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
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 2024-04-12 in compliance with the provisions of 37 CFR 1.97 has been considered by the examiner and made of record in the application file.
Claim Status
Claims 1- 8 are pending in this application and are under examination in this Office Action. No claims have been allowed.
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention
Claims 4 and 5 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention.
Regarding claim 4,
the claim is indefinite because it recites “the wavelength tunable light source unit” without antecedent basis. Claim 1 recites “a wavelength tunable laser apparatus” but does not introduce any “wavelength tunable light source unit.” Therefore, the metes and bounds of the claim are unclear. Further, claim 4 recites “a circulation power at which the phase of the wavelength … is circulated,” which is unclear because the claim does not define what it means for “the phase … to be circulated” (e.g., phase wrapping/modulo operation) or what constitutes “circulation power.”
Regarding claim 5,
the claim is indefinite because it recites “the silicon optical waveguide” without antecedent basis. Claim 1 does not introduce any “silicon optical waveguide,” and thus it is unclear what “silicon optical waveguide” is being heated or how it relates to the recited heater that controls a wavelength of the light output from the semiconductor optical amplifier by heating. Therefore, the metes and bounds of claim 5 are unclear.
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.
This application currently names joint inventors. In considering patentability of the claims, the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 C.F.R. § 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. § 102(b)(2)(C) for any potential 35 U.S.C. § 102(a)(2) prior art against the later invention.
Claims 1-3 and 8 are rejected under 35 U.S.C. §103 as being unpatentable over Yamazaki et al. (US20110013654A1) in view of Machida et al. (US20090022185A1) and Uesaka et al. (US9444221B2).
Claim 1
Yamazaki is directed to a wavelength variable laser device including a semiconductor optical amplifier and wavelength-variable sections on a planar Lightwave circuit (PLC). Yamazaki teaches a semiconductor optical amplifier and wavelength-variable laser structure, “The wavelength variable laser device according to the present invention is characterized to include: an optical filter formed in a planar Lightwave circuit; a semiconductor optical amplifier that Supplies light to the optical filter; a light reflecting section that returns the light transmitted through the optical filter to the semiconductor optical amplifier via the optical filter, optical waveguides which are formed in the planar Lightwave circuit and connect the semiconductor optical amplifier, the optical filter, and the light reflecting section; a wavelength variable section that changes a wavelength of the light transmitting through the optical filter, and a phase variable section that changes a phase of the light propagated on the optical waveguides…….[0023] The optical filter 12 is a multiple optical resonator that is formed by coupling three ring resonators 24, 25, and 26 having different optical path lengths from each other. The ring resonators 24, 25, and 26 are structured with optical waveguides formed on the PLC 11. The wavelength variable sections 17, 18, and 19 are film-like heaters which change the temperatures of the optical waveguides constituting the ring resonators 24, 25, and 26, respectively. The phase variable section 20 is a film-like heater which changes the temperature of the optical waveguide 16 that connects the optical filter 12 and the light reflecting section 14. [0024] The optical waveguide 16 is formed on the PLC 11 simultaneously with the ring resonators 24, 25, 26 and optical waveguides 15, 27, 28. The phase variable section 20 is also formed on the PLC 11 simultaneously with the wavelength variable sections 17, 18, and 19. With the wavelength variable laser device 10, phase controls of the light transmitting through the optical filter 12 is done not by the SOA 13 but by the phase variable section 20 that is provided additionally. However, as described above, the phase variable section 20 is formed simultaneously with other structural elements of the PLC 11, so that there is no increase in the number of manufacturing steps even when the phase variable section 20 is provided additionally. [0025] The light reflecting section 14 is a loop mirror constituted with the optical waveguide formed on the PLC 11. Thus, the light reflecting section 14 is also formed on the PLC 11 simultaneously with the ring resonators 24 and the like. The ring resonators 24, 25, 26 and the optical waveguides 15,27, 28 are optically coupled by directional couplers (not shown) ……….” [Yamazaki, ¶ [0017], ¶ ¶ [0023] - [0025]].
Yamazaki further teaches that wavelength-variable sections and phase-variable sections are implemented using film-like heaters that heat optical waveguides, “……. The wavelength variable sections 17, 18, and 19 are film-like heaters which change the temperatures of the optical waveguides constituting the ring resonators 24, 25, and 26, respectively. The phase variable section 20 is a film-like heater which changes the temperature of the optical waveguide 16 that connects the optical filter 12 and the light reflecting section 14 ……...” [Yamazaki, ¶ [0023] –¶ [0024]]
However, Yamazaki does not expressly teach a control unit that determines, based on the wavelength of the output light, a target value of heater power and a transition of the heater power until the target value is reached. However, in an analogous art, Machida teaches controlling a tunable semiconductor laser including a heater, including adjusting the heater heat value until it reaches a given value and correcting wavelength based on detected oscillation wavelength, “[0016] The present invention has been made in view of the above circumstances and provides a method of controlling a semiconductor laser that obtains a desired wavelength even if the heater is degraded. [0017] According to an aspect of the present invention, there is provided a method of controlling a semiconductor laser having a wavelength selection portion, a refractive index of the wavelength selection portion being controllable with a heater including: a starting sequence including a first step for adjusting a heat value of the heater until the heat value of the heater reaches a given value; and a wavelength control sequence including a second step for correcting a wavelength of the semiconductor laser according to a detection result of an oscillation wavelength of the semiconductor laser after the starting sequence……… [0027] The semiconductor laser 10 has a structure in which a SG-DBR region 11, a SG-DFB region 12 and a semiconductor amplifier (SOA: Semiconductor Optical Amplifier) region 13 are coupled in order. The SG-DBR region 11 has an optical waveguide in which gratings are provided at a given interval. That is, the optical waveguide of the SG-DBR region 11 has a first region that has a diffractive grating and a second region that is optically connected to the first region and acts as a spacer. The optical waveguide of the SG-DBR region 11 is composed of semiconductor crystal having an absorption edge wavelength at shorter wavelengths side compared to a laser oscillation wavelength. A heater 14 is provided on the SG-DBR region 11…...” [Machida, ¶ [0016], ¶ [0017], ¶ [0027]].
Further, Machida teaches determining a target value of electrical power to be supplied to the heater by obtaining the target value from a look-up table and then determining whether the electrical power to the heater is within a required range, “[0034] Then, the controller 50 determines whether the heat value of the heater 14 is within a required range according to an electrical power obtained with a voltage applied between both ends of the heater 14 and a current provided to the heater 14 (Step S3) ……………… [0035] If it is not determined that the heat value of the heater 14 is within the required range in the Step S3, the controller 50 corrects the temperature of the heater 14 (Step S7). The temperature of the heater 14 is corrected when the current provided to the heater 14 is changed and the electrical power obtained with the current provide do the heater 14 and the voltage applied between the both ends of the heater 14 is changed. After that, the controller 50 executes the Step S3 again. With the loop, the heat value of the heater 14 is feedback controlled so as to be within the required range. [0036] Next, the controller 50 determined whether the wavelength of the lasing light is within a required range according to the detection result of the wavelength detector 30 (Step S4) ………. [0038] If it is determined that the wavelength of the lasing light is within the required range in the Step S4, the controller 50 determines whether the optical intensity of the lasing light is within a required range (Step S5). In concrete, the controller 50 obtains the target value Im1 for feedback control from the look-up table 51, obtains the detection result Im1 of the light receiving element in the output detector 40, and deter mines whether the detection result Im1 is within a given range including the target value Im1 for feedback control. [0039]. If it is not determined that the optical intensity of the lasing light is within the required range in the Step S5, the controller 50 corrects the current provided to the electrode 16 (Step S9) ………………. [0040] If it is determined that the optical intensity of the lasing light is within the required range in the Step S5, the controller 50 determines whether the heat value of the heater 14 is within a required range (Step S6) …………. [0041] If it is not determined that the heat value of the heater 14 is within the required range in the Step S6, the controller 50 corrects the electrical power to the heater 14 (Step S10) ………... the controller 50 corrects the electrical power by increasing and decreasing the current value provided to the heater 14. With the loop, the electrical power provided to the heater 14 is feedback controlled so that the electrical power provided to the heater 14 is controlled to be within the required range. If it is determined that the electrical power provided to the heater 14 is within the required range in the Step S6, the controller 50 executes the Step S4 again….” [Machida, ¶ [0034] - ¶ [0036], ¶ [0038] - ¶ [0041]].
Machida further teaches supplying a current to the heater and determining whether the heat value of the heater is within a required range (iteratively correcting when not within range), “[0055] If it is determined that the optical intensity of the lasing light is within the required range in the Step S17, the controller 50 determines whether the heat value of the heater 14 is within a required range (Step S18), similarly to the Step S13. If it is not determined whether the heat value of the heater 14 is within the required range in the Step S18, the controller 50 corrects the electrical power to the heater 14 (Step S23). After that, the controller 50 executes the Step S18 again. If it is determined whether the electrical power provided to the heat value of the heater 14 is within the required range in the Step S10, the controller 50 executes the Step S16 again. [0056] With the flowchart of FIG. 5, the heat value of the heater 14 is corrected accurately before the wavelength is controlled with the wavelength detector 30. In this case, the heat value of the heater 14 is substantially the same as a case where the heater is little degraded, even if the heater 14 is degraded. Therefore, the optical property of the SG-DBR region 11 is Substantially the same as a case where the heater 14 is little degraded. This results in a desirable wavelength according to the initial setting value.” [Machida, ¶ [0055] - ¶ [0056]].
However, Machida does not expressly teach a transition profile that explicitly accounts for different directional transitions (increase vs. decrease) when converging to target heater power. However, in an analogous art, Uesaka teaches supplying a pre-emphasis power for a preset period followed by a second (target) power, where the pre-emphasis power is greater when increasing and smaller when decreasing, “One aspect of the present application relates to a laser apparatus that comprises a wavelength tunable laser diode (t-LD) and a controller. The t-LD includes a heater to tune the emission wavelength thereof by being supplied with power. The controller controls the power supplied to the heater to re-tune the emission wavelength by varying the power from the first power Pa to the second power Pb. A feature of the laser apparatus of the present application is that, when the controller Supplies the pre-emphasis power Pp before supplying the second power Pb. The pre-emphasis power Pp is set to be greater than the second power Pb when the second power Pb is greater than the first power Pa, but less than the second power Pb when the second power Pb is less than the first power Pa………… by being triggered by a command to re-tune the emission wavelength, and (b) Supplying second power Pb to the heater after the preset period passes. A feature of the method is that the pre-emphasis power Pp is greater than the second power Pb when the second power Pb is greater than the first power Pa, but smaller than the second power Pb when the second power Pb is smaller than the first power Pa.” [Uesaka, col. 1-2].
Uesaka further teaches selecting transition parameters (e.g., coefficient and pre-emphasis period) by calculation or by referring to a look-up-table, and then supplying the pre-emphasis power for period AT and then supplying the target power, “……. However, the time until the stable emission wavelength becomes substantially independent of the power difference, APd-APs, and equal to the period AT of the pre-emphasis. FIGS. 10A and 10B are the histograms of the time until the stable emission wavelength. Without the pre-emphasis, which corresponds to FIG. 10A, the time scattered from 10 to 1300 microseconds (LL sec) whose standard deviation was 240 u sec. On the other hand, setting the pre-emphasis, the time converges within a range of 460 to 650 usec with the standard deviation of 27 u sec. The experiment shown in FIGS. 9 and 10 set the conditions of the pre-emphasis, namely, the period AT and the co-efficient K, were experimentally determined to be 450 u sec and 1.75, respectively.………… the embodiment of the present invention supplies the power Pp to the heater for a preset period before the target power Pb corresponding to the target wavelength is supplied. When the target power Pb is greater than the current power Pa, namely Pa-Pb, the temporal pre-emphasis power Pp is greater than the target power, namely, Pp-Pb. On the other hand, when the target power Pb is smaller than the current power Pa, PadPb, the temporal pre-emphasis power Pp is set to be smaller than the target power, Pp-Pb. The algorithm to provide the pre-emphasis power Pp to the heater in advance to the target power Pb may shorten the time to set the emission wavelength within the target plateau, and to set the emission wavelength in stable in the target wavelength.” [Uesaka, cols. 9-10].
A person of ordinary skill in the art (POSITA) would have been motivated to modify the wavelength-variable laser apparatus of Yamazaki to incorporate Machida’s wavelength-dependent heater-power targeting and feedback correction because both references are directed to the same technical field and problem space: heater-tuned semiconductor/photonic laser wavelength control. Yamazaki provides a concrete tunable laser architecture (including an SOA and heater-based tuning sections) capable of outputting light at selectable wavelengths. However, Yamazaki is not focused on a detailed control routine that (i) determines a target heater-power value based on wavelength and (ii) iteratively converges heater power until the output wavelength falls within a required range. Machida is expressly directed to that control problem, including retrieving target values from stored wavelength selection information (e.g., look-up table) and correcting heater power based on detected oscillation wavelength.
A POSITA would naturally view Machida’s scheme as a known method of improving the controllability and repeatability of a heater-tuned laser platform like Yamazaki’s, with a reasonable expectation of success, because both rely on the same predictable physical relationship: heater power affects temperature, which affects refractive index/optical path length and therefore wavelength.
A POSITA would further have been motivated to incorporate Uesaka’s transition/pre-emphasis tuning technique into the Yamazaki + Machida control system because Uesaka teaches a well-known and widely used approach for improving transient response in heater-based tuning: applying a defined power transition profile (e.g., pre-emphasis for a preset period followed by steady-state power) to reduce tuning time and improve stability. Heater-tuned systems exhibit thermal time constants; stepping directly to a final power can result in slow settling, overshoot, or prolonged convergence. Uesaka’s transition is a known solution to that recognized problem. Combining Machida’s LUT/feedback targeting with Uesaka’s transition shaping represents combining known elements according to known methods to yield predictable results namely faster acquisition of the desired wavelength and reduced time-to-stable wavelength without requiring undue experimentation. In KSR terms, this is the predictable use of prior-art control techniques applied to a known tunable laser platform to achieve expected performance improvements
Claim 2
with respect to claim 2, all the claim limitations of claim 1 are taught by Yamazaki, Machida, and Uesaka except wherein when the wavelength is a first wavelength, the control unit increases heater power from a first power value lower than a first target value to the first target value; and when the wavelength is a second wavelength, the control unit decreases heater power from a second power value higher than a second target value to the second target value. Yamazaki/Machida/Uesaka does not expressly teach when the wavelength is a first wavelength, the control unit increases heater power from a first power value lower than a first target value to the first target value; and when the wavelength is a second wavelength, the control unit decreases heater power from a second power value higher than a second target value to the second target value.
However, within analogous art, Uesaka teaches directional pre-emphasis behavior depending on whether the post-retune power increases or decreases (i.e., different power transition behavior for increase vs. decrease cases),” ………Supplying second power Pb to the heater after the preset period passes. A feature of the method is that the pre-emphasis power Pp is greater than the second power Pb when the second power Pb is greater than the first power Pa, but smaller than the second power Pb when the second power Pb is smaller than the first power Pa………...” [Uesaka, col. 2]
A person of ordinary skill in the art (POSITA) would have been motivated to implement direction-dependent convergence behavior (increase-to-target versus decrease-to-target) because heater-based tuning is known to behave differently depending on whether the heater is driven upward (heating) or downward (cooling). Thermal inertia, hysteresis, and non-linearities commonly produce different dynamic responses and settling characteristics for upward versus downward transitions. Uesaka expressly teaches selecting transition behavior based on whether the post-retune power increases or decreases, which directly addresses this practical control reality. Incorporating direction-dependent behavior into the Yamazaki + Machida controller would have been a routine optimization made in view of a finite number of identified, predictable solutions (i.e., choose different transition parameters for increasing vs decreasing cases), with a reasonable expectation of success because it is implemented in control logic rather than requiring new laser hardware.
Additionally, design incentives and market forces in optical communications (e.g., WDM channel switching and rapid wavelength acquisition) strongly motivate reducing retune time and increasing stability in both tuning directions. Implementing direction-dependent transitions is a low-cost firmware/software change that predictably reduces time to lock and improves stability. Thus, a POSITA would have been motivated to apply Uesaka’s direction-aware transition technique within Machida’s targeting and feedback scheme as an obvious improvement for robust bidirectional tuning.
Claim 3
with respect to claim 3, all the claim limitations of claim 1 are taught by Yamazaki, Machida, and Uesaka except wherein the control unit stores, in correspondence with each output wavelength, (i) the target value of the power supplied to the heater and (ii) the transition of the power until the target value is reached. Yamazaki/Machida/Uesaka does not expressly teach the control unit stores, in correspondence with each output wavelength, (i) the target value of the power supplied to the heater and (ii) the transition of the power until the target value is reached.However, within analogous art, Machida teaches obtaining a target value of electrical power to be supplied to the heater from stored wavelength selection information (e.g., a look-up table), corresponding to storing per-wavelength target values, “[0034] Then, the controller 50 determines whether the heat value of the heater 14 is within a required range according to an electrical power obtained with a voltage applied between both ends of the heater 14 and a current provided to the heater 14 (Step S3) ……………… [0035] If it is not determined that the heat value of the heater 14 is within the required range in the Step S3, the controller 50 corrects the temperature of the heater 14 (Step S7). The temperature of the heater 14 is corrected when the current provided to the heater 14 is changed and the electrical power obtained with the current provide do the heater 14 and the voltage applied between the both ends of the heater 14 is changed. After that, the controller 50 executes the Step S3 again. With the loop, the heat value of the heater 14 is feedback controlled so as to be within the required range. [0036] Next, the controller 50 determined whether the wavelength of the lasing light is within a required range according to the detection result of the wavelength detector 30 (Step S4) ………. [0038] If it is determined that the wavelength of the lasing light is within the required range in the Step S4, the controller 50 determines whether the optical intensity of the lasing light is within a required range (Step S5). In concrete, the controller 50 obtains the target value Im1 for feedback control from the look-up table 51, obtains the detection result Im1 of the light receiving element in the output detector 40, and deter mines whether the detection result Im1 is within a given range including the target value Im1 for feedback control. [0039]. If it is not determined that the optical intensity of the lasing light is within the required range in the Step S5, the controller 50 corrects the current provided to the electrode 16 (Step S9) ………………. [0040] If it is determined that the optical intensity of the lasing light is within the required range in the Step S5, the controller 50 determines whether the heat value of the heater 14 is within a required range (Step S6) …………. [0041] If it is not determined that the heat value of the heater 14 is within the required range in the Step S6, the controller 50 corrects the electrical power to the heater 14 (Step S10) ………... the controller 50 corrects the electrical power by increasing and decreasing the current value provided to the heater 14. With the loop, the electrical power provided to the heater 14 is feedback controlled so that the electrical power provided to the heater 14 is controlled to be within the required range. If it is determined that the electrical power provided to the heater 14 is within the required range in the Step S6, the controller 50 executes the Step S4 again….” [Machida, ¶ [0034] - ¶ [0036], ¶ [0038] - ¶ [0041]].
However, within analogous art, Uesaka teaches selecting transition parameters (e.g., coefficient K and pre-emphasis period AT) by calculation or by referring to a look-up table and then driving by pre-emphasis power for period AT and then by target power, corresponding to storing transition information per wavelength/retune, “……. However, the time until the stable emission wavelength becomes substantially independent of the power difference, APd-APs, and equal to the period AT of the pre-emphasis. FIGS. 10A and 10B are the histograms of the time until the stable emission wavelength. Without the pre-emphasis, which corresponds to FIG. 10A, the time scattered from 10 to 1300 microseconds (LL sec) whose standard deviation was 240 u sec. On the other hand, setting the pre-emphasis, the time converges within a range of 460 to 650 usec with the standard deviation of 27 u sec. The experiment shown in FIGS. 9 and 10 set the conditions of the pre-emphasis, namely, the period AT and the co-efficient K, were experimentally determined to be 450 u sec and 1.75, respectively.………… the embodiment of the present invention supplies the power Pp to the heater for a preset period before the target power Pb corresponding to the target wavelength is supplied. When the target power Pb is greater than the current power Pa, namely Pa-Pb, the temporal pre-emphasis power Pp is greater than the target power, namely, Pp-Pb. On the other hand, when the target power Pb is smaller than the current power Pa, PadPb, the temporal pre-emphasis power Pp is set to be smaller than the target power, Pp-Pb. The algorithm to provide the pre-emphasis power Pp to the heater in advance to the target power Pb may shorten the time to set the emission wavelength within the target plateau, and to set the emission wavelength in stable in the target wavelength.” [Uesaka, cols. 9-10].
A person of ordinary skill in the art (POSITA) would have been motivated to store, for each wavelength, the target heater-power value and the corresponding transition information because tunable laser systems are routinely calibrated across discrete wavelength/channel grids and then operated using stored calibration mappings. Machida already teaches obtaining target values from stored wavelength selection information such as a LUT, reflecting a conventional approach to reduce computational complexity and ensure repeatability during runtime. Storing per-wavelength target values enables fast channel selection, reduces convergence time, and ensures consistent behavior across devices and operating conditions.
A POSITA would also store transition information (or parameters defining the transition waveform) because transient behavior can vary by wavelength, device state, and ambient temperature. Uesaka teaches selecting transition parameters (including by look-up table) and then applying pre-emphasis for a defined period before applying the steady-state power. Combining Machida’s stored target-value selection with Uesaka’s stored transition-parameter selection is a predictable controller architecture: for a selected wavelength, retrieve (i) the final target power and (ii) the appropriate transition profile to reach it quickly. This is a conventional control design choice with a reasonable expectation of success.
Claim 8
Claim 8 recites a wavelength control method comprising causing a wavelength tunable laser apparatus (including an SOA and a heater) to perform processes of determining a wavelength-dependent target heater-power value and a transition until the target value is reached, and supplying power to the heater based on the determined transition.
Yamazaki teaches causing a wavelength variable laser device to output light via a semiconductor optical amplifier (SOA) in a wavelength-variable laser structure, “……... [0017] The wavelength variable laser device according to the present invention is characterized to include: an optical filter formed in a planar Lightwave circuit; a semiconductor optical amplifier that Supplies light to the optical filter; a light optical filter to the semiconductor optical amplifier via the optical filter, optical waveguides which are formed in the planar Lightwave circuit and connect the semiconductor optical amplifier, the optical filter, and the light reflecting section; a wavelength variable section that changes a wavelength of the light transmitting through the optical filter, and a phase variable section that changes a phase of the light propagated on the optical waveguides…...” [Yamazaki, ¶ [0017]].
Yamazaki further teaches that heaters control the wavelength by heating optical waveguides/resonators (wavelength-variable sections/phase-variable sections), “……… [0023] The optical filter 12 is a multiple optical resonator that is formed by coupling three ring resonators 24, 25, and 26 having different optical path lengths from each other. The ring resonators 24, 25, and 26 are structured with optical waveguides formed on the PLC 11. The wavelength variable sections 17, 18, and 19 are film-like heaters which change the temperatures of the optical waveguides constituting the ring resonators 24, 25, and 26, respectively. The phase variable section 20 is a film-like heater which changes the temperature of the optical waveguide 16 that connects the optical filter 12 and the light reflecting section 14. [0024] The optical waveguide 16 is formed on the PLC 11 simultaneously with the ring resonators 24, 25, 26 and optical waveguides 15, 27, 28. The phase variable section 20 is also formed on the PLC 11 simultaneously with the wavelength variable sections 17, 18, and 19. With the wavelength variable laser device 10, phase controls of the light transmitting through the optical filter 12 is done not by the SOA 13 but by the phase variable section 20 that is provided additionally. However, as described above, the phase variable section 20 is formed simultaneously with other structural elements of the PLC 11, so that there is no increase in the number of manufacturing steps even when the phase variable section 20 is provided additionally…….” [Yamazaki, ¶ [0023] - ¶ [0024]].
However, Yamazaki does not expressly teach determining, based on the wavelength of the output light, a target value of heater power and transition of the heater power until the target value is reached. However, in an analogous art, Machida teaches controlling a tunable semiconductor laser by adjusting the heater heat value until it reaches a given value and correcting the oscillation wavelength based on detected wavelength information, “……... [0016] The present invention has been made in view of the above circumstances and provides a method of controlling a semiconductor laser that obtains a desired wavelength even if the heater is degraded. [0017] According to an aspect of the present invention, there is provided a method of controlling a semiconductor laser having a wavelength selection portion, a refractive index of the wavelength selection portion being controllable with a heater including: a starting sequence including a first step for adjusting a heat value of the heater until the heat value of the heater reaches a given value; and a wavelength control sequence including a second step for correcting a wavelength of the semiconductor laser according to a detection result of an oscillation wavelength of the semiconductor laser after the starting sequence. [0018] With the method, the heat value of the heater is accurately corrected before the wavelength control sequence. In this case, optical property of the wavelength selection portion is Substantially the same as a case where the heater is little degraded, even if the heater is degraded. Therefore, it is possible to obtain a desirable oscillation wavelength ………” [Machida, ¶ [0016] - ¶ [0018]].
Machida further teaches determining a wavelength/channel-dependent target value of electrical power to be supplied to heater 14 by obtaining the target value P for feedback control from a look-up table 51 (stored control information for each channel), and then determining whether the electrical power to the heater is within a range including the target value P (and correcting the electrical power when not within range), “The ROM of the controller 50 stores control information … The control information is … stored in a look-up table 51 … the look-up table 51 includes … a target value for feedback control in every channel … Then, the controller 50 determines whether the heat value of the heater 14 is within a required range … In concrete, the controller 50 obtains the target value P for feedback control from the look-up table 51 …” [Machida, ¶ [0030] - ¶ [0031], ¶ [0034]].
Machida further teaches supplying current/power to the heater and determining whether the heater heat value is within a required range (and correcting when not within range), which corresponds to transitioning heater power until the target is reached, “…………… [0055] If it is determined that the optical intensity of the lasing light is within the required range in the Step S17, the controller 50 determines whether the heat value of the heater 14 is within a required range (Step S18), similarly to the Step S13. If it is not determined whether the heat value of the heater 14 is within the required range in the Step S18, the controller 50 corrects the electrical power to the heater 14 (Step S23). After that, the controller 50 executes the Step S18 again. If it is determined whether the electrical power provided to the heat value of the heater 14 is within the required range in the Step S10, the controller 50 executes the Step S16 again. [0056] With the flowchart of FIG. 5, the heat value of the heater 14 is corrected accurately before the wavelength is controlled with the wavelength detector 30. In this case, the heat value of the heater 14 is substantially the same as a case where the heater is little degraded, even if the heater 14 is degraded. Therefore, the optical property of the SG-DBR region 11 is Substantially the same as a case where the heater 14 is little degraded. This results in a desirable wavelength according to the initial setting value……………” [Machida, ¶ [0055] - ¶ [0056]].
However, Machida does not expressly teach supplying heater power based on a defined transition profile (e.g., pre-emphasis for a preset period, then target power) as recited in claim 8. However, in an analogous art, Uesaka teaches supplying pre-emphasis power to the heaters before supplying the power corresponding to the re-tuned emission wavelength to accelerate stability (i.e., supplying power based on a determined transition), “A feature of the method is that the pre-emphasis power Pp is greater than the second power Pb when the second power Pb is greater than the first power Pa, but smaller than the second power Pb when the second power Pb is smaller than the first power Pa.” [Uesaka, col. 2]
Uesaka further teaches determining the transition parameters (e.g., coefficient K and pre-emphasis period AT) by calculation or by referring to a look-up-table, driving the heater by pre-emphasis power for period AT, and then driving by the target/base power, “……. However, the time until the stable emission wavelength becomes substantially independent of the power difference, APd-APs, and equal to the period AT of the pre-emphasis. FIGS. 10A and 10B are the histograms of the time until the stable emission wavelength. Without the pre-emphasis, which corresponds to FIG. 10A, the time scattered from 10 to 1300 microseconds (LL sec) whose standard deviation was 240 u sec. On the other hand, setting the pre-emphasis, the time converges within a range of 460 to 650 usec with the standard deviation of 27 u sec. The experiment shown in FIGS. 9 and 10 set the conditions of the pre-emphasis, namely, the period AT and the co efficient K, were experimentally determined to be 450 u sec and 1.75, respectively.………… the embodiment of the present invention supplies the power Pp to the heater for a preset period before the target power Pb corresponding to the target wavelength is supplied. When the target power Pb is greater than the current power Pa, namely Pa-Pb, the temporal pre-emphasis power Pp is greater than the target power, namely, Pp-Pb. On the other hand, when the target power Pb is smaller than the current power Pa, PadPb, the temporal pre-emphasis power Pp is set to be smaller than the target power, Pp-Pb. The algorithm to provide the pre-emphasis power Pp to the heater in advance to the target power Pb may shorten the time to set the emission wavelength within the target plateau, and to set the emission wavelength in stable in the target wavelength.” [Uesaka, cols. 9-10].
A person of ordinary skill in the art (POSITA) would have been motivated to implement the claimed wavelength control method because it represents the natural operational procedure for the obvious apparatus combination of claim 1. Once Yamazaki’s tunable laser hardware is combined with Machida’s wavelength-dependent target selection and
feedback correction and Uesaka’s transition shaping, operating the system necessarily involves: outputting light from the SOA; controlling wavelength by heater-based heating; determining a target heater power value based on wavelength; determining a transition profile until the target is reached; and supplying heater power according to that transition. Thus, claim 8’s method steps follow directly from using the combined apparatus elements according to their established functions.
Machida provides the articulated rationale for selecting target heater power based on stored wavelength selection information and iteratively correcting heater power based on detected wavelength until the wavelength is within a required range. Uesaka provides the articulated rationale for applying a transition profile (e.g., pre-emphasis for a preset period then steady-state power) to reduce time-to-stable wavelength. A POSITA would combine these teachings because they address complementary aspects of the same tuning problem accuracy and convergence (Machida) plus faster transient stabilization (Uesaka) and the combination yields predictable results with a reasonable expectation of success. Accordingly, the method of claim 8 would have been obvious as a routine application of known control techniques to a known tunable laser platform.
Claim 4 is rejected under 35 U.S.C. §103 as being unpatentable over Yamazaki et al. in view of Machida et al., Uesaka et al. and Chen et al. (US20090161113A1).
Claim 4
With respect to claim 4, all the claim limitations of claim 1 are taught by Yamazaki, Machida, and Uesaka except wherein the control unit supplies power corresponding to a circulation power at which phase is circulated, and then supplies power based on the transition until a target value is reached. However, within analogous art, Uesaka teaches supplying a transition profile (pre-emphasis then target power) until the target power is reached. Further, within analogous art, Chen teaches that the amount of heater power Pr required to introduce a 2π phase shift corresponds to moving/tuning the resonant frequency by one free spectral range (FSR), which corresponds to “circulation power”/“phase … circulated,”, “[0023] Generally, the phase shift in the ring resonator 110 is linearly proportional to the phase shifter's applied heater power. Therefore, the phase of the ring resonator can be expressed as: where P is the applied heater power, P, is the required power to shift the phase by 21, and p is the initial phase of the ring resonator. In general, cp=(P/P)2t, where P is the power required to position the ring's resonant wavelength at the laser tone frequency. As an example, if a ring resonator has an initial resonance condition at the laser tone wavelength (wo), [0024] This is illustrated in FIG. 2A, which is a plot of the laser intensity I, at the detector 150 versus the heater power applied to the phase shifter 112, with the coupler 102 fixed at a non-zero coupling setting. The tunable coupler 102 of the ring resonator 110 affects both the phase (p and the coupling coefficient K (also referred to as the coupling strength or coupling ratio) of the ring resonator 110. The dip 202 in the laser intensity corresponds to a first resonant condition, and the second dip 204 corresponds to a second resonant condition. The difference between power settings Po and Po (corresponding to resonant dips 202 and 204) is the amount of power, P., required to introduce a phase shift of 2C to the ring resonator, or to move or tune the resonant frequency by one free spectral range (FSR) of the ring resonator 110. [0025] Since the phase shift introduced by the phase shifter 112 is typically about proportional to the heater power, the phase of the ring resonator 110 can be calibrated as a function of the power applied to the heater by tuning the phase shifter 112 through a range corresponding to at least one FSR. Based on the approximate linear relationship between the phase and the applied heater power………...” [Chen, ¶ [0023] -¶ [0025]].
A person of ordinary skill in the art (POSITA) would have been motivated to incorporate Chen’s ‘2π/FSR periodicity’ teaching into the Yamazaki + Machida + Uesaka tuning framework because phase-based and resonator-based tuning is inherently periodic. In periodic tuning systems (e.g., ring resonators and phase shifters), the relationship between heater power and resonant condition can repeat with a period corresponding to a 2π phase shift and one free spectral range (FSR). In such systems, a common engineering approach is to perform a coarse ‘phase circulation’ (i.e., wrap across one or more periods) to reach the correct resonance order before applying fine stabilization at the final target wavelength. Chen provides an explicit calibration basis for identifying the heater-power period Pr for a 2π shift / one FSR movement. A POSITA would use that periodic calibration to implement a ‘circulation power’ step as an identified, predictable solution for coarse positioning in periodic tuning structures, with a reasonable expectation of success.
After coarse circulation/positioning, a POSITA would then apply Uesaka’s transition profile and Machida’s wavelength-dependent target selection and feedback correction to converge rapidly and accurately to the final target wavelength. The combination yields predictable results: (i) Chen improves coarse resonance order acquisition via a known periodic calibration; (ii) Uesaka reduces settling time via transition shaping; and (iii) Machida ensures accurate convergence to the target via LUT/feedback correction. The integrated approach is motivated by the recognized need in tunable sources to combine coarse acquisition with fast, stable fine tuning.
Claim 5 is rejected under 35 U.S.C. §103 as being unpatentable over Yamazaki et al. in view of Machida et al., Uesaka et al., Chen et al., and Gao et al. (US20200280173A1).
Claim 5
With respect to claim 5, all the claim limitations of claim 1 are taught by Yamazaki, Machida, and Uesaka except wherein the heater changes the refractive index by heating a silicon optical waveguide. Yamazaki, Machida, and Uesaka do not expressly teach a silicon optical waveguide whose refractive index is changed via heater-based heating. However, within analogous art, Gao teaches silicon photonic frequency selective elements on a silicon integrated circuit that are tuned through an integrated micrometer-size heater using the thermo-optic effect, i.e., heating the silicon waveguide structure to change its refractive index and thus shift the filtering/resonant frequency, “One of the fundamental features for tunable lasers in coherent communication systems is the highly accurate frequency control and long-term frequency stability. The filtering frequencies of the frequency selective elements can be tuned through the integrated micrometer-size heater next to them using the thermo-optic effect. However, due to the high thermal conductivity of the silicon material, the frequencies of the frequency selective elements on the silicon integrated circuits can be easily interfered by chip thermal disturbances …” [Gao, ¶ [0044]].
A person of ordinary skill in the art (POSITA) would have been motivated to implement heater-controlled tuning using a silicon optical waveguide, as taught by Gao, because silicon photonics provides a predictable thermo-optic tuning mechanism and strong integration benefits. Gao teaches that heater current raises temperature and changes refractive index through the thermo-optic effect in silicon, shifting resonance/frequency and enabling wavelength control. This is a well-established technique; implementing the tuning structure in silicon yields predictable results (heater power → temperature change → refractive index change → wavelength/resonance shift) and offers practical advantages such as compactness, integrability, and manufacturability.
Further, Machida’s and Uesaka’s control techniques (target value determination, feedback convergence, and transition shaping) are not tied to any single material platform; they apply generally to heater-tuned systems where heater power maps to wavelength. Thus, integrating Gao’s silicon waveguide heater tuning with the combined Yamazaki/Machida/Uesaka control logic is the predictable use of prior-art elements according to their established functions, with a reasonable expectation of success.
Claims 6-7 are rejected under 35 U.S.C. §103 as being unpatentable over Chou et al. (US20120314989A1) in view of Lam et al. (US20110293279A1), Yamazaki et al., Machida et al., and Uesaka et al.
Claim 6
Chou is directed to an optical transceiver module and teaches an optical receiver module and transmission control that converts between optical and electrical signals. In particular, Chou teaches an optical transceiver including a circuit board, one or more optical sub-assemblies, and an interface, where the optical sub-assembly includes an optoelectronic component and an integrally-formed optical fiber; the optoelectronic component receives an optical signal from the integrally-formed optical fiber and converts the optical signal to an electrical signal and transmits the electrical signal to the circuit board, and is also configured to receive an electrical signal from the circuit board and converts the electrical signal to an optical signal and transmits the optical signal to the integrally-formed optical fiber, “[0017] Referring to FIG. 1 and FIG. 2, one preferred embodiment of current disclosure. An optical transceiver 10 includes a circuit board 101, at least two optical sub-assemblies 109, and an interface 107. [0018] The optical sub-assembly 109 electrically connects with the circuit board 101 and includes an optoelectronic component 103 and an integrally-formed optical fiber 105. The optoelectronic component 103 receives an optical signal from the integrally-formed optical fiber 105 and converts the optical signal to an electrical signal. Moreover, the optoelectronic component 103 further transmits the electrical signal to the circuit board 101. The optoelectronic component 103 can be also configured to receive an electrical signal from the circuit board 101 and converts the electrical signal to an optical signal, thereafter the optoelectronic component 103 further transmits the optical signal to the integrally-formed optical fiber 105.” [Chou, FIG. 1 and FIG. 2 ¶ [0017] -¶ [0018]].
Chou further teaches an electrical interface and an optical cable interface for transmitting/receiving signals. Specifically, Chou teaches that the interface includes a plurality of pins penetrating through the circuit board and can electrically connect the optical transceiver to another device/apparatus; and that an optical fiber connector connects one end of the integrally-formed optical fiber and can connect the optical transceiver to an external optical fiber/device, “…….[0019] The interface 107 includes a plurality of pins 1071 which are penetrating through the circuit board 101, with which the interface 107 electrically connects. Optionally, the optical transceiver 10 electrically connects to the other device or apparatus (not shown) via the interface 107. [0023] The optical fiber connector 201 connects one end of the integrally-formed optical fiber 105. Optionally, the optical transceiver 11 connects to the other device, apparatus or an optical fiber (not shown) via the optical fiber connector 201. The protection device 203 is disposed on the junction position which is between the integrally-formed optical fiber 105 and the optoelectronic component 103. The protection device 203 encloses the junction position in order to protect the connection between the integrally-formed optical fiber 105 and the optoelectronic component 103 from breaking………” [Chou, ¶ [0019] & ¶ [0023]].
However, within analogous art, Lam is directed to optical WDM transceivers and explicitly teaches that optical WDM transceivers transmit and receive data by combining a number of different optical channels or signals at different WDM wavelengths onto a single fiber, “……... [0002] Various optical fiber transmission systems use optical WDM transceivers to transmit and receive data by combining a number of different optical channels or signals at different WDM wavelengths onto a single fiber. Light at these WDM wavelengths is modulated as optical signals at different WDM wavelengths to carry data of different signals, respectively. For example, an optical fiber transmission system can be designed to include n number of optical WDM channels each with a data rate of m Gibfs to transmit through a single fiber with data throughput rate at nxim Gibfs. As such, data transmission at a data throughput rate of 100 Gb/s can be achieved by using, for example, 10 optical WDM channels each at a channel data rate of 10 Gb/s or 4 optical WDM channels each at a channel data rate of 25 Gbfs. To achieve a Sufficiently high data throughput rate at nxim Gibfs, the number of optical WDM channels, n, can be increased to reduce the data rate m per optical channel to advantageously use relatively matured low-data-rate optical WDM technologies and the associated CMOS electronic technologies for the electronic driver and data processing circuits……….” [Lam, ¶ [0002]].
Lam further teaches that each optical WDM transceiver includes a transmitter part that transmits one or more optical WDM signals and a receiver part that receives one or more optical WDM signals, “[0003] Optical WDM transceivers can be in various con figurations where each transceiver includes a transmitter part that transmits one or more optical WDM signals and a receiver part that receives one or more optical WDM signals. An integrated multi-wavelength WDM transceiver is a transceiver in a compact platform that allows multiple streams of data to be simultaneously placed on a single physical input and output (I/O) port using multiple optical WDM wave lengths from an array of lasers operated at the optical WDM wavelengths. Such integration offers a number of advantages including low power operation, spatial and cost efficiency, improved system reliability, and operational simplicity. In various optical WDM systems, integrated Coarse WDM (CWDM) or Dense WDM (DWDM) compact form pluggable (CFP) transceivers can be used to offer an economical and power-efficient way to implement 100-Gb/s transmission on a single fiber by an array of CWDM or DWDM lasers, each transmitting at 10 Gb/s or 25 Gb/s aligning with CMOS electronic drive speeds………...” [Lam, ¶ [0003]].
Accordingly, Lam provides explicit motivation and context for implementing a tunable laser-based transmitter in a transceiver module (e.g., to select/operate at WDM wavelengths), which would have motivated a POSITA to implement the wavelength tunable laser apparatus of Yamazaki (as controlled by Machida and Uesaka) within the transceiver platform of Chou to enable WDM wavelength selection and predictable transceiver operation.
However, Chou does not expressly teach that the transceiver includes a wavelength tunable laser apparatus having (i) a semiconductor optical amplifier, (ii) a heater for wavelength control based on supplied power, and (iii) a control unit that determines a target value of heater power and transitions heater power until the target value is reached. However, as discussed above, Yamazaki teaches a wavelength variable laser device including a semiconductor optical amplifier and heater-based wavelength-variable sections, “……… [0023] The optical filter 12 is a multiple optical resonator that is formed by coupling three ring resonators 24, 25, and 26 having different optical path lengths from each other. The ring resonators 24, 25, and 26 are structured with optical waveguides formed on the PLC 11. The wavelength variable sections 17, 18, and 19 are film-like heaters which change the temperatures of the optical waveguides constituting the ring resonators 24, 25, and 26, respectively. The phase variable section 20 is a film-like heater which changes the temperature of the optical waveguide 16 that connects the optical filter 12 and the light reflecting section 14. [0024] The optical waveguide 16 is formed on the PLC 11 simultaneously with the ring resonators 24, 25, 26 and optical waveguides 15, 27, 28. The phase variable section 20 is also formed on the PLC 11 simultaneously with the wavelength variable sections 17, 18, and 19. With the wavelength variable laser device 10, phase controls of the light transmitting through the optical filter 12 is done not by the SOA 13 but by the phase variable section 20 that is provided additionally. However, as described above, the phase variable section 20 is formed simultaneously with other structural elements of the PLC 11, so that there is no increase in the number of manufacturing steps even when the phase variable section 20 is provided additionally…….” [Yamazaki, ¶ [0023] - ¶ [0024]].
Yamazaki does not expressly teach determining a wavelength-dependent target value of electrical power to be supplied to a heater (e.g., for a selected wavelength/channel) and iteratively correcting heater power until the target value is reached. However, within analogous art, Machida teaches obtaining a target value P for feedback control from a look-up table 51 (stored control information for each channel), determining whether electrical power to heater 14 is within a range including the target value P, and correcting electrical power by increasing/decreasing heater current in a feedback loop until within the required range, “Then, the controller 50 determines whether the heat value of the heater 14 is within a required range according to an electrical power … In concrete, the controller 50 obtains the target value P for feedback control from the look-up table 51 … If it is not determined … the controller 50 corrects … the electrical power … is changed … With the loop … feedback controlled … If it is not determined … the controller 50 corrects the electrical power to the heater 14 … increasing and decreasing the current value provided to the heater 14 … feedback controlled …” [Machida, ¶ [0034] - ¶ [0035], ¶ [0041]].
Within analogous art, Uesaka teaches supplying heater power according to a defined transition profile (pre-emphasis power Pp for a preset period followed by the target/second power Pb) to accelerate stabilization after a re-tune event, where the pre-emphasis direction depends on whether the heater power is increasing or decreasing, “The pre-emphasis power Pp is set to be greater than the second power Pb when the second power Pb is greater than the first power Pa, but less than the second power Pb when the second power Pb is less than the first power Pa …” [Uesaka, col. 1-2].
A person of ordinary skill in the art (POSITA) would have been motivated to combine Chou’s optical transceiver module architecture with Lam’s WDM transceiver context and Yamazaki’s wavelength tunable laser apparatus because the references address complementary aspects of the same system-level design: a transceiver with wavelength-selectable transmission. Chou provides a practical transceiver platform (including an optical receiver module for optical-to-electrical conversion, an optical cable interface for fiber coupling, and an electrical interface/control circuitry). Lam explicitly teaches WDM transceivers that transmit and receive multiple channels at different wavelengths over a single fiber and that include transmitter and receiver parts thereby providing an articulated design incentive and market-driven motivation to implement wavelength selectable/tunable transmitters within transceiver modules. In WDM deployments, tunable transceivers reduce inventory (one module can support multiple wavelengths), improve provisioning flexibility, and enable faster recovery/maintenance by tuning spare modules to required channels. Accordingly, a POSITA would have been motivated to employ Yamazaki’s tunable laser as the transmitter source within Chou’s transceiver environment to enable WDM wavelength selection, as suggested by Lam. A POSITA would further apply Machida’s LUT/feedback heater-power targeting to ensure accurate placement at the desired WDM wavelength/channel, and incorporate Uesaka’s transition/pre-emphasis waveform to reduce time-to-stable wavelength during start-up and channel switching. This is a predictable integration of known elements according to known methods to yield predictable results (selectable wavelength output + faster stabilization + accurate channel lock), with a reasonable expectation of success because it requires primarily integration and control logic selection rather than reinvention of the transceiver architecture.
Thus, the combination is supported by an articulated reasoning with rational underpinning: Chou supplies the transceiver architecture; Lam supplies explicit WDM motivation for wavelength-selectable transmitter operation; Yamazaki supplies the tunable laser hardware; Machida supplies wavelength-dependent target-value and feedback convergence; and Uesaka supplies transition shaping to reduce tuning time. The resulting transceiver functionality is predictable and would have been obvious to a POSITA.
Claim 7
With respect to claim 7, all the claim limitations of claim 6 are taught by Chou in view of Lam, Yamazaki, Machida, and Uesaka except wherein the control unit increases heater power from a lower-than-target value toward a target value when the wavelength is a first wavelength and decreases heater power from a higher-than-target value toward a target value when the wavelength is a second wavelength. Chou, Lam, Yamazaki and Machida do not expressly teach the control unit increases heater power from a lower-than-target value toward a target value when the wavelength is a first wavelength and decreases heater power from a higher-than-target value toward a target value when the wavelength is a second wavelength.
However, within analogous art, Uesaka teaches directional pre-emphasis behavior depending on whether the post-retune power increases or decreases (i.e., different transition behavior for increase vs. decrease), “One aspect of the present application relates to a laser apparatus that comprises a wavelength tunable laser diode (t-LD) and a controller. The t-LD includes a heater to tune the emission wavelength thereof by being supplied with power. The controller controls the power supplied to the heater to re-tune the emission wavelength by varying the power from the first power Pa to the second power Pb. A feature of the laser apparatus of the present application is that, when the controller Supplies the pre-emphasis power Pp before supplying the second power Pb. The pre-emphasis power Pp is set to be greater than the second power Pb when the second power Pb is greater than the first power Pa, but less than the second power Pb when the second power Pb is less than the first power Pa………… by being triggered by a command to re-tune the emission wavelength, and (b) Supplying second power Pb to the heater after the preset period passes. A feature of the method is that the pre-emphasis power Pp is greater than the second power Pb when the second power Pb is greater than the first power Pa, but smaller than the second power Pb when the second power Pb is smaller than the first power Pa.” [Uesaka, col. 1-2].
A person of ordinary skill in the art (POSITA) would have been motivated to incorporate Uesaka’s direction-aware transition strategy into the tunable laser controller within the transceiver environment of claim 6 because WDM transceivers routinely retune across a wavelength grid in both directions. Depending on the target channel, the required heater power may increase or decrease. Uesaka teaches selecting different transition behavior based on whether post-retune power increases or decreases. This provides a finite, predictable set of options for improving tuning response: use different transition parameters for up-tuning versus down-tuning. Implementing that logic is a routine firmware/control enhancement with a reasonable expectation of success, because it leverages known heater-drive techniques and does not require changing optical hardware.
Moreover, transceiver operational requirements (fast reconfiguration, reduced downtime, stable channel lock) provide strong design incentives to reduce tuning time and improve stability in both directions. Applying Uesaka’s direction-aware transition within the Chou/Lam/Yamazaki/Machida framework yields predictable results of faster channel switching and more reliable stabilization, and therefore would have been obvious to a POSITA.
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