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
Claim 15 recites the limitation “are related to one another by Fresnel's equation”, while the instant specification defines (para. 0050 and 0051) such “Fresnel's equation” as Snell’s law and misnames the latter. As is well known, the Fresnel equations are for the amplitude coefficients (Fresnel coefficients) of transmission and reflection at the interface between two transparent homogeneous media. The directions of incident and refracted light at the interface are governed by Snell’s law.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 8, and 9 are rejected under 35 U.S.C. 102(a)(2) as being anticipated by Mahgerefteh et al (US 2016/0131837 A1).
Regarding claim 1, Mahgerefteh discloses (Fig. 32; para. 0224 – 0228) an optical coupler comprising:
a silicon substrate (shown as 3102 in Fig. 31A; para. 0213);
a silicon nitride waveguide 3202 (para. 0225) positioned on the silicon substrate, the silicon nitride waveguide 3202 configured to guide an optical signal 3210 (multimode input optical signal; para. 0225) along a first (horizontal) axis; and
a silicon waveguide 3204 (para. 0226) positioned on the silicon substrate, wherein the silicon waveguide 3204 is configured to receive, from an output (right/tapered) end 3208 of the silicon nitride waveguide 3202, the optical signal at an input (left) end of the silicon waveguide 3204 and guide the optical signal along a second (horizontal) axis that is at a first (zero) angle to the first (horizontal) axis.
As an aside, it is noted that claim 1 has a broad scope that covers both a non-zero value and a zero value of the first angle. On the contrary, claim 10 limits the first angle to non-zero values.
Regarding claims 8 and 9, Mahgerefteh teaches (Fig. 14) that the optical coupler (coupling a silicon nitride waveguide 1404A to a silicon waveguide 1408A; para. 0139) is positioned between a demultiplexer 1400 (“AWG 1400 that may be formed as a passive optical device such as a WDM component (e.g., a WDM mux or WDM demux)” at para. 0139) and a photodiode (“An example output device to which output may be sent may include a laser, an optical receiver (e.g., a photodiode) … one or more of the active optical components of the Si PIC 102 may be configured to receive and process incoming signals that are inputted to the photonic system 200 through the interposer waveguide, the SiN waveguide, and the Si waveguide” at para. 0080, emphasis added), wherein the silicon nitride waveguide 1404A is an output waveguide of the demultiplexer 1400 (as seen in Fig. 14).
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 2 – 4 are rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh in view of Lin et al (CN 115047564 A).
Regarding claim 2, Mahgerefteh illustrates (Figs. 31A and 32) only embodiments of the vertically-stacked coupler wherein the ends of the silicon waveguide and the silicon nitride waveguide have a single taper/finger and Mahgerefteh does not teach that the ends can have a plurality of fingers of a comb. However, Lin discloses (Figs. 1 – 7) an optical coupler comprising vertically-stacked and optically-coupled waveguides 100,20/30,200 and teaches both an embodiment (Fig. 1; para. 0002) with a single taper at each end of a (intermediate) waveguide 20 and embodiments (Fig. 5, 7, and 8; para. 0018 – 0023) wherein at least one waveguide end of one or more coupled waveguides includes a plurality of fingers of a comb (identified as fingers 31 for the (intermediate) waveguide 30 in Fig. 5).
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 (tapered) input end of the silicon waveguide (end 3214 in Fig. 32 in Mahgerefteh) can be modified, in accordance with the teachings of Lin, to include a plurality of fingers of a comb. The motivation for such fingers (“sub-portions”) is that they produce a gradient profile of refractive index and thereby further reduce back-reflections (“a plurality of sub-portions extending through the bifurcation, and the sub-portion has a tapered surface, on the one hand can reduce the possible reflection” at para. 0019 of Lin). As seen in Fig. 5 of Lin, the plurality of fingers 31 are vertically arranged and aligned orthogonally to the second (horizontal) axis.
Regarding claims 3 and 4, the Mahgerefteh – Lin combination renders obvious that at least one waveguide end of any one of the coupled waveguides can include a plurality of fingers of a comb. In particular, the output end of the silicon nitride waveguide (end 3208 in Fig. 32 in Mahgerefteh) can include a plurality of fingers of a comb, wherein the fingers of the comb are vertically arranged and aligned orthogonally to the second (horizontal) axis.
Claims 5 – 7 are rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh.
Regarding claim 5, Mahgerefteh illustrates (Figs. 3A and 12B) embodiments wherein the output end of the silicon nitride waveguide 208 terminates at a second (zero) angle from a (vertical) plane that is orthogonal to the first (horizontal) axis. Hence, Mahgerefteh renders obvious that, in the embodiment in Fig. 32, the output end of the silicon nitride waveguide 3202 can also terminate at a second (zero) angle from a (vertical) plane that is orthogonal to the first (horizontal) axis.
Regarding claim 6, Mahgerefteh renders obvious that the first (zero) angle and the second (zero) angle are based on one another in order to ensure angular alignment of the longitudinal axes (by a zero first angle) and the phase fronts of the modes of the two coupled waveguides (by a zero second angle).
Regarding claim 7, Mahgerefteh teaches (para. 0223) that the coupler can be configured as a multi-mode coupler in which the waveguide supports multiple modes of one or both orthogonal polarizations (TE and TM) and renders obvious that the coupler design, including the first angle and the second angle, can be based/configured on a plurality of modes of the optical signal.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh in view of Chen et al (US 2019/0293881 A1).
Regarding claim 10, Mahgerefteh discloses (Fig. 32; para. 0224 – 0228) an apparatus (optical coupler) comprising:
a first layer comprising silicon (a silicon substrate shown as 3102 in Fig. 31A; para. 0213);
a second layer 3202 comprising silicon and nitrogen (a silicon nitride waveguide; para. 0225), the second layer 3202 on the first layer 3102, wherein the second layer has a first (longitudinal) axis that defines a first (right) end and a second (left) end of the second layer 3202; and
a third layer 3204 comprising silicon (a silicon waveguide; para. 0226), the third layer 3204 on the first layer 3102, wherein the third layer 3204 has a second (longitudinal) axis that defines a first (left) end and a second (right) end of the third layer, and wherein the first end 3208 of the second layer 3202 is adjacent to the first end 3214 of the third layer 3204.
Mahgerefteh discloses only embodiments wherein the longitudinal axes of the second layer 3202 (silicon nitride waveguide) and the third layer 3204 (silicon waveguide) are parallel to each other so that the first axis and second axis are at a zero first angle to one another. Mahgerefteh does not teach that the two waveguides can be disposed at a non-zero first angle between their longitudinal axes. However, Chen discloses (Figs. 1, 2, and 4A – 4F; Abstract; para. 0039 – 0054) an optical coupler comprising two waveguide cores 310,330 are that optically coupled to each other and disposed at a non-zero first angle between their longitudinal axes (“In each of FIGS. 4A-4F, the propagation axis of the first waveguide core 310 is oriented at a non-zero angle relative to the propagation axis of the third waveguide core 330” at para. 0048).
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 longitudinal axes of the second layer 3202 (silicon nitride waveguide) and the third layer 3204 (silicon waveguide) in Mahgerefteh can be reoriented to have a non-zero angle between each other, as a suitable/workable design choice that is illustrates by Chen and can accommodate optical waveguide connection between the coupler and other optical devices (e.g., photodetectors 210,220 in Fig. 2 of Chen; para. 0033) that may be disposed at different spatial locations on the silicon substrate.
Claims 11 – 13 are rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh in view of Chen, and further in view of Lin.
Regarding claims 11 – 13, the teachings of Mahgerefteh, Chen, and Lin combine (see the arguments and motivation for combining, as provided above for claims 2 and 10) to teach expressly or render obvious all of the recited limitations, as detailed above for claims 2 – 4 and 10.
Claims 14 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh in view of Chen, and further in view of Mino et al (JP 2003-207664).
Regarding claim 14, the Mahgerefteh – Chen combination does not consider that waveguide ends can be slanted/non-perpendicular relative to longitudinal axes. However, Mino discloses (Fig. 1; Abstract; para. 0013 –0015) a pair of optically coupled waveguides 4,5 that are formed in materials with different refractive indices and have waveguide ends that are slanted/non-perpendicular relative to the longitudinal axes, so that an output end of a first waveguide 4 terminates at a non-zero second angle q from a plane (perpendicular to the plane of Fig. 1 and the longitudinal axis of the waveguide 4) that is orthogonal to a first (horizontal) axis. 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 first (output) end of the second layer (silicon nitride waveguide) can be slanted and terminate at a non-zero second angle from a plane that is orthogonal to the first (horizonal/longitudinal) axis. The motivation for slanted waveguide ends is that (undesirable) back-reflections ae minimized (Fig. 2; Abstract; para. 0016 and 0017 of Mino).
Regarding claim 15, the Mahgerefteh – Chen – Mino combination considers that the first angle and the second angle are related to one another by Snell’s law governing directions of incident and refracted light (Snell’s law is misnamed by Fresnel's equation, as detailed above in the Section “Claim Interpretation”) and are related to the refractive indices of silicon nitride and silicon (Abstract and para. 0015 of Mino).
Claims 16 – 20 are rejected under 35 U.S.C. 103 as being unpatentable over Mahgerefteh in view of Ilda et al (US 2019/0391325 A1).
Regarding claim 16, Mahgerefteh discloses an embodiment (Fig. 23A; para. 0165 – 0168) wherein waveguides 2312 are bent in a vertical/thickness direction. While Fig. 23A shows waveguides 2312 formed in an interposer 2304, Mahgerefteh generally renders obvious that the silicon nitride waveguide 3202 in Fig. 32 can be modified from a planar form in a similar fashion and include a bend in a vertical/thickness direction. While Mahgerefteh does not expressly teach that a bend in a vertical/thickness direction can be monolithically formed in a same chip, Ilda discloses (Figs. 4, 5, and 18; Abstract; para. 0072 – 0081 and 0127 – 0129) an optical coupler comprising two optical waveguides WG1,WG2, wherein one waveguide WG1 has a bend in a vertical/thickness direction, the bend monolithically formed in a same chip (according to the processing steps in Figs. 11 – 18).
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 silicon nitride waveguide 3202 in Fig. 32 can be modified/bent, in accordance with the teachings of Ilda, from a planar form to include a bend in a vertical/thickness direction so that the height difference (in the vertical/thickness direction) between the silicon nitride waveguide 3202 and the silicon waveguide 3204 varies from the largest value at the input of the silicon nitride waveguide 3202 to the smallest value (possibly zero) at the output of the silicon nitride waveguide 3202 (where it directly contacts the top surface of the silicon waveguide, in accordance with Figs. 5 and 18 of Ilda). In such embodiment, the optical coupler comprises:
a silicon substrate (shown as 3102 in Fig. 31A; para. 0213);
a silicon waveguide 3204 separated from the silicon substrate 3102 by an oxide layer 3120 (as identified in Fig. 31A; para. 0213), wherein the oxide layer has a first thickness between the silicon substrate and the silicon waveguide; and
a silicon nitride waveguide 3202 configured to receive an optical signal 3210 from an optical source and output the optical signal 3210 to the silicon waveguide 3204, wherein the silicon nitride waveguide 3202 includes:
a first (input) portion, wherein the first portion is separated from the silicon substrate 3102 by the oxide layer 3120, and wherein the oxide layer 3120 has a second thickness (larger thickness due to a vertical bend) between the silicon substrate 3102 and the first (input) portion of the silicon nitride waveguide 3202; and
a second (output) portion adjacent to the silicon waveguide 3204, wherein the second (output) portion is separated from the silicon substrate 3102 by the oxide layer 3120, and wherein the oxide layer 3120 has the first thickness between the silicon substrate 3102 and the second (output) portion of the silicon nitride waveguide 3202 (if the second (output) portion directly contracts the silicon waveguide 3204 and there is not residual oxide layer therebetween).
As an aside, it is noted that the embodiment in Fig. 23A of Mahgerefteh has substantially structural features (a bend in a vertical/thickness direction configured to bring two optical waveguide cores into proximity/contact and thereby enable optical coupling) that are similar to those in Fig. 5 of the instant application. It is also noted that claim 16 does not have limitations defining butt/endfire coupling (as in Fig. 10) and has a broader scope covering both embodiments in Figs. 5 and 10.
Regarding claim 17, in the embodiment with a bend in the vertical/thickness direction (as detailed above for claim 16), the silicon nitride waveguide has a third (intermediate) portion positioned between the first portion and the second portion (corresponding to the shape of waveguides 2312 in Fig. 23A), wherein the second portion and the third portion are sloped at an angle from the second thickness to the first thickness to form the bend in the vertical/thickness direction.
Regarding claim 18, the bend in the vertical/thickness direction can have a fourth portion positioned between the second portion and the third portion, and wherein the oxide layer has the first thickness between the silicon substrate and the silicon nitride waveguide. Determination of a suitable/workable shape of the bend would be well within ordinary skill in the art.
Regarding claim 19, a suitable/workable range of values of the angle of the bend is determined by a particular application (e.g., an acceptable bending loss, a wavelength of operation, a particular selection of materials and their refractive indices, etc). Determination of a suitable/workable shape of the bend, including the angle of inclination, would be well within ordinary skill in the art.
Regarding claim 20, while Mahgerefteh states, by way of example but not limitation, the silicon nitride waveguide has a thickness that is greater than a thickness of the silicon waveguide (para. 0091 and 0103), an optimum thickness of each waveguide is determined by its refractive index, its width, a desired shape of the waveguide mode. A wider waveguide can be thinner for the same selection of materials and the number of supported modes. Mahgerefteh’s teachings place no requirement on the difference between the thicknesses of the silicon nitride waveguide the silicon waveguide and renders obvious that such difference can be negative, zero or positive, as a matter of suitable/workable design choice.
As an aside and relative comment, it is noted that the instant application does not disclose any unexpected benefit associated with the silicon nitride waveguide being thinner than the silicon waveguide. In fact, the instant specification states that “It will be noted that the thicknesses of the SiN waveguide 1020 and the Si waveguide 1040 are depicted as different than one another such that the SiN waveguide 1020 is thinner than the Si waveguide 1040. However, in other embodiments, the SiN waveguide 1020 may be thicker than, or have the same thickness as, the Si waveguide 1040” (para. 0065) which is in agreement with the above-noted facts of common knowledge in the art.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2018/0164501 A1
US 2018/0024299 A1
US 2024/0004140 A1
US 2022/0146749 A1
US 2009/0297093 A1
US 2008/0193079 A1
US 2019/0310423 A1
US 2023/0400652 A1
US 2019/0170941 A1
US 2014/0321801 A1
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