to the light source to drive the light source.” [Troiani, ¶ [0051]].
Troiani teaches switching the bias and modulation current away from the laser during burst-off: “The switch S2 225 shorts the voltage across the light source 256 to rapidly prevent light output during burst-off periods. In other embodiments, the switch S2 may be replaced with any device configured to steer the bias current and the modulation current away from the laser during burst-off periods.” [Troiani, ¶ [0049]].
Crawford teaches the corresponding energy-storage operation during the laser-off interval: “If at the same time, the grounding switch 118 is opened, the current in the series inductor 108 circulates through a closed loop comprising the series inductor 108, the shunt switch 116 and the diode 122. In very high pulse rate applications, a substantial portion of the energy stored in the series inductor 108 may not have completely dissipated at the end of the pulse (when the shunt switch 116 is closed). Due to relatively low impedance of the circuit loop comprising the series inductor 108, the shunt switch 116 and the diode 122, with the grounding switch
118 open this energy will recirculate within the aforementioned loop as a loop current, dissipating slowly.” [Crawford, col. 5, ll. 29-40].
In the proposed system, Troiani’s controller receives the burst-state signal and routes the bias current between the laser and the non-lasing path. Crawford’s energy-storage inductor, diode,
and storage capacitor are coupled to that switching path so that, upon entry into burst-off, at least part of the electrical energy associated with the current is stored or recirculated instead of being dissipated. The combination therefore teaches the burst-mode laser system, controller, driver, modulation, switch, dummy path, and energy-storage limitations of claim 11.
One of ordinary skill would have combined the references for the same reasons stated for claim 1, with the additional recognition that Troiani already provides the controller expressly required by claim 11. Using that controller to sequence Crawford’s recovery path would synchronize emission cutoff, current diversion, and energy storage. The result would have been predictable, and claim 11 would have been obvious.
Claim 12
With respect to claim 12, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 12 further requires that the stored energy be discharged to the driver circuit during burst-on to provide at least a portion of the laser bias current.
However, within analogous art, Crawford teaches returning off-state energy to the storage capacitor: “Simultaneously, the first switch is turned off and the energy stored in the series inductor is recycled back into the storage capacitor through a diode.” [Crawford, col. 2, ll. 59-63].
Troiani teaches coupling the charged capacitor to the driver at burst-on: “At a step 316, the control signal is provided to switch S2 to enable the laser (light source) and a short time thereafter, the controller provides a control signal to switch S1 to close switch S1. Closing switch S1 couples the capacitor and Vdd to the driver.” [Troiani, ¶ [0058]].
Thus, in the proposed combination, energy returned by Crawford to storage capacitor 106 during burst-off forms part of the driver supply and is discharged into the laser-current path when Troiani’s controller initiates the next burst. That recovered energy contributes at least a portion of the current delivered through the driver to establish laser bias. Reuse in the next
operating cycle is the expected function of Crawford’s recovery capacitor and Troiani’s burst-on capacitor coupling. Claim 12 would therefore have been obvious.
Claim 14
For purposes of prior-art examination only, and without withdrawing the § 112(b) rejection and claim objection, claim 14 is interpreted as a system claim, and “the bias current supply” is interpreted as the driver supply node that provides electrical energy to the bias-current source and the laser-driver circuit.
With respect to claim 14, all limitations of claim 12 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 14 additionally requires a capacitor in parallel with that supply.
Crawford’s Figure 1 and column 4, lines 11-24, teach energy-storage capacitor 106 connected across the output of the driver power supply and ground. Under the stated interpretation, the capacitor is in parallel with the driver supply and is the destination for recycled energy.
Troiani teaches a capacitor at the driver supply node and a switch that selectively couples that capacitor to the driver: “The opposing terminal of the switch S1 224 connects to capacitor 240, which in turn connects to the voltage supply node 242 as shown.” [Troiani, ¶ [0048]; FIG. 2A].
The capacitor across the high-voltage supply and ground is in parallel with the driver supply, and Troiani’s capacitor is connected at the same supply node for selective discharge into the driver. The combined system therefore contains the claimed capacitor arrangement under the stated interpretation.
One of ordinary skill would have been motivated to use this parallel capacitor arrangement because a burst-mode laser requires a low-impedance local energy reservoir for high transient
current, and the same capacitor provides a natural destination for recovered energy. Crawford expressly uses the capacitor for pulse energy and recharge, while Troiani selectively couples the capacitor to the driver. The arrangement is a known circuit implementation serving its ordinary function, and claim 14 would therefore have been obvious.
Claims 5 and 15 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. in view of Crawford, and further in view of Ikram et al. (US20070286609A1).
Claim 5
For purposes of prior-art examination only, and without withdrawing the § 112(b) rejection, “circuit supply current” is interpreted as the average current drawn by the burst-mode driver from its supply, and the comparison is interpreted as a reduction relative to a conventional burst-mode driver that maintains or dissipates a larger current during burst-off.
With respect to claim 5, all limitations of claim 2 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 5 additionally requires reduced circuit supply current and reduced driver power relative to a conventional burst-mode arrangement.
Troiani identifies the conventional loss: “The cathode termination resistor, which connects to the cathode terminal and to a high voltage, creates a current path for laser bias current which may be sourced by a bias current driver. Therefore, some portion of the bias current is wasted in the termination resistor. This is undesirable in all applications, but in systems which rely on battery power for operation, is highly undesirable.” [Troiani, ¶ [0004]].
Ikram teaches reducing the current drawn by the bias function outside the transmit window: “As a result of this mode of operation, the power consumptions may be reduced during times other than the transmit window by reducing the current draw from the biasing function, namely from the driver 2812 biased by the amplifier(s) 2824. However, by leaving one or more amplifiers active during times other than the transmit window, the time to restore full biasing power is reduced and glitching or surging is minimized.” [Ikram, ¶ [0200]].
Ikram teaches burst-enable control of the current-mirror ratio and resulting current draw: “As configured herein, the current mirror is ratioed based on the ratio of MX device 3048 and the devices 3042 and 3044. When the switch 3040 is closed, the ratio between devices 3048 and 3044, 3042 is (3X+1X):MX. When the switch 3040 is open, then the ratio is 1X:MX. The value M may comprise any whole number. As can be appreciated, the switch position determines
the ratio of the current mirror, which in turn determines the current draw of the current mirror and the biasing current provided to node 3018. The switch is controlled by a switch control signal which may be the same as or related to the burst/transmit enable signal BEN 3020. Vcc supplies the supply voltage to the bias circuit 3036 as shown. During transmit windows, the switch is open. During wait windows, when the laser is not transmitting, the switch is closed.” [Ikram, ¶ [0212]].
Troiani and Ikram reduce the current drawn during the non-transmit interval, while Crawford recirculates or returns energy that otherwise would be dissipated at laser turnoff. The combined driver therefore draws less average current from the external supply and consumes less power than the conventional full-current shunt or termination arrangement identified by Troiani. This teaches the claim under the stated interpretation.
One of ordinary skill would have been motivated to combine Ikram’s selectable low-current wait-window operation with the Troiani/Crawford recovery driver because the wait window can dominate the operating cycle and because off-state current and turnoff-energy loss are complementary sources of power consumption. The combination would predictably reduce supply current, heat, and battery demand while preserving a limited active bias path for rapid burst-on. Claim 5 would therefore have been obvious.
Claim 15
For purposes of prior-art examination only, and without withdrawing the § 112(b) rejection, the phrase “bias current is reduced as compared to a conventional burst-mode laser” is interpreted as requiring a lower burst-off or average bias current than a conventional burst-mode arrangement that maintains a larger bias current during the non-transmit interval.
With respect to claim 15, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein claim 15 additionally requires the bias current to be reduced relative to a conventional burst-mode laser.
Ikram supplies the additional reduced-bias limitation.
Ikram explains the timing-dependent current selection: “The architecture can be used for more/less power saving with different burst-on/off times for different applications. Any ratio between on and off current can be used and should be selected in such a way to satisfy the burst-on requirements of the system. The laser 3004 may optionally be a low power laser. The laser 3004 may be used in a burst mode PON system.” [Ikram, ¶ [0219]].
Ikram states the resulting benefit: “This solution realizes power savings during burst-off with fast burst-on/off times. This is significant because in certain applications the duration of the burst off period (wait window) is many times greater than the burst transmit period (transmit window).” [Ikram, ¶ [0220]].
The combined system uses Troiani’s burst-state controller, Ikram’s reduced off-state bias-current operating point, and Crawford’s energy recovery. It therefore has a lower burst-off and average bias current than a conventional system that keeps the larger current active throughout the wait window.
A skilled artisan would have adopted Ikram’s reduced-current state because Ikram expressly teaches power savings while retaining fast burst response, and Crawford’s recovery network further reduces the external energy demand without interfering with the selected bias level. Claim 15 would therefore have been obvious.
Claims 3 and 13 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. in view of Crawford, and further in view of Khotimsky et al. (US20180048477A1).
Claim 3
With respect to claim 3, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 3 further requires discharging the recovered energy to the general power supply of an optical network unit so as to provide at least a portion of the power required to operate the ONU.
However, within analogous art, Crawford expressly teaches returning residual laser-driver energy to the power supply and integrating the storage capacitor with the driver: “Means may be provided for returning residual energy stored in the inductor back to the power supply. An overall system comprises the diode array driver(s) and at least a portion of the power supply namely, an energy storage capacitor.” [Crawford, col. 2, ll. 29-38].
Khotimsky teaches the claimed PON/ONU environment and the ONU’s general source of operating power: “A PON system can include a central node, called an optical line terminal (OLT), which can be in connection with a single or multiple user nodes called ONUs via a passive optical distribution network (ODN). An OLT can be located at the access provider’s communication facility (e.g., central office). An ONU can be located at or near the access user’s premises. An ONU typically draws electrical power from the user’s premises power supply network and may employ battery backup to support communication services in case of power outage.” [Khotimsky, ¶ [0003]].
Khotimsky further identifies the system-level reason to conserve that ONU power: “Method and apparatus are disclosed that, in one beneficial aspect, are useful to reduce the power consumption of an optical network unit in a PON. Implementations described in this document can provide several advantages. For example, the disclosed techniques can allow an access provider to guarantee lifeline services to customers by increasing the duration of operational time during power outages. The techniques can also be used to reduce the size
and cost of the battery backup unit, reduce overall greenhouse gas emission and carbon footprint of the information and communication technologies based on passive optical networks, and so on.” [Khotimsky, ¶ [0005]].
Khotimsky also confirms that the ONU transmitter and receiver are electrical loads managed within the ONU’s overall power architecture: “At 802, method 800 operates an ONU in a first state in which a transmitter of the ONU is turned off and a receiver of the ONU is turned on. . . . At 804, method 800 operates the ONU in a second state in which both the transmitter and the receiver are turned off.” [Khotimsky, ¶¶ [0062]-[0063]; FIG. 8].
Neither Crawford nor Khotimsky uses the exact phrase “general power supply” for the proposed connection. Crawford nevertheless expressly returns recovered laser-driver energy to the power supply, while Khotimsky expressly places the optical transmitter within an ONU powered from a general ONU power source. In the proposed combination, the Troiani/Crawford burst-mode laser driver is used as the ONU transmitter driver and Crawford’s recovered-energy return is connected to the ONU’s common supply input or regulated supply rail rather than to an isolated dissipative load. Energy returned to that rail offsets energy drawn by the ONU transmitter, receiver, controller, or other circuitry and therefore supplies at least a portion of the power required to operate the ONU.
One of ordinary skill would have been motivated to make this connection because Crawford expressly teaches returning energy to the power supply, Khotimsky identifies reduction of total ONU and battery power as a design objective, and a common ONU rail allows recovered energy to be consumed wherever demand exists. The modification uses a known energy-return circuit for its established purpose and would predictably reduce net ONU power draw. Claim 3 would therefore have been obvious.
Claim 13
With respect to claim 13, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 13 adds the same requirement of discharging the stored energy to the general ONU power supply.
However, within analogous art, Crawford’s express return of residual energy to the power supply and Khotimsky’s ONU supplied from a general premises power network render the claimed system-level connection obvious for the reasons stated for claim 3. In the combined ONU, the recovered energy is returned to the common regulated rail that powers the transmitter and other ONU electronics, thereby providing part of the required operating power.
A skilled artisan would have made this connection to maximize utilization of recovered energy, reduce battery and supply demand, and avoid a separate dedicated load. The electrical
connection does not alter the optical or burst-control operation of the transmitter. Claim 13 would therefore have been obvious.
Claims 7, 10, 17, and 19 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. in view of Crawford, and further in view of Van Veen et al. (US20230107882A1).
Claim 7
With respect to claim 7, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 7 further requires adaptation for upstream communications in a PON using time-division multiple access.
However, within analogous art, Van Veen teaches the PON and upstream TDMA environment: “A passive optical network (PON) typically has a point-to-multipoint architecture in which one or more passive optical splitters are used to enable a single optical transmitter to broadcast data transmissions to multiple optical receivers. An example PON includes an optical line terminal (OLT) at the service provider’s central office (CO) and a plurality of optical network units (ONUs) near or at the individual end users, such as residences,
businesses, radio towers, etc. Downstream signals are usually broadcast to all ONUs or at least a group of ONUs. Upstream signals are routed using a multiple access protocol, e.g., time division multiple access (TDMA).” [Van Veen, ¶ [0003]; FIG. 1].
Van Veen further states: “An ONU in a PON may employ a burst-mode optical transmitter.” [Van Veen, ¶ [0004]].
Van Veen provides the collision-free upstream implementation: “Receiver 114 is configured to receive upstream optical signals from ONUs 1601-160N transmitted using one or more upstream carrier wavelengths. A suitable TDMA protocol executed using controller 118 is typically used to prevent collisions, at receiver 114, between the upstream signals generated by different ONUs 160n, where n=1, 2, . . . , N.” [Van Veen, ¶ [0026]; FIG. 1].
Placing the Troiani/Crawford burst driver in the ONU transmitter of Van Veen and operating it during the ONU’s assigned upstream TDMA allocation teaches the additional limitation. Troiani already identifies time-slot burst communication over a shared optical cable, and Van Veen supplies the standard PON architecture.
A skilled artisan would have been motivated to use the energy-recycling driver in upstream TDMA PON operation because the repeated short transmit slots and longer idle intervals make rapid transitions and reduced off-state power particularly valuable. The use is directly within Troiani’s contemplated burst environment and would have produced predictable operation. Claim 7 would therefore have been obvious.
Claim 10
With respect to claim 10, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 10 additionally permits either a directly modulated laser or an externally modulated laser.
However, within analogous art, Van Veen expressly teaches both alternatives for a burst-mode PON transmitter: “In the corresponding TDM PONs and Time and Wavelength Division Multiplexing (TWDM) PONs, at least the upstream transmissions can be carried out in a burst mode. A burst-mode optical transmitter may employ a directly modulated laser (DML) or an
externally modulated laser (EML). In some literature, the acronym EML may also stand for “Electro-absorption Modulated Laser,” which is a particular type of externally modulated laser.” [Van Veen, ¶ [0017]].
Van Veen explains the DML alternative: “In a DML, data are placed on the optical beam by modulating the injection current, which may be directly applied to the laser-diode chip to generate a corresponding modulated optical signal.” [Van Veen, ¶ [0018]].
Van Veen explains the EML alternative: “An EML is typically implemented as a laser diode with an external optical modulator, e.g., typically an electro-absorption modulator (EAM). The laser diode section of an EML may be similar to that of a DML, but may be operated under a
(quasi) continuous-wave (CW) condition. The data signal is applied to the EAM section to generate a modulated optical signal.” [Van Veen, ¶ [0019]].
These disclosures expressly teach each alternative recited by claim 10. The energy-recycling circuit operates on the laser-bias path and is not dependent on whether data modulation occurs directly in the laser or in a separate electro-absorption modulator. Selection of DML or EML according to reach, speed, chirp, cost, and power requirements is a known transmitter design choice with predictable consequences. Claim 10 would therefore have been obvious.
Claim 17
With respect to claim 17, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 17 further requires upstream communications in a PON using time-division multiplexing.
However, within analogous art, Van Veen expressly identifies the claimed network: “The disclosed leveling may advantageously provide an effective tool for optimizing upstream transmission for high-speed time-division-multiplexing (TDM)-PONs.” [Van Veen, ¶ [0005]].
Van Veen further teaches: “In the corresponding TDM PONs and Time and Wavelength Division Multiplexing (TWDM) PONs, at least the upstream transmissions can be carried out in a burst mode.” [Van Veen, ¶ [0017]].
The cited disclosures place the Troiani/Crawford burst-mode laser system in an upstream TDM-PON and satisfy the additional limitation. A skilled artisan would have made this use because
upstream TDM-PON transmission is a standard environment requiring the rapid laser transitions and repeated off intervals addressed by the references. Claim 17 would therefore have been obvious.
Claim 19
For purposes of prior-art examination only, and without withdrawing the claim objection, claim 19 is interpreted as requiring the burst-mode laser system of claim 11 to employ a directly modulated laser or an externally modulated laser.
With respect to claim 19, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein claim 19 additionally requires the laser to be a directly modulated laser or an externally modulated laser.
However, within analogous art, Van Veen expressly teaches: “A burst-mode optical transmitter may employ a directly modulated laser (DML) or an externally modulated laser (EML).” [Van Veen, ¶ [0017]].
Van Veen illustrates an EML transmitter having a burst-mode laser-bias driver and controller: “As shown in FIG. 2, optical transmitter 164 comprises an EML including a laser diode 210 and
an EAM 220. An optical output signal 224 generated by EAM 220 can be directed, e.g., to optical circulator 162. Operational control of laser diode 210 and EAM 220 is carried out using an electronic controller 250 and driver circuits 230 and 240.” [Van Veen, ¶ [0032]; FIG. 2].
Van Veen also illustrates a DML transmitter: “As shown in FIG. 3, optical transmitter 164 comprises a DML 310 and a variable optical attenuator (VOA) 320. An optical output signal 324 generated using DML 310 and VOA 320 can be directed, e.g., to optical circulator 162. Operational control of DML 310 is carried out using an electronic controller 350 and driver circuits 330 and 340. Operational control of VOA 320 is carried out using electronic controller 350.” [Van Veen, ¶ [0035]; FIG. 3].
The cited reference therefore provides concrete DML and EML embodiments in the same burst-mode PON field. In the proposed combination, either Van Veen transmitter implementation is substituted for Troiani’s optical signal generator, while Troiani’s controller and burst-state
switch, together with Crawford’s recovery network, continue to act on the laser-bias path. One of ordinary skill would have selected a DML or EML according to ordinary reach, chirp, speed, cost, and power requirements because Van Veen expressly identifies both as burst-mode alternatives. The substitution changes only the known modulation implementation and would not interfere with the burst-state switching or energy-recovery function; therefore, it would have yielded predictable operation with a reasonable expectation of success. Claim 19 would have been obvious.
Claims 6 and 16 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. in view of Crawford, further in view of Ikram et al., further in view of Patterson (US4709416), and further in view of Budai (US8787415B1).
Claim 6
For purposes of prior-art examination only, and without withdrawing the § 112(b) rejection, “the supply current” is interpreted as the laser-bias current supplied by the driver/current-source circuitry. Claim 6 requires adjusting that current once per burst frame, during the burst-off interval immediately after the burst, based on the ratio of burst-on time to burst-off time.
With respect to claim 6, all limitations of claim 2 are taught or rendered obvious by Troiani and Crawford as set forth above, except that claim 6 additionally requires adapting the construed supply current once per burst frame, during burst-off immediately after the burst, based on the burst-on/burst-off time ratio.
However, within analogous art, Patterson supplies a per-burst adjustment immediately after transmission, Ikram supplies the timing-dependent relationship between burst-on and burst-off operation, and Budai supplies a controller implementation that calculates and adjusts a laser-bias duty cycle from on-time and cycle-period parameters.
Patterson teaches that the bias is updated in the off/dead interval immediately after each data transmission: “The arrangement of FIG. 10 operates in two generally similar modes. At initial
turn-on, or under control of a manual switch, the bias current is set to zero and then begins to increase until it reaches a predetermined level. Thereafter, in a second mode of operation, an adjustment is made towards the desired bias immediately following each data transmission.” [Patterson, col. 10, ll. 10-20; FIG. 10].
Patterson further summarizes the per-burst mechanism: “The bias current of the laser diode is adjusted following each data transmission, so that the light attributable to laser operation during the setting of bias is received during the dead time. The adjustment is accomplished by stepping an up-down counter by one clock pulse following transmission of each data burst.” [Patterson, Abstract; FIGS. 9-10].
Ikram teaches that the system distinguishes the burst-on transmit window from the burst-off wait window and knows their relative durations: “The time periods in which the generator 2816 is transmitting may be referred to herein as transmit windows. The time periods when the optic signal generator is not transmitting may be referred to herein as the wait window. In many example environments the wait window is longer than transmit window.” [Ikram, ¶ [0196]].
Ikram expressly teaches selecting current relationships for different burst-on and burst-off times: “The architecture can be used for more/less power saving with different burst-on/off times for different applications. Any ratio between on and off current can be used and should be selected in such a way to satisfy the burst-on requirements of the system.” [Ikram, ¶ [0219]].
Budai teaches controller generation of a PWM laser-bias current and identifies the timing quantities from which the duty cycle is determined: “the pulsed bias current source 112 can be operated/controlled by the controller 102 to produce a pulse width modulated (PWM) current signal at its output,” and the resulting signal has a duty cycle established by the pulse ON time and the cycle period; those parameters may be obtained from data stored in memory 102a or received through the controller interface. [Budai, col. 3, ll. 58-65; col. 4, ll. 1-16; FIG. 2].
Budai further teaches controller-directed adjustment and storage of the selected bias-current timing: “The procedure illustrated in FIG. 4 may be performed by the user under the direction of controller 102 executing suitable program code stored in memory 102a,” after which “the duty cycle can be further reduced” or increased until the desired laser characteristic is obtained, and the resulting settings can be stored in memory 102a. [Budai, col. 6, ll. 1-50; FIGS. 4 and 5A-5E].
The combined controller performs Patterson’s update once following each burst, while the system is in the immediately succeeding wait window. Ikram provides the known burst-on and burst-off timing relationship, and Budai provides controller-based selection of a bias-current duty cycle from the ON time and the total cycle period. These timing representations are
mathematically equivalent: if D = T_on/(T_on + T_off), then T_on/T_off = D/(1-D). Thus, the burst-enable or frame schedule already received by Troiani’s controller supplies T_on and T_off, and the controller uses those values to select the adjusted laser-bias current for the next frame. The combination therefore performs the claimed adjustment per burst frame, immediately after the burst during burst-off, based on the burst-on/burst-off time ratio.
One of ordinary skill would have been motivated to combine these teachings because the suitable off-state current is a known tradeoff between energy saving during the wait window and the current needed for rapid turn-on at the next burst. Ikram expressly states that different burst-on/off times call for different current relationships; Patterson teaches making the adjustment immediately after each burst so that it occurs during dead time; and Budai teaches a controller and stored timing parameters for calculating and adjusting laser-bias duty cycle while preserving the desired immediate turn-on characteristic. Implementing the selection in Troiani’s existing burst-state controller would have been a predictable digital-control use with a reasonable expectation of success. Claim 6 would therefore have been obvious.
Claim 16
For purposes of prior-art examination only, and without withdrawing the claim objection, claim 16 is interpreted as requiring the controller to adjust the laser-bias current after each burst, during the burst-off interval, according to the ratio of burst-on time to burst-off time.
With respect to claim 16, all limitations of claim 12 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein claim 16 additionally requires the controller to adjust the bias current once per burst frame, during burst-off immediately after the burst, based on the burst-on/burst-off time ratio.
However, within analogous art, Troiani expressly provides the controller and burst-state input, Patterson teaches an adjustment immediately following each data transmission, Ikram teaches selection according to different burst-on/off times, and Budai teaches controller-based calculation and adjustment of laser-bias duty cycle from ON-time and cycle-period parameters.
Troiani teaches the controller receiving the burst-state information: “The controller 220 receives and processes a status input to generate the one or more control signals C1, C2, C3 provided to the switches. In one embodiment, the status input comprises information regarding whether the driver and light source is in burst-on mode or burst-off mode.” [Troiani, ¶ [0050]].
Patterson teaches the required post-burst timing: “The bias current of the laser diode is adjusted following each data transmission, so that the light attributable to laser operation during the setting of bias is received during the dead time. The adjustment is accomplished by stepping an up-down counter by one clock pulse following transmission of each data burst.” [Patterson, Abstract; FIGS. 9-10].
Ikram teaches the timing-dependent selection criterion: “The architecture can be used for more/less power saving with different burst-on/off times for different applications. Any ratio between on and off current can be used and should be selected in such a way to satisfy the burst-on requirements of the system.” [Ikram, ¶ [0219]].
Budai teaches that controller 102 operates the bias-current source to produce a PWM bias current whose duty cycle is established by pulse ON time and cycle period, and teaches
controller-directed reduction or increase of that duty cycle with the selected timing stored in memory. [Budai, col. 3, ll. 58-65; col. 4, ll. 1-16; col. 6, ll. 1-50; FIGS. 2, 4, and 5A-5E].
A skilled artisan would have implemented Patterson’s per-burst update, Ikram’s timing-dependent current selection, and Budai’s controller-based duty-cycle calculation in Troiani’s controller because that controller already receives burst-state information and controls the current-routing switches. From the frame schedule, T_on and T_off are known; the claimed T_on/T_off ratio is directly and predictably derived from the duty cycle D = T_on/(T_on + T_off). Applying the new current setting immediately after the burst makes the selected off-state current effective throughout the wait window and leaves the active data burst undisturbed. The combination therefore teaches or renders obvious every additional limitation of claim 16, and claim 16 would have been obvious.
Claims 8 and 18 are rejected under 35 U.S.C. § 103 as being unpatentable over Troiani et al. in view of Crawford, and further in view of Ooi et al. (WO2018096522A1).
Claim 8
With respect to claim 8, all limitations of claim 1 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein Claim 8 additionally requires an optical amplifier coupled with the laser and switching the bias current to both the laser and the optical amplifier during burst-on.
However, within analogous art, Ooi teaches the claimed optical coupling: “SOA section 104 is positioned adjacent to LD section 102, separated by trench 110 extending partially through the layers associated with LD section 102 and SOA section 104, but optically coupled to LD section 102 via a shared waveguide to receive the laser output generated by LD section 102. The second terminal is utilized to provide a drive voltage to SOA section 104. The magnitude of the SOA drive voltage applied to the second terminal determines the magnitude of the
optical amplification provided to the received laser output generated by LD section 102.” [Ooi, ¶ [0025]; FIG. 1].
Ooi teaches a common source of electrical power for the laser and amplifier: “In one embodiment, a common power supply (not shown) is utilized to provide power to LD section 102 via the first terminal and SOA section 104 via the second terminal.” [Ooi, ¶ [0023]].
Ooi further teaches simultaneous current distribution: “The integrated SOA-LD device of claim 10, wherein the output of the integrated SOA-LD device is controlled using one or more power supplies, wherein a current divider can be used to split the driving current to provide a first drive current to the LD section and SOA section simultaneously when only one power supply unit is used.” [Ooi, claim 12].
In the proposed combination, Ooi’s optically coupled LD/SOA device and current-divider input are placed on the burst-on output of Troiani’s switching circuit. The switch therefore supplies
current to both the laser and optical amplifier during burst-on and routes current away from the active optical path into Crawford’s recovery path during burst-off.
One of ordinary skill would have been motivated to use Ooi’s integrated SOA-LD because an SOA is a known way to amplify laser output and Ooi expressly teaches common powering and simultaneous current distribution. Although Ooi illustrates a visible-wavelength device, the claim is not wavelength-limited, and the relied-upon electrical and optical relationships are applicable to the broadly claimed laser/amplifier structure. Placing the burst switch upstream of the current divider gives coordinated enable/disable control and a predictable amplified burst output. Claim 8 would therefore have been obvious.
Claim 18
For purposes of prior-art examination only, and without withdrawing the claim objection, claim 18 is interpreted as a burst-mode laser system that includes an optical amplifier coupled to the laser output and a switching circuit that supplies bias current to both during burst-on.
With respect to claim 18, all limitations of claim 11 are taught or rendered obvious by Troiani and Crawford as set forth above, except wherein claim 18 additionally requires an optical amplifier coupled to the laser output and a switching circuit configured to supply bias current to both the laser and the optical amplifier during burst-on.
However, within analogous art, Ooi teaches the additional optical-amplifier and simultaneous-current limitations.
Ooi teaches the optical-output relationship: “Based on the LD drive current, LD section 102 generates a laser output that is provided as an input to SOA section 104, which is optically coupled to LD section 102 via trench 110.” [Ooi, ¶ [0024]].
Ooi teaches separate electrical terminals supplied from a common source: “Integrated SOA-LD device 100 is a three-terminal device, with a first terminal providing an input to LD section 102, a second terminal providing an input to SOA section 104, and a third terminal for providing the grounding to the first and second terminals. In one embodiment, a common
power supply is utilized to provide power to LD section 102 via the first terminal and SOA section 104 via the second terminal.” [Ooi, ¶ [0023]].
The combined system places Ooi’s common-supply/current-divider arrangement on the laser side of Troiani’s burst switch. Troiani’s controller consequently enables both optically coupled sections during burst-on and diverts the current to Crawford’s non-lasing recovery path during burst-off. The modification retains the independent electrical control of the LD and SOA while coordinating their burst enable.
A skilled artisan would have used the same burst-state control for both sections to avoid a laser-on/amplifier-off mismatch, provide a defined amplified output during the assigned burst, and simplify current control. Ooi expressly provides the common-source architecture and
simultaneous drive, while Troiani provides the burst control. Claim 18 would therefore have been obvious.
It is noted that any citations to specific pages, columns, lines, or figures in the prior art references and any interpretation of the reference should not be considered to be limiting in any way. A reference is relevant for all it contains and may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art. See MPEP 2123.
Conclusion
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/MOHAMMED ABDELRAHEEM/Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635
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