The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
DETAILED ACTION
Claim Interpretation
Claims 1, 10, and 11 each recite both a “rib waveguide’ and its “slab regions” and contradict the standard terminology according to which a rib waveguide has a rectangular cross-section without slab regions. Only a ridge waveguide has slab (thinner) regions flanking a (thicker) central portion. While the limitation “rib waveguide” is interpreted according to the disclosure to actually mean a ridge waveguide (as shown in Fig. 2 of the instant application), Applicant is advised to consider correcting the above-noted discrepancy.
Claim Objections
Claims 1 – 9 are objected to because of the following informalities:
Claim 1 recites the limitation “the signal light” twice in which the article “the” causes insufficient antecedent basis issues. For the purposes of this Action, each instance of the limitation is interpreted as “a signal light”.
Claim 1 recites the limitation “at least part” which appears to have a typesetting issue/omission. For the purposes of this Action, the limitation is interpreted as “at least a part”.
Appropriate corrections are required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all 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 of this title, 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.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 8, 10, and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Lundqvist (US 6,332,048 B1) in view of Yegnanarayanan et al (US 2003/0142943 A1).
Regarding claim 1, Lundquist discloses (Figs. 1 – 4; Abstract; 3:46 – 5:18 and 6:52 – 7:48) an optical device (electro-absorption modulator (EAM); Abstract), comprising:
a rib/ridge optical waveguide formed on a substrate (as shown by a waveguide cross-section in Fig. 4C; “The electro-absorption modulator is preferably arranged to be used for intensity modulation of digital signals for fiber optic transmission. It may be monolithically integrated with a DFB laser (Distributed Feedback Laser) on a semiconductor substrate” at 2:47 - 51);
a P doped region 43 and an N doped region 42 formed within the rib optical waveguide to sandwich its core layer 41 (as shown in Figs. 4B and 4C; “the reference numeral 41 denotes waveguide core, 42 denotes n-doped InP, 43 denotes p-doped InP, 44 denotes semi-isolating InP, 45 denotes electrode, and 46 denotes mask” at 7:34 – 38);
an electrode 45/55 connected to the P doped region 43/53 (as seen in Figs. 4B, 4D, and 5E); and
an optical absorption structure (EAM) that is configured to implement optical absorption of signal light passing through the rib optical waveguide according to an electric current that flows through the electrode (Fig. 2; 5:23 – 6:6:52); and make (by tapering the rib waveguide width, as shown in Fig. 4A), in the optical absorption, a signal light passing through an optical input portion (the left portion of the rib waveguide in Fig. 4A) of the rib optical waveguide lower in optical attenuation rate than a signal light passing through at least a part of the rib optical waveguide (on the right side of the rib waveguide in Fig. 4A), the part excluding the optical input (left) portion: indeed, Fig. 3 shows that the optical attenuation rate (Absorption rate / unit length) of a tapered rib waveguide is lower within the optical input portion (e.g., within 0 – 10 microns from the input end) than that within a part of the rib optical waveguide (e.g., within 30 – 50 microns) excluding the optical input (left) portion.
While Lundquist illustrates an EAM embodiment with a vertical arrangement of doped regions and electrodes, horizontal arrangements/designs are also well known in the art. For example, Yegnanarayanan discloses (Fig. 1; Abstract; para. 0024 – 0040) an optical device that can be configured as an EAM (para. 0034), which is the same device type as that in Lundquist and comprises a horizontal arrangement of doped regions and electrodes. Specifically, the device/EAM comprises:
a rib/ridge optical waveguide 108 formed on a substrate 104 (“A waveguide 108 is formed in the intrinsic Si layer 106” at para. 0026);
a P doped region 110 formed in one of slab (thinner) regions of the rib optical waveguide 108;
an N doped region 112 formed in the other one of the slab (thinner) regions of the rib optical waveguide 108;
a first electrode 114 connected to the P doped region 110;
a second electrode 116 connected to the N doped region 112 (“The optical device 100 includes a region 110 doped with P-type material and a region 112 doped with N-type material, which forms a semiconductor diode. The P-doped region 110 may be in contact with an anode 114 and the N-doped region 112 may be in contact with a cathode 116” at para. 0026).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the EAM device of Lundquist can be modified to have a horizontal arrangement of doped regions and electrodes, as a suitable/workable design that is well known in the art and explicitly illustrated by Yegnanarayanan.
In light of the foregoing analysis, the Lundquist – Yegnanarayanan combination teaches expressly or renders obvious all of the recited limitations.
Regarding claim 10, the teachings of Lundquist and Yegnanarayanan combine (see the arguments and motivation for combining, as provided above for claim 1) to teach expressly or render obvious all of the recited limitations. Specifically, the Lundquist – Yegnanarayanan combination considers an optical transmitting device, comprising:
a light source (“The electro-absorption modulator is preferably arranged to be used for intensity modulation of digital signals for fiber optic transmission. It may be monolithically integrated with a DFB laser (Distributed Feedback Laser) on a semiconductor substrate” at 2:47 – 50 of Linquist);
an optical modulator (of electro-absorption type, as taught by Lindquist) that optically modulates light from the light source by using a transmitted signal and transmits transmitted light (ibid); and
an optical device that attenuates the light in the optical modulator, wherein the optical device includes (a horizontal arrangement of doped regions and electrodes, as shown in Fig. 1 by Yegnanarayanan):
a rib/ridge optical waveguide 108 formed on a substrate 104 (“A waveguide 108 is formed in the intrinsic Si layer 106” at para. 0026 of Yegnanarayanan);
a P doped region 110 formed in one of slab (thinner) regions of the rib optical waveguide 108;
an N doped region 112 formed in the other one of the slab (thinner) regions of the rib optical waveguide 108;
a first electrode 114 connected to the P doped region 110;
a second electrode 116 connected to the N doped region 112 (“The optical device 100 includes a region 110 doped with P-type material and a region 112 doped with N-type material, which forms a semiconductor diode. The P-doped region 110 may be in contact with an anode 114 and the N-doped region 112 may be in contact with a cathode 116” at para. 0026); and
an optical absorption structure (EAM) that is configured, according to Lindquist, to implement optical absorption of signal light passing through the rib optical waveguide according to an electric current that flows through the electrode (Fig. 2; 5:23 – 6:6:52 of Lindquist); and make (by tapering the rib waveguide width, as shown in Fig. 4A), in the optical absorption, a signal light passing through an optical input portion (the left portion of the rib waveguide in Fig. 4A) of the rib optical waveguide lower in optical attenuation rate than a signal light passing through at least a part of the rib optical waveguide (on the right side of the rib waveguide in Fig. 4A), the part excluding the optical input (left) portion: indeed, Fig. 3 shows that the optical attenuation rate (Absorption rate / unit length) of a tapered rib waveguide is lower within the optical input portion (e.g., within 0 – 10 microns from the input end) than that within a part of the rib optical waveguide (e.g., within 30 – 50 microns) excluding the optical input (left) portion.
Regarding claim 11, the teachings of Lundquist and Yegnanarayanan combine (see the arguments and motivation for combining, as provided above for claim 1) to teach expressly or render obvious all of the recited limitations. Specifically, the Lundquist – Yegnanarayanan combination considers an optical receiving device, comprising:
a light source (“The electro-absorption modulator is preferably arranged to be used for intensity modulation of digital signals for fiber optic transmission. It may be monolithically integrated with a DFB laser (Distributed Feedback Laser) on a semiconductor substrate” at 2:47 – 50 of Linquist);
an optical receiver that receives a received signal from received light using light from the light source (“the monolithic optical device may be implemented as a standalone optical component or as a sub-component within an optical subsystem comprising additional components such as optical taps, detectors, and feedback control circuits. This embodiment may be used to perform dynamic spectral equalization, for example” at para. 0039 of Yegnanarayanan, emphasis added); and
an optical device (variable optical attenuator (VOA); “the optical device 100 may be a fast variable optical attenuator, which attenuates an optical signal passing through it. FIG. 2 shows an example system 200 according to an embodiment of the present invention in which finer control of EDFA spectral gain equalization may be achieved using the optical device 100 as a variable optical attenuator, which equalizes optical energy distribution across multiple channels” at para. 0034 of Yegnanarayanan, emphasis added) that attenuates the light in the optical receiver,
wherein the optical device includes (a horizontal arrangement of doped regions and electrodes, as shown in Fig. 1 by Yegnanarayanan):
a rib/ridge optical waveguide 108 formed on a substrate 104 (“A waveguide 108 is formed in the intrinsic Si layer 106” at para. 0026 of Yegnanarayanan);
a P doped region 110 formed in one of slab (thinner) regions of the rib optical waveguide 108;
an N doped region 112 formed in the other one of the slab (thinner) regions of the rib optical waveguide 108;
a first electrode 114 connected to the P doped region 110;
a second electrode 116 connected to the N doped region 112 (“The optical device 100 includes a region 110 doped with P-type material and a region 112 doped with N-type material, which forms a semiconductor diode. The P-doped region 110 may be in contact with an anode 114 and the N-doped region 112 may be in contact with a cathode 116” at para. 0026); and
an optical absorption structure (EAM) that is configured, according to Lindquist, to implement optical absorption of signal light passing through the rib optical waveguide according to an electric current that flows through the electrode (Fig. 2; 5:23 – 6:6:52 of Lindquist); and make (by tapering the rib waveguide width, as shown in Fig. 4A), in the optical absorption, a signal light passing through an optical input portion (the left portion of the rib waveguide in Fig. 4A) of the rib optical waveguide lower in optical attenuation rate than a signal light passing through at least a part of the rib optical waveguide (on the right side of the rib waveguide in Fig. 4A), the part excluding the optical input (left) portion: indeed, Fig. 3 shows that the optical attenuation rate (Absorption rate / unit length) of a tapered rib waveguide is lower within the optical input portion (e.g., within 0 – 10 microns from the input end) than that within a part of the rib optical waveguide (e.g., within 30 – 50 microns) excluding the optical input (left) portion.
Regarding claim 8, the teachings of Lundquist and Yegnanarayanan combine (see the arguments and motivation for combining, as provided above for claim 1) to teach expressly or render obvious all of the recited limitations. Specifically, the Lundquist – Yegnanarayanan combination considers that the optical absorption structure has an optical waveguide in the rib/ridge optical waveguide, the optical waveguide gradually decreasing in waveguide width from an optical output portion (the right end in Fig. 4A of Lindquist) to the optical input portion (the left end in Fig. 4A) of the rib optical waveguide, wherein the optical absorption structure has a structure that makes confinement of the signal light passing through the optical input portion larger than confinement of the signal light passing through the optical output portion and thereby makes the signal light passing through the optical input portion lower in optical attenuation rate than the signal light passing through at least the part of the rib optical waveguide, the part excluding the optical input portion: indeed, Fig. 3 shows that the optical attenuation rate (Absorption rate / unit length) of a tapered rib waveguide is lower within the optical input portion (e.g., within 0 – 10 microns from the input end) than that within a part of the rib optical waveguide (e.g., within 30 – 50 microns) excluding the optical input (left) portion.
Claims 2 and 9 are rejected under 35 U.S.C. 103 as being unpatentable over Lundqvist in view of Yegnanarayanan, and further in view of Wipiejewski et al (US 2004/0109658 A1).
Regarding claim 2, Lundquist discloses (Figs. 1 – 4) an optical device (electro-absorption modulator (EAM); Abstract) wherein the attenuation rate and concomitant heat dissipation are flattened (as shown in Fig. 3) by using a tapered width of the rib/ridge waveguide (as shown in Fig. 4A). While Lundquist considers that the rib/ridge waveguide is contiguous along its entire length, Wipiejewski discloses (Figs. 1, 3, 5, and 7 – 9; Abstract; para. 0027 – 0040) an optical device/EAM (which is the same device type as that in Lundquist and Yegnanarayanan) that comprises a segmented waveguide with a plurality of waveguide segments 20 with high optical absorption that are interleaved with a plurality of waveguide segments 18 with low optical absorption, the plurality of waveguide segments 20 having lengths increasing along the light propagation direction so that the attenuation rate and concomitant heat dissipation are flattened (as shown by curve 32 in Fig. 7).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the EAM of the Lundquist – Yegnanarayanan combination can be modified, in accordance with the teachings of Wipiejewski, to have a segmented waveguide with a plurality of waveguide segments with high optical absorption and varying lengths (increasing towards the EAM output) in order to provide more flexibility in distributing heat dissipation long the waveguide/modulator length.
The Lundquist – Yegnanarayanan – Wipiejewski combination considers an EAM comprising segmented waveguide with a plurality of waveguide segments with high optical absorption and varying lengths (increasing towards the EAM output). Different segment lengths result in different cross-sectional areas under electrodes 34 (Fig. 8 of Wipiejewski), different resistances, and different currents flowing through different waveguide segments, with shorter electrodes having less current flowing through them due to smaller cross-sectional areas. Hence, the optical absorption structure has a structure that makes an electric current flowing between the first electrode and the second electrode in the optical input portion (with shorter waveguide segments 20) smaller than the electric current in an optical output portion (with longer waveguide segments 20) of the rib optical waveguide and thereby makes the signal light passing through the optical input portion lower in optical attenuation rate than the signal light passing through at least the part of the rib optical waveguide, the part excluding the optical input portion.
Regarding claim 9, the Lundquist – Yegnanarayanan – Wipiejewski combination considers that the optical absorption structure has an (central) undoped optical waveguide that is an optical waveguide in the rib optical waveguide between the P doped region and the N doped region (as shown in Fig. 1 of Yegnanarayanan). The Lundquist – Yegnanarayanan – Wipiejewski combination renders obvious embodiments wherein at least one of the central region and the doped slab regions is tapered. The direction of up-tapering can be from the input portion to the output portion or reversed by properly selecting waveguide segments (according to Wipiejewski) for the same benefit/purpose of flattening heat release/distribution along the waveguide length.
Claims 6 and 7 are rejected under 35 U.S.C. 103 as being unpatentable over Lundqvist in view of Yegnanarayanan, and further in view of Cho et al (US 2022/0137440 A1).
Regarding claim 6, while the Lundquist – Yegnanarayanan combination illustrate only embodiments with a single doped region on either side of the undoped central region (as in Fig. 1 of Yegnanarayanan). Cho discloses (Fig. 5; para. 0048 – 0050) an optical modulator comprising a ridge waveguide comprising a thicker central region 530,560 flanked by a plurality of thinner slab regions 510,522,524,526,556,554,552,540 doped with opposite polarities, wherein the doping concentration increases going away from the central region 530,560.
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the EAM of the Lundquist – Yegnanarayanan combination can further comprise, in accordance with the teachings of Cho, additional doped regions with higher doping concentrations (P++ and N++), in order to reduce optical loss caused by heavily doped outer doped regions while keeping low resistance (para. 0050 of Cho).
In the EAM of the Lundquist – Yegnanarayanan – Cho combination, the P doped region has a P+ doped region formed near a core of the rib optical waveguide and a P++ doped region connected to the first electrode, and the N doped region has an N+ doped region formed near the core of the rib optical waveguide and an N++ doped region connected to the second electrode.
Regarding claim 7, the Lundquist – Yegnanarayanan – Cho combination considers a rib/ridge waveguide with a width tapered along the direction of light propagation (as in Fig. 4A of Lindquist) and a plurality of doped regions with doping concentrations increasing going away from the central region. The Lundquist – Yegnanarayanan – Cho combination renders obvious embodiments wherein at least one of the central region and the doped slab regions is tapered. In the latter case, the P+ doped region gradually increases in width from an optical output portion to the optical input portion of the rib optical waveguide; and the N+ doped region gradually increases in width from the optical output portion to the optical input portion, which would make an electric current flowing between the first electrode and the second electrode in the optical input portion lower than the electric current in the optical output portion and thereby makes the signal light passing through the optical input portion lower in optical attenuation rate than the signal light passing through at least the part of the rib optical waveguide, the part excluding the optical input portion (as intended by the Lundquist – Yegnanarayanan – Cho combination).
Allowable Subject Matter
The subject matter pertaining to claims 3 – 5 would be allowable, if Applicant rewrites them in independent form including all of the limitations of the base claims and any intervening claims.
The reason for indicating allowable subject matter is that none of the prior art of record, taken alone or in combination, teaches expressly, renders obvious, and provides a motivation for an optical device/EAM wherein an electrode pad is arranged near the output portion of the optical waveguide and/or wherein electrodes are tapered (as shown in Figs. 1, 3, 5B, 7, and 9 of the instant application) in order to reduce electrical current flowing through the input portion of the optical waveguide and thereby make heat dissipation/distribution more uniform along the waveguide length.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2016/0377953 A1
US 9,823,497 B1
US 12,176,677 B2
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/ROBERT TAVLYKAEV/Primary Examiner, Art Unit 2896