Contract analysis

I. Executive Summary This memorandum analyzes the viability of asserting infringement under the doctrine of equivalents ("DOE") for three specific patent claims asserted by Optiwave Semiconductor Corp. ("OWS") against Lumicore Technologies, Inc. ("Lumicore") in the above-captioned matter: Claims 3 and 7 of U.S. Patent No. 10,891,193 (the "'193 Patent") and Claim 12 of U.S. Patent No. 11,402,015 (the "'015 Patent"). T

II. Background A. The Asserted Patents and Claims

1. The '193 Patent — U.S. Patent No. 10,891,193. The '193 Patent, titled "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate," was filed on April 7, 2017 and issued on January 12, 2021. The original assignee of record is Optiwave Semiconductor Corp. The '193 Patent claims the benefit of U.S. Provisional Application No. 62/499,117, filed April 7, 2017, which is a common provisional application

2. The '015 Patent — U.S. Patent No. 11,402,015. The '015 Patent, titled "Polarization-Diverse Grating Coupler for Silicon Photonic Transceivers," was filed on August 30, 2019 and issued on August 2, 2022. Like the '193 Patent, the '015 Patent was originally assigned to Optiwave Semiconductor Corp. and claims the benefit of the same U.S. Provisional Application No. 62/499,117, filed April 7, 2017. The '015 Patent was

1. The Function-Way-Result Test (derived from Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608 (1950)): Under this test, an accused element is equivalent to a claim limitation if it performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed element.

2. The Insubstantial Differences Test: Under this alternative formulation, infringement under the doctrine of equivalents is found when the differences between the claim limitation and the accused element are insubstantial. See Warner-Jenkinson, 520 U.S. at 40. This memorandum primarily applies the function-way-result test, as is standard in Eastern District of Texas practice and consistent with Judge Gilstrap's prio

1. The Unforeseeability Exception: The equivalent at issue was unforeseeable at the time of the narrowing amendment. Festo, 535 U.S. at 740–41. If the alleged equivalent was based on technology that did not exist or was not known in the relevant art at the time of the amendment, the patentee could not reasonably have been expected to have claimed it, and the presumption of surrender does not apply.

2. The Tangential Relation Exception: The rationale underlying the narrowing amendment bore only a tangential relation to the equivalent in question. Id. at 740–41. If the reason the applicant narrowed the claim had nothing (or only a peripheral connection) to do with the specific equivalent now at issue, the patentee should not be foreclosed from asserting equivalence with respect to that particular variation.

3. The "Other Reason" Exception: There is some other reason suggesting that the patentee could not reasonably have been expected to have described the insubstantial substitute in question. Id. This exception serves as a catch-all but is narrowly applied by the Federal Circuit. See Festo Corp. v. Fenmore & Co., 344 F.3d 1359, 1369 (Fed. Cir. 2003) (en banc) (on remand). The burden of overcoming the Festo presumption r

III. Analysis of '193 Patent — Claims 3 and 7 A. Claim Language The relevant claims of the '193 Patent are set forth in full in Appendix D. For purposes of this analysis, we reproduce the pertinent claim language below. Claim 1 (independent) recites:

1. An integrated coherent optical transceiver, comprising: a silicon-on-insulator substrate; a transmitter path integrated on the silicon-on-insulator substrate, the transmitter path comprising a laser source optically coupled to a Mach-Zehnder modulator array configured to modulate an optical carrier signal with a data signal; a receiver path integrated on the silicon-on-insulator substrate, the receiver path compri

3. The integrated coherent optical transceiver of claim 1, wherein the receiver path further comprises a coherent detection module disposed between the input waveguide and the signal processing unit, the coherent detection module comprising: an optical hybrid configured to mix the modulated optical signal with a local oscillator signal from the local oscillator source to produce at least four mixed optical signals; a

7. The integrated coherent optical transceiver of claim 5, wherein the coherent detection module is configured to detect both in-phase (I) and quadrature (Q) components of the modulated optical signal by producing at least eight mixed optical signals from the optical hybrid, and wherein the coherent detection module further comprises a polarization beam splitter integrated upstream of the optical hybrid to separate o

1. Function. The claimed "coherent detection module" functions to detect modulated optical signals using coherent detection techniques — specifically, by mixing the incoming modulated optical signal with a local oscillator signal to extract both phase and amplitude information from the received signal. This function is fundamental to coherent optical communication and enables the recovery of complex modulation format

2. Way. The more nuanced question is whether the accused design operates in "substantially the same way" as the claimed coherent detection module. The accused products employ a distributed architecture rather than a unitary module, and the TIA is implemented on a separate electronic die rather than being monolithically integrated on the SOI substrate. Lumicore will argue that these structural differences represent a

3. Result. Both the claimed "coherent detection module" and the accused coherent detection architecture achieve substantially the same result: high-bandwidth coherent detection of modulated optical signals, with recovery of both in-phase and quadrature components of the signal, enabling the demodulation of complex modulation formats on a silicon-integrated photonic platform. The performance specifications of the accu

4. Overall DOE Assessment for '193 Claims 3 and 7. Based on the foregoing function-way-result analysis, we conclude that the accused products — the LumiLink 400G-ZR+, LumiLink 800G-DR8, and LumiEdge 1600G-LR — infringe Claims 3 and 7 of the '193 Patent under the doctrine of equivalents with respect to the "coherent detection module" limitation. The accused distributed coherent detection architecture performs substant

1. The Festo Presumption Applies. As discussed in Section III.B above, the "coherent detection module" limitation in Claims 3 and 7 was narrowed during prosecution by an amendment filed on September 16, 2019 in response to the examiner's § 102 rejection based on Takahashi. The amendment was made expressly to overcome the prior-art rejection — that is, for a reason related to patentability. Under Festo, this triggers

2. Rebuttal Arguments — Festo Exceptions. ##### a. Tangential Relation Exception (Primary Argument) Our primary argument for overcoming the Festo presumption on the '193 Patent claims is the tangential relation exception. Under this exception, the presumption of surrender is rebutted where "the rationale underlying the amendment [bore] no more than a tangential relation to the equivalent in question." Festo, 535 U.S.

3. Overall Estoppel Risk Assessment for '193 Claims 3 and 7. Risk Level: Moderate. The Festo presumption clearly applies because the "coherent detection module" limitation was narrowed during prosecution to overcome a § 102 rejection. The tangential-relation exception is viable and well-supported: the amendment was directed at distinguishing over Takahashi's WDM-based coherent receiver architecture, which is a struct

IV. Analysis of '015 Patent — Claim 12 A. Claim Language The relevant claims of the '015 Patent are set forth in full in Appendix D. Claim 12 is a dependent claim. For purposes of this analysis, we reproduce the pertinent claim language below. Claim 9 (independent, parent claim) recites:

9. A polarization-diverse grating coupler for a silicon photonic transceiver, comprising: a silicon waveguide layer disposed on a buried oxide layer of a silicon-on-insulator substrate; a grating structure patterned in the silicon waveguide layer and configured to receive an optical signal from an optical fiber positioned above the grating structure; a first output waveguide configured to carry a first polarization c

10. The polarization-diverse grating coupler of claim 9, wherein the grating structure comprises a periodic pattern of scattering elements configured to diffract the optical signal into the silicon waveguide layer. Claim 12 (dependent on Claim 10, and through it on Claim 9) recites:

12. The polarization-diverse grating coupler of claim 10, wherein the grating structure comprises a two-dimensional sub-wavelength grating having a first periodic pattern along a first axis and a second periodic pattern along a second axis perpendicular to the first axis, the first periodic pattern having a first period selected to couple the first polarization component, and the second periodic pattern having a seco

1. Function. The claimed "two-dimensional sub-wavelength grating" functions as a polarization-splitting coupling element that simultaneously couples both TE and TM polarization modes from an optical fiber into the silicon photonic integrated circuit, directing the two orthogonal polarization components into separate output waveguides. This dual-function coupling-and-splitting operation is achieved in a single grating