The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 8/28/26 has been entered. Claims 1 and 6 have been amended. Claims 1, 3, and 5 – 29 are pending.
Response to Amendments / Arguments
Applicant’s arguments regarding the previously raised claim rejections under 35 USC 103 have been fully considered but they are moot in view of the new grounds of rejections, as necessitated by Applicant’s amendments. Specifically, the new limitations in the independent claims define a thin substrate with a rib-type waveguide and a tapered-width waveguide within the coupling portion of the directional coupler. Accordingly, the Examiner has applied a reference by He et al (CN 111913309 A) that has been yielded by an updated prior art search and discloses a Mach-Zehnder modulator formed in thin-film lithium niobate and comprising input/output 3x3 directional couplers with tapered widths of the constituent waveguides. In combination with other prior art of record, He teaches expressly or renders obvious all of the limitations recited by the amended claims, as detailed below.
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.
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 CFR 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, 5 – 9, 16, and 17 are rejected under 35 U.S.C. 103 as being unpatentable over He et al (CN 111913309 A) in view of Jain (US 10,041,797 B2), and further in view of “An Electro-Optic 3x3 Switch Based On Integrated Mach-Zehnder Interferometer” by Rahman et al, Proceedings of the 8th WSEAS International Conference on Applied Electromagnetics, Wireless and Optical Communications, ISSN, vol. 2769, paper 1790, 2010 (hereinafter Rahman).
Regarding claim 1, He discloses (e.g., Figs. 1 – 3 and 9; Abstract; para. 0001 – 0016) an optical waveguide device (modulator/switch; Abstract) comprising (see annotated Fig.1 below):
an optical waveguide formed on a (lithium niobate) substrate 20 with a thickness of 1 mm or less (e.g., H = 130 nm; para. 0003) to have a protruding (ridge) shape of the substrate 20 to be used as a rib type waveguide (as seen in cross-sectional views in Figs. 2 and 3),
wherein a (3x3) directional coupler (at least one of the left 3dB splitter 1-6 and the right 3dB combiner 12-17) is disposed in a part of the optical waveguide (as seen in Fig. 1), the (3x3) directional coupler (e.g., the left 3dB splitter 1-6) includes one center waveguide 1,2 and two side waveguides (3,5 and 4,6 respectively) disposed to interpose the center waveguide 1,2 between the side waveguides (as seen in Fig. 1), the side waveguides (3,5 and 4,6) are disposed to be close to the center waveguide 1,2 at a (left) position and are separated from the center waveguide 1,2 in a traveling (e.g., left to right in Fig. 1) direction of a light wave, the center waveguide 1,2 and the side waveguides (3,5 and 4,6) are not in contact with each other (as seen in Fig. 1), the (3x3) directional coupler functions as a branching waveguide that introduces a light wave from one (left) side of the center waveguide 1,2 and that derives the light wave branching from the two side waveguides (3,5 and 4,6) positioned on the other (right) side of the center waveguide 1,2, a starting (left) end of each of the two side waveguides (3,5 and 4,6) is located on an input (left side) side of the (3x3) directional coupler, and an ending (right) end of the center waveguide 1,2 is located on an output (right) side of the (3x3) directional coupler, and
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a width (W1, as denoted in annotated Fig.1) of the center waveguide 1,2 (its portion 2) in a coupling portion (delimited by the length of the waveguide portion 2) of the directional coupler is set to be narrower (e.g., 100 nm; para. 0002) than a width (W2, e.g., 200 – 800 nm; para. 0002) of the center waveguide 1,2 (its portion) outside the coupling portion.
Annotated Fig. 1 of He.
Figure 1 of He illustrates, by way of example but not limitation, a waveguide layout wherein the left ends of the side waveguides (3 and 4) are disposed at the start of the coupling region and He does not illustrates a layout with converging portion of the waveguides 3,4 that precede the coupling region. However, Jain discloses (Figs. 3a and 3b; 6:10 – 51) a bidirectional 3x3 waveguide coupler 101 (comprising a center waveguide 107 and side waveguides 104,105) that has structural features similar to those in He and operates as an input splitter (going from a light source 109 to a fiber coil 110) and an output combiner (for the reverse direction of light propagation). Jain illustrates that the side waveguides 104,105 and the center waveguide 107 extend beyond the coupling region (of length L, as denoted in Fig. 3a) on both sides thereof. 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 side waveguides and the center waveguide in He can be modified to extend beyond the coupling region on both sides thereof, as generally suggested by He (Fig. 1 shows that the center waveguide and the side waveguides extend outside the coupling region on at least one side thereof) and explicitly illustrated by Jain, so that light can gradually transition in and out of the 3x3 directional coupler with an abrupt transition/disruption of the constituent waveguide paths.
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The optical waveguide device/modulator of the He – Jain combination is illustrated in Figure A below which is produced from Fig. 1 of He by exceeding the side waveguides and exendin the center waveguide beyond the coupling region on the other side thereof.
Figure A. The optical waveguide device/modulator of the He – Jain combination.
The He – Jain combination considers that, within the input/left/branching 3x3 directional coupler, the side waveguides are disposed to come close to the center waveguide (within the coupling portion) from a (left) position where the side waveguides are separated (by the input bends) from the center waveguide and then to be separated again from the center waveguide in the traveling direction (left to right) of the light wave.
The He – Jain combination considers that the center waveguide can start and end at positions at which the optical coupling between the center waveguide and each side waveguides is negligibly small, but the He – Jain combination does not illustrate a well-known fact that a pair of optical waveguides can be optically coupled to each other only within distances comparable to, or smaller than, a mode diameter of a light wave propagating through the optical waveguides. However, Rahman describes (Figs. 1 and 4; Abstract; Sections 1 and 2) an optical waveguide device/modulator that has structural features similar to those in He and comprises a 3x3 directional coupler as an input (left) splitter and a 3x3 directional coupler as an output (right) combiner. Rahman explicitly illustrates (Figs. 4a – 4c) that a light wave input into, and propagating through, the lower side waveguide of the input 3x3 directional coupler begins to couple over to the center waveguide only at a distance/separation (between lower side waveguide and the center waveguide) that is comparable to, or smaller than, a mode diameter (about 10 mm) of the light wave.
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 center waveguide starts and ends at positions at which the optical coupling between the center waveguide and each side waveguides is negligibly small, as considered by the He – Jain combination, wherein such positions correspond to a distance/separation (between the side waveguides and the center waveguide) that is comparable to, or smaller than, a mode diameter of the light wave, as illustrated by Rahman. In such layout, design, a distance between the center waveguide and the starting end of each of the side waveguides before coming close to the center waveguide and a distance between the ending end of the center waveguide and the side waveguides after being separated from the center waveguide are set to be substantially more (e.g., by 2 times) than a mode diameter of a light wave propagating through the optical waveguide, in order to ensure that the optical coupling between the center waveguide and each side waveguides is negligibly small at the start and end positions of the center waveguide and the optical coupling is gradually increased going into the coupling portion and then gradually tapered off after the coupling portion.
In light of the foregoing analysis, the He – Jain – Rahman combination teaches expressly or renders obvious all of the recited limitations.
Regarding claim 6, the teachings of He, Jain, and Rahman 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, as detailed above for claim 1. Specifically, the He – Jain – Rahman combination considers an optical waveguide device (modulator of a Mach-Zehnder type with 3x3 directional couplers for the splitter and combiner) comprising (see annotated Fig. 1 of He and Figure A provided above for claim 1):
an optical waveguide formed on a (lithium niobate) substrate 20 with a thickness of 1 mm or less (e.g., H = 130 nm; para. 0003 of He) to have a protruding (ridge) shape of the substrate 20 to be used as a rib type waveguide (as seen in cross-sectional views in Figs. 2 and 3),
wherein a (3x3) directional coupler (at least one of the left 3dB splitter 1-6 and the right 3dB combiner 12-17) is disposed in a part of the optical waveguide (as seen in Fig. 1), the (3x3) directional coupler includes one center waveguide (Fig. 1 and Figure A) and two side waveguides disposed to interpose the center waveguide between the side waveguides,
the side waveguides are disposed to come close to the center waveguide from a (left) position where the side waveguides are separated from the center waveguide and then to be separated again from the center waveguide in a traveling direction (left to right) of a light wave, the center waveguide and the side waveguides are not in contact with each other,
the (3x3) directional coupler (the right 3dB combiner 12-17) functions as a combining waveguide that introduces two light waves into each side waveguide from the one side of the two side waveguides and that derives a light wave into which the two light waves are combined from the center waveguide positioned on the other side of the side waveguides,
a starting end of the center waveguide is located on an input (inner/left) side of the directional coupler 12-17, and an ending (outer/right) end of each of the side waveguides is located on an output (outer/right) side of the directional coupler,
a distance between the starting end of the center waveguide and each of the side waveguides before coming close to the center waveguide and a distance between the center waveguide and the ending end of each of the side waveguides after being separated from the center waveguide (by/along the output bends, as suggested by Jain) are set to be twice or more of a mode diameter of a light wave propagating through the optical waveguide (as illustrated by Radham and detailed above for claim 1), and
a width of the center waveguide in a coupling portion of the directional coupler is set to be narrower than a width of the center waveguide outside the coupling portion (as taught by He and detailed above for claim 1).
Regarding claims 3 and 17, the He – Jain – Rahman combination considers that an intensity of optical confinement of the optical waveguide in any of the center waveguide or the side waveguides is weaker/looser in a state (with the coupling portion) where the center waveguide and the side waveguides are close to each other than in a state where the center waveguide and the side waveguides are separated from each other (at the input and output of each 3x3 directional coupler): He considers that the center waveguide is narrower within the coupling portion (as detailed above for claim 1) which leads to weaker/looser optical confinement. Furthermore, the center waveguide and the side waveguides are in proximity of one another within the coupling portion which leads to their evanescent tails spreading out and overlapping, as seen in Figs. 4a – 4c of Rahman.
Regarding claims 5 and 7, the He – Jain – Rahman combination considers that the optical waveguide device further comprises an unnecessary light beam removing unit (absorber 114 in Fig. 3 of Jain) that causes a light wave propagating through the center waveguide to be absorbed or to be radiated outside the optical waveguide device is provided on the output side of the directional coupler.
Regarding claim 8, the He – Jain – Rahman combination considers that the optical waveguide device further comprises a guide unit (the left portion of 104,105 in Fig. 3a of Jain) that guides at least a part of a light wave propagating through the side waveguides 104,105 to a photo detection unit 102,103 (6:10 – 41) is provided on the output side of the 3x3 directional coupler 104,105,107.
Regarding claims 9 and 16, the He – Jain – Rahman combination considers that the optical waveguide includes a Mach-Zehnder type optical waveguide (taught by He and Rahman), and the directional coupler is incorporated in a Y-junction (in each of the branching part and the combining part) of the Mach-Zehnder type optical waveguide.
Claims 10 – 15 are rejected under 35 U.S.C. 103 as being unpatentable over He in view of Jain, in view of Rahman, and further in view of Sugiyama (US 2013/0243363 A1).
Regarding claims 10 and 13, the He – Jain – Rahman combination considers a Mach-Zehnder type optical waveguide comprising 3x3 directional couplers as input and output couplers (as detailed above for claims 1, 6, 9, and 16). While the He – Jain – Rahman combination does not detail further structural particulars (such as a case/housing) and high-speed applications of such device, Sugiyama discloses (Figs. 1, 5, 8 and 10; para. 0019 – 0021, 0049 – 0054, 0059 and 0069) a Mach-Zehnder type optical waveguide that is configured for a high-speed modulator (Fig. 6; para. 0005) and formed by couplers 2,5. Sugiyama expressly teaches that the modulator device comprises a case accommodating the optical waveguide device (para. 0059 and 0060); and an optical fiber 64 (shown in Fig. 10; para. 0060) through which a light wave is input into the optical waveguide or output from the optical waveguide.
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 Mach-Zehnder type optical waveguide comprising 3x3 directional couplers as input and output couplers, as contemplated by the He – Jain – Rahman combination, can be implemented as a high-speed modulator, as a suitable/workable application illustrated by Sugiyama. The device is accommodated/disposed in a case in order to be sealed from an environment and be mechanically rugged.
Regarding claims 11, 12, 14, and 15, the He – Jain – Rahman – Sugiyama combination considers that the optical waveguide device (high-speed modulator) includes a modulation electrode (9,10,11 in Fig. 1 of He; para. 0002 and 0005 – 0007; also para. 0021 and 0033 – 0036 of Sugiyama) for modulating a light wave propagating through the optical waveguide, wherein the modulation electrode is driven by an electronic circuit 63 (Fig. 10 of Sugiyama; “an electrical signal output from a driver amplifier of the data generation circuit 63 is provided to the electrodes on the chip of the optical modulator” at para. 0060) that amplifies a modulation signal to be input into the modulation electrode of the optical waveguide device (para. 0021, 0059, and 0060 of Sugiyama) and is provided inside the case of the transmitting device 61. 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 optical waveguide device (high-speed electro-optic switch/modulator) of the He – Jain – Rahman – Sugiyama combination can be co-packaged with an electronic circuit 63 (driver amplifier) that amplifies a modulation signal for more optical modulation and enables an integrated transmitting module.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
JP 2006-65089 Figs. 4,6, and 7 show directional couplers with waveguide widths tapered down in coupling regions to improve/broaden spectral bandwidth.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ROBERT TAVLYKAEV whose telephone number is (571)270-5634. The examiner can normally be reached 10:00 am - 6:00 pm, Monday - Friday.
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/ROBERT TAVLYKAEV/Primary Examiner, Art Unit 2896
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