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
Applicant’s remarks filed 7/10/25 are acknowledged. No claims have been amended. Claims 15 – 28 are pending.
Response to Arguments
Applicant’s arguments regarding the amended claims versus the previously raised claim rejections under 35 USC 103 based on the Kissa – Manouvrier combination have been fully considered but they are not persuasive, as detailed below.
Claim 15:
(a) Applicant argues that “Even though electro-optic phase shifters comprising abutted P- or N-type junctions are known from references such as Manouvrier and Zhou (US 10,416,525, also cited as relevant in the Office Action, p. 2), their introduction into the architecture of Kissa would not be obvious to a person skilled in the art as one of ordinary skill in the art would not be motivated to do so. In Kissa, the optical waveguides are consistently depicted as physically separated in all figures, and this separation is explicitly emphasized in multiple paragraphs, including Kissa, paragraphs [0020] and [0036]” (para. bridging pp. 7 – 8 of the Remarks).
The Examiner respectfully disagrees and notes the following:
(i) Applicant mistakes the waveguides shown in the drawings in Kissa for the entire modulator structure, including undoped/lightly-doped waveguide cores that are sandwiched between heavily-doped regions for electrical connections (as shown in Fig. 4A of of Manouvrier).
The ridge-shaped waveguide cores 12a,12b in Figs. 4A, 5, and 7A of Manouvrier are spatially separate and optically decoupled from each other, as required for proper operation of a Mach-Zehnder interferometer which comprises the ridge-shaped waveguides as the interferometer arms/branches 12a,12b (as shown in Fig. 5). The heavily-doped regions p+,n+ (providing electrical connections) that are connected to provide a continuous electrical path, as needed for electro-optic modulation, not for optical guiding. Applicant mistook the heavily-doped regions p+,n+ for optical waveguides, while the optical and electrical elements are quite different, both structurally and in terms of their functionalities.
Applicant is expected to have at least the level of ordinary skill in the art of optical waveguide modulators (which is noted as being high) and possess knowledge of such basic/trivial /textbook facts.
(iii) The core teaching of Kissa is the use of passive waveguide segments and/or waveguide crossings for quasi-phase-matching in an electro-optic waveguide modulator. It is noted that quasi-phase-matching is a technique well known the art since at least the early 80s (e.g., the NPL reference by Alferness) and is the same as that adopted by the instant application.
Quasi-phase-matching can be implemented in any material used for optical waveguides. Not surprisingly, Kissa states (para. 0013) that the disclosed modulator can be implemented in a variety of materials, including semiconductor materials, such as silicon (“an electrical-optical modulator may employ silicon photonics, polymer, lithium niobate, thin lithium niobate, or gallium arsenide technologies” at para. 0013).
(b) Applicant argues that “These passages describe minimum spacing between the waveguides (e.g., at least 10 m), and reference distinct routing of modulation and delay sections. The expression "separated by at least 10 m" in paragraph [0020] of Kissa refers to the physical lateral spacing between the first and second waveguides (104a, 104b), indicating that the optical cores are laid out at a substantial distance from each other on the photonic chip” (1st complete para. on p. 8).
The Examiner notes that Applicant’s argument is moot because it is based on Applicant’s mistake in distinguishing waveguide cores from heavily-doped regions for electrical current. Figures 4A, 5, and 7A of Manouvrier clearly show that the ridge-shaped waveguide cores are separated from each other by a distance. Such distance must be large enough to preclude optical coupling between the arms/branches 12a,12b of a Mach-Zehnder interferometer comprising the ridge-shaped waveguides, as required for its proper operation.
(c) Applicant further asserts that “Kissa thus teaches away from the abutted doping layout required by claim 15, "wherein the pair comprises two PN-junctions with abutted N-regions or with abutted P-regions."” (2nd complete para. on p. 8).
The Examiner respectfully disagrees and notes that Applicant’s assertion is fundamentally flawed because it is based on the same incorrigible and trivial failure to properly distinguish waveguide cores from doped regions for electrical current. The waveguide cores are separated by a minimum distance that must be large enough to preclude optical coupling between the arms/branches 12a,12b of a Mach-Zehnder interferometer comprising the ridge-shaped waveguides. The doped regions for electrical current may be either separated by a gap (for an electrode structure with 4 electrical contacts) or contact/abut each other (for an electrode structure with 3 electrical contacts).
(d) Applicant further asserts “the Office Action's proposed modification of the system of Kissa in view of Manouvrier relies on improper hindsight and disregards the fundamental design principles of Kissa so as to change the principle of operation of the system of Kissa and cause the system of Kissa to be unsatisfactory for its intended purpose” (1st para. on p. 7).
The Examiner respectfully disagrees and notes the following:
(i) The principle of operation in Kissa is electro-optic modulation with quai-phase-matching and it is maintained irrespective of a particular material(s) in which the modulator is implemented, as detailed above for item (a).
(ii) Kissa has a CIP application (published as US 2021/0080797 A1) of the same/common parent provisional application 62/901,504 as US 2021/0080796 A1. The invention in US 2021/0080797 A1 is also an electro-optic modulator with quai-phase-matching and details its implementation in semiconductor materials in doped regions and PN junctions. Figures 1 – 4 and 6A each show separate waveguide cores 104a,104b in a Mach-Zehnder interferometer, while Fig. 6C details a modulator cross-section in semiconductor materials and shows spatially separate ridge-shaped waveguide cores 604a,604b and doped regions p+,p++,n+,n++ are abutted to one another for a continuous current path for electrical current (para. 0083 – 0086). The ridge-shaped waveguide cores 604a,604b are driven by a 3-electrode structure 602a,602b,608a in full analogy with Fig. 7A of Manouvrier wherein the ridge-shaped waveguide cores 12a,12b are driven by a 3-electrode structure Ca,Cb,A.
Figure 6C of the CIP reference by Kissa is substantially identical to the cross-section in Figs. 15 and 16 of the instant application and defined by claim 15. Thus, even the CIP reference of Kissa (US 2021/0080797 A1) highlights the fundamental flaws in Applicant’s arguments and squarely refutes the alleged unsuitability of a doped structure with abutted regions in the modulator of Kissa (US 2021/0080796 A1).
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 15, 16, 20, 23, 26, and 28 are rejected under 35 U.S.C. 103 as being unpatentable over Kissa et al (US 2021/0080796 A1) in view of Manouvrier (US 2014/0341499 A1).
Regarding claim 15, Kissa discloses (Fig. 3; para. 0003 – 0006 and 0026 – 0029) an electro-optic Mach-Zehnder modulator 300 (“The set of coplanar waveguides can be part of a Mach-Zehnder (MZ) interferometer” at para. 0003) comprising (see annotated Fig. 3 below):
a first optical waveguide 304a and a second optical waveguide 304b (“a first optical waveguide 304a, and a second optical waveguide 304b” at para. 0026),
an optical (left) splitter configured for splitting an incoming optical signal in a first optical signal over the first optical waveguide 304a and a second optical signal over the second optical waveguide 304b and an optical (right) combiner configured for combining the optical signals from the optical waveguides (“an optical splitter may split an input optical signal to a first waveguide and a second waveguide of the electrical-optical modulator, and an optical combiner may combine an output of the first waveguide and the second waveguide” at para. 0015),
a plurality of pairs of electro-optic phase shifters 308 (defined by upper and lower electrode segments), for each pair one phase shifter per optical waveguide (as seen in Fig. 3), distributed over a length of the optical waveguides (along the horizontal direction in Fig. 3), each pair forming a segment of the modulator 300, wherein the electro-optic phase shifters 308 are configured for phase-modulating the optical signals by means of an electrical signal/voltage (“An electrical-optical modulator may be a modulator that uses a Pockels effect, an electro-optic effect, a quantum-confined Stark effect, a plasma dispersion effect, and/or the like, to change a phase of light under an applied voltage” at para. 0013; “Electrical signals of the electrodes 302 may interact with optical signals of the waveguides 304 via a plurality of segmented loading lines 308, as described above in connection with FIG. 1” at para. 0026, emphasis added), and
at least one crossing element (disposed within section L2) configured for crossing the optical waveguides 304a,304b between two segments (“in the second section L2, the time delay section 306a and the time delay section 306b may cross, to thereby redirect the first waveguide 304a to the second electrode 302b and the second waveguide 304b to the first electrode 302a” at para. 0028, emphasis added).
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Annotated Fig. 3 of Kissa.
Kissa states (para. 0013) that the disclosed modulator can be implemented in a variety of materials, including semiconductor materials (such as, silicon), but does not illustrate a suitable/workable design of semiconductor waveguides and, in particular, a design with two PN-junctions with abutted doped regions, even though such design/implementation is well known in the art of optical waveguide modulators. For example, Manouvrier discloses (Figs. 4 and 7; para. 0024 – 0034 and 0042 – 0047) an electro-optic Mach-Zehnder modulator (shown in Fig. 5) that comprises a first waveguide 12a and a second waveguide 12b formed in silicon (para. 0033) and receiving light from an optical splitter S and sending it to an optical combiner J; and a plurality of pairs of electro-optic phase shifters (defined by a plurality of opposing pairs of N+ regions and respective portions of the P+ region that create a plurality of phase-shifters along the longitudinal axis, as seen in Fig. 7B), each phase shifter per optical waveguide (as seen in Figs. 7A and 7B), wherein the electro-optic phase shifters are biased (para. 0003, 0028, and 0030) and configured for phase-modulating the optical signals by means of an electrical signal/voltage (para. 0002, 0021, 0033, and 0034). Manouvrier expressly teaches (Figs. 4A and 7A) a design wherein a pair of electro-optic phase shifters (modulating the first waveguide 12a and the second waveguide 12b) comprises two junctions between P and N doped regions (PN-junctions 14,18 in Fig. 4A (para. 0025); PIN-junctions in Fig. 7A (para. 0035)) with abutted P-regions (P+ doped regions of the left and right junctions form an abutted/common (inner) doped region P+), wherein biasing is done at a biasing node A (as identified in Fig. 7A) that is connected to, and associated with, the abutted P-region P+ (“The phase shifter includes two PIN junction shifters in opposition, sharing a contact area, here the P+ zone bearing an anode contact A. Each of the intrinsic regions I1, I2 of the two PIN phase shifters is associated with one of the waveguide branches 12a, 12b. The lateral N+ regions bear respective cathode contacts Ca, Cb” at para. 0042; “According to the sectional view of FIG. 7A, such a structure would suffice to independently adjust the static phase shift in each of the branches 12a and 12b, by applying separate control currents between terminal A and each of terminals Ca and Cb. However, to simplify the control of the dual phase shifter, a single control current may be used. The cathode contacts Ca and Cb are then electrically connected to each other (by a metal track not shown) so that the control current is distributed between the anode A and each of the cathode contacts Ca and Cb. In this case, without taking further design measures, the optical phase shift introduced by each of the zones I1 and I2 would be the same” at para. 0043).
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 electro-optic Mach-Zehnder modulator of Kissa can further comprise, in accordance with the teachings of Manouvrier, at least one biasing circuit configured for biasing the electro-optic phase shifters of a pair of the pairs of electro-optic phase shifters, wherein the pair comprises two PN-junctions with abutted N-regions or with abutted P-regions, and wherein biasing is done at a biasing node associated with the abutted N-regions or with the abutted P-regions, as a suitable/workable design choice that is expressly taught by Manouvrier and has the benefit of reducing the number of electrical connections/contacts for biasing from 4 (two contacts for each waveguide in the waveguide pair) down to 3 (two outer contacts Ca,Cb and one shared/common contact A at the inner abutted/shared region, as shown in Fig. 7A).
In light of the foregoing analysis, the Kissa – Manouvrier combination teaches expressly or renders obvious all of the recited limitations.
Regarding claim 16, Kissa expressly teaches (Fig. 3) that the electro-optic Mach-Zehnder modulator further comprises at least one delay element 306a,306b configured for delaying the optical signals between two segments (before and after the delay element) (“a time delay section 306a (associated with L2) … a time delay section 306b (associated with L2)” at para. 0027).
Regarding claim 20, Kissa expressly teaches that the at least one delay element 306a,306b comprises an optical building block configured for introducing optical delay (Abstract; para. 0027).
Regarding claim 23, Kissa expressly teaches that, in operation, the electrical and optical signal are propagating in the same direction 310 (“The electrodes 302 may be configured to propagate an electrical signal in a direction of propagation 310 of the electrical-optical modulator 300, and the waveguides 304 may be configured to propagate an optical signal in the direction of propagation 310” at para. 0026).
Regarding claim 26, while Fig. 3 of Kissa shows, by way of illustration but not limitation, one crossing element and one delay element per the entire modulator 300, it would be obvious to a person of ordinary skill in the art that a larger number of crossing elements and delay elements can be used, as a suitable/workable design choice to add flexibility in designing/tailoring/shaping the frequency response of the modulator, including a design choice wherein a crossing element or a delay element is present between each of the adjacent segments.
Regarding claim 28, Kissa discloses a method for designing a Mach-Zehnder modulator 300 (Fig. 3; para. 0003 – 0006 and 0026 – 0029), the method comprising introducing at least one crossing element between segments of the modulator 300 (see annotated Fig. 3 provided above for claim 1) in order to obtain a predefined transfer function (frequency response; “According to some implementations, an electrical-optical modulator may include one or more phase delay sections; and one or more modulation polarity reversal sections, the electrical-optical modulator having a frequency response characterized by a modulation bandwidth above a threshold value” at para. 0005; “in some implementations, the first section L1, the third section L3, or one or more additional sections providing modulation may additionally, or alternatively, include a time delay of an electrical signal of an electrode. In this way, the electrical-optical modulator may have a frequency response characterized by a modulation bandwidth that satisfies (e.g., is greater than) a threshold value (e.g., 60 gigahertz (GHz), 75 GHz, 80 GHz, or 85 GHz)” at para. 0017).
Claim 17 is rejected under 35 U.S.C. 103 as being unpatentable over Kissa in view of Manouvrier, and further in view of Sakane et al (US 2006/0028711 A1).
Regarding claim 17, while Fig. 3 of Kissa shows, by way of illustration but not limitation, a symmetric Mach-Zehnder interferometer (passively biased at 0 degrees), (asymmetric) Mach-Zehnder interferometers passively biased/shifted at 90o (quadrature point) are also well known in the art. For example, Sakane discloses (Figs. 7, 8, and 10; para. 0075 – 0080) an electro-optic Mach-Zehnder modulator comprising two waveguide arms 41,42 that are connected by an optical splitter at one (left) end and an optical combiner at the other (right) end. Sakane expressly teaches that the Mach-Zehnder interferometer is passively biased/shifted at 90o (quadrature point; para. 0087) by inserting an asymmetry (such a high refractive index part 43), in one of the interferometer arms 41,42, the high refractive index part 43 inducing a 90o phase shift.
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 modulator of the Kissa – Manouvrier combination can be passively biased/shifted at 90o (quadrature point) by inserting, in accordance with the teachings of Sakane, a high refractive index part in one of the interferometer arms in order to induce a 90o phase shift and thereby passively bias the Mach-Zehnder interferometer to a linear portion of its transfer curve (as shown in Figs. 8 and 10 of Sakane) without any additional bias voltage which reduces DC drift and improves temporal stability of the Mach-Zehnder modulator (para. 0087 and 0088 of Sakane).
The high refractive index part 43 inducing a 90o phase shift can be disposed at any point/location along the interferometer arms 41,42, including either one of the two branches of the optical splitter or one of the two branches of the optical combiner.
In light of the foregoing analysis, the Kissa – Manouvrier – Sakane combination teaches expressly or renders obvious all of the recited limitations.
Claims 18, 21, 22, 25, and 27 are rejected under 35 U.S.C. 103 as being unpatentable over Kissa in view of Manouvrier, and further in view of Kato (US 2012/0251032 A1).
Regarding claims 18, 21, and 22, Kissa does not apply any constraints on the relative lengths of the individual segments and gaps/distances therebetween to any particular relationships with one another and, on a general level, renders obvious embodiments wherein the segments are equal or different from one another and, in particular, their lengths and gaps/distances therebetween may be identical or different.
Fig. 1 of Kissa shows what appears to be equal lengths of the segments and equal distances/spacing between adjacent segments, but Kissa does not expressly specify them. However, Kato discloses a Mach-Zehnder modulator (Figs. 1 and 6; para. 0050 – 0075, 0119, and 0120) with a plurality of pairs of electro-optic phase shifters (14 in Fig. 1; A1 – A4 in Fig. 5), each pair forming a segment of the modulator. Kato teaches both a design choice (Fig. 1) with equal lengths of the segments and equal distances/spacing between adjacent segments and a design choice (Fig. 4) with unequal lengths of the segments, wherein a length of the phase shifter is varying between the different pairs of phase shifters. 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 lengths of the segments and the distances/spacing between adjacent segments can be equal or different as suitable/workable design choices that are illustrated by Kato and provide additional flexibility in designing/tailoring/shaping the frequency response of the modulator, as intended by Kissa (para. 005 and 0036).
Regarding claim 25, the Kissa – Manouvrier – Kato combination considers (para. 0007, 0055, 0128, and 0145 of Kato) that the contemplated modulator can further comprise one or more biasing circuits configured for separately biasing at least one of the phase shifters of the phase shifter pairs.
Regarding claim 27, the Kissa – Manouvrier – Kato combination considers (para. 0004, 0005, 0092, and 0156 of Kato) a communication link comprising a transmitter, a receiver, and an optical link between the transmitter and receiver wherein the transmitter comprises the contemplated electro-optic Mach-Zehnder modulator.
Claim 19 is rejected under 35 U.S.C. 103 as being unpatentable over Kissa in view of Manouvrier, and further in view of Tennant (US 2019/0267708 A1).
Regarding claim 19, Kissa considers only fixed optical waveguide crossings (Fig. 1) and does not teach that they can be switchable. However, Tennant teaches (Fig. 6; para. 0100, 0101, and 0111 – 0113) an electrically-switchable optical waveguide crossing 606,608 that has electrically-switchable optical outputs is configured to provide an electrically-switchable optical delay by switching between a direct connection of optical waveguides (input and output waveguide of 606) and a delay element (waveguide loop) between them. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that fixed optical waveguide crossings in Kissa can be modified and become electrically-switchable, in accordance with the teachings of Tennant about electrically-switchable optical delay lines, so that the optical delay and, consequently, the frequency response of the electro-optic modulator can be reconfigurable (by being electrically-switchable).
Claim 24 is rejected under 35 U.S.C. 103 as being unpatentable over Kissa in view of Manouvrier, and further in view of “Velocity-Matching Techniques for Integrated Optic Traveling Wave Switch/Modulators” by Alferness et al, JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-20, NO. 3, pp. 301 – 309, 1984 (hereinafter Alferness).
Regarding claim 24, while Kissa considers, by way of example but not limitation, co-propagating electrical and optical signals, Alferness describes (Figs. 2 – 4; Sections II – V) an electro-optic modulator wherein velocity matching between electrical and optical signals is achieved by 180o phase reversals (the same general principle as that in Kissa). Alferness considers BOTH co-propagating electrical and optical signals (as in Kissa; with d = 1 – N0/Nm < 1) AND counter-propagating electrical and optical signals (with d = 1 + N0/Nm > 1). 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 electro-optic modulator of Kissa can be configured to operate for counter-propagating electrical and optical signals, as a design choice that is described by Alferness and provides the benefit of a narrow modulation band at a high-frequency carrier which is useful for certain practical applications (“we note that the required period can be reduced for a given velocity-match frequency by increasing d. This may be desirable for practical reasons when minimal bandwidth at high frequency is desired. This can be conveniently achieved by using a counter-propagating microwave signal. In this case, d = 1 + N0/Nm” at para. bridging columns on p. 307).
Conclusion
Applicant's arguments filed 7/10/25 have been fully considered but they are not persuasive and have failed to place the instant application in condition for allowance. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any extension fee pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the date of this final action.
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