EXPERT REPORT OF DR. CAROLINE ASHFORD, PH.D.

EXPERT REPORT OF DR. CAROLINE ASHFORD, PH.D.
REGARDING THE VALIDITY OF U.S. PATENT NOS. 10,234,847; 10,891,193; 9,678,562; AND 11,402,015
Optiwave Semiconductor Corp. v. Lumicore Technologies, Inc. Case No. 2:24-cv-00319-JRG United States District Court for the Eastern District of Texas
Draft — For Submission June 15, 2025
Prepared by:
Dr. Caroline Ashford, Ph.D. Professor of Electrical Engineering & Photonics Northfield Institute of Technology 2400 Sheridan Road Evanston, Illinois 60208
Prepared for:
Calderwood & Harkness LLP Counsel for Plaintiff Optiwave Semiconductor Corp.
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I. INTRODUCTION AND QUALIFICATIONS
A. Identity and Role
1.  My name is Dr. Caroline Ashford. I am a Professor of Electrical Engineering and Photonics at the Northfield Institute of Technology ("NIT"), located in Evanston, Illinois, where I have held a tenured faculty appointment since 2008. I have been retained by Calderwood & Harkness LLP, through responsible partner Alan Ngo, on behalf of Plaintiff Optiwave Semiconductor Corp. ("OWS"), to serve as a technical expert on validity issues in this matter.
2.  My retention agreement with Calderwood & Harkness LLP is dated August 1, 2024. Pursuant to that agreement, I am compensated at a rate of $950 per hour for all time spent on this engagement, including but not limited to document review, analysis, report preparation, deposition preparation, deposition testimony, and trial testimony. The estimated engagement budget for both infringement and validity opinions is approximately $1.1 million. My compensation is not contingent in any way upon the outcome of this litigation or upon the substance of the opinions I express.
3.  The purpose of this report is to provide my expert opinions rebutting the invalidity contentions asserted by Defendant Lumicore Technologies, Inc. ("Lumicore") regarding U.S. Patent No. 10,234,847 (the "'847 Patent"), U.S. Patent No. 10,891,193 (the "'193 Patent"), U.S. Patent No. 9,678,562 (the "'562 Patent"), and U.S. Patent No. 11,402,015 (the "'015 Patent") (collectively, the "Asserted Patents"). Specifically, I have been asked to analyze the 23 prior-art references cited by Lumicore in its Patent Rule 3-3 Invalidity Contentions served on October 14, 2024, and to opine on whether any of those references, alone or in combination, anticipates or renders obvious any asserted claim of any of the Asserted Patents.
4.  I have also been asked to address Lumicore's prior-conception defense under 35 U.S.C. § 102(g) against the '015 Patent and to evaluate secondary considerations of non-obviousness relevant to all four Asserted Patents. This report sets forth my opinions and the bases therefor in compliance with Federal Rule of Civil Procedure 26(a)(2)(B).
B. Professional Qualifications
5.  I hold a Doctor of Philosophy (Ph.D.) degree in Electrical Engineering with a concentration in Photonic Integrated Circuits from the Massachusetts Institute of Technology, a Master of Science (M.S.) degree in Electrical Engineering from Stanford University, and a Bachelor of Science (B.S.) degree in Physics from the University of Michigan, Ann Arbor.
6.  I have over twenty years of experience in research and development in the field of silicon photonics. My research has spanned a broad range of topics central to this litigation, including waveguide design and optimization, optical transceiver architecture and integration, thermal management of photonic integrated circuits ("PICs"), grating coupler technology, dense wavelength-division multiplexing ("DWDM") systems, coherent optical detection, and high-bandwidth optical communication systems for data-center interconnects.
7.  Throughout my career, I have authored or co-authored over 130 peer-reviewed journal articles and conference papers in the fields of silicon photonics, integrated optics, and optical communication systems. My work has been published in leading venues including IEEE Journal of Lightwave Technology, IEEE Photonics Technology Letters, Optics Express, Optica, Nature Photonics, and the Proceedings of the Optical Fiber Communications Conference (OFC) and the European Conference on Optical Communication (ECOC). I have served on the editorial boards of IEEE Journal of Lightwave Technology (2012–2018) and Optics Express (2016–present), and I have served as a reviewer for numerous additional journals in the field.
8.  I am a named inventor on 14 issued United States patents related to photonic integrated circuit design, covering innovations in waveguide coupling, modulator design, photodetector integration, and thermal management of silicon-photonic devices. These patents have been assigned to NIT and, in certain cases, licensed to commercial entities in the photonics industry.
9.  I have previously served as a testifying expert witness in eight patent cases involving semiconductor and photonics technologies. These engagements have included matters in the United States District Courts for the Northern District of California, the District of Delaware, and the Eastern District of Texas, as well as proceedings before the Patent Trial and Appeal Board of the United States Patent and Trademark Office. In each of these matters, I provided opinions on issues of claim construction, infringement, and/or invalidity. A complete list of my prior expert witness engagements is included in my curriculum vitae, which is attached hereto as Appendix E.
10.  I am a Fellow of the IEEE and a Fellow of the Optical Society of America. I am also a member of SPIE (The International Society for Optics and Photonics) and the American Physical Society. I have received numerous awards and honors for my research contributions, including the IEEE Photonics Society Young Investigator Award (2010), the NIT Distinguished Research Prize (2015), and the Optical Society of America's Joseph Fraunhofer Award/Robert M. Burley Prize (2021).
11.  My full curriculum vitae, including a complete list of publications, patents, prior testimony, and professional activities, is attached as Appendix E to this report.
C. Compensation
12.  As noted above, I am compensated at a rate of $950 per hour for all time spent in connection with this engagement. My compensation is in no way contingent upon the outcome of this litigation, the content of my testimony, or the nature of the opinions I express. I have no financial interest in OWS or in the outcome of this case.
D. Summary of Opinions
13.  Based on my review of the materials identified in Section IV of this report, my education and experience in the field of silicon photonics, and the analysis set forth in detail below, I hold the following opinions to a reasonable degree of scientific and engineering certainty:
(a) Each of the 23 prior-art references cited by Lumicore in its October 14, 2024 P.R. 3-3 Invalidity Contentions fails to anticipate or render obvious any asserted claim of any of the four Asserted Patents — U.S. Patent Nos. 10,234,847; 10,891,193; 9,678,562; and 11,402,015 — whether considered individually or in any combination proposed by Lumicore.
(b) The asserted claims of all four Asserted Patents are valid over the cited prior art, both individually and in every combination identified in Lumicore's invalidity contentions.
(c) Strong secondary considerations of non-obviousness — including substantial commercial success, long-felt but unsolved need, the failure of others to solve the relevant technical problems, deliberate copying by Lumicore, and significant licensing activity — further support the validity of all asserted claims of all four Asserted Patents.
(d) Lumicore's prior-conception defense under 35 U.S.C. § 102(g) against the '015 Patent fails because the internal design documents upon which Lumicore relies are uncorroborated, do not establish a definite and permanent idea of the complete and operative invention as claimed, and are not supported by evidence of diligent reduction to practice.
14.  The bases for each of these opinions are set forth in detail in the remainder of this report.
II. LEGAL STANDARDS APPLIED
15.  I am not a lawyer, and I do not offer legal opinions. However, I have been informed by counsel of the legal standards applicable to patent validity, and I have applied those standards in forming my technical opinions. The legal standards I understand to be applicable are summarized below.
A. Presumption of Validity
16.  I understand that each of the Asserted Patents is presumed valid under 35 U.S.C. § 282. This statutory presumption means that a party challenging the validity of a patent bears the burden of proving invalidity. I further understand that this burden must be met by clear and convincing evidence, which is a heightened standard requiring that the evidence make it highly probable that the patent claims are invalid. I have applied this standard in evaluating Lumicore's invalidity contentions.
17.  I understand that the presumption of validity applies on a claim-by-claim basis and that each asserted claim is independently entitled to the presumption. Accordingly, I have analyzed each asserted claim of each Asserted Patent separately in evaluating Lumicore's prior-art references.
B. Anticipation Under 35 U.S.C. § 102
18.  I understand that a patent claim is anticipated under 35 U.S.C. § 102 only if a single prior-art reference discloses each and every limitation of the claimed invention, arranged or combined in the same way as recited in the claim. Anticipation is a question of fact and requires an exact correspondence between the claim limitations and the disclosures of the prior-art reference. If even a single limitation of a claim is not disclosed by the reference, the reference does not anticipate that claim.
19.  I further understand that, to serve as an anticipatory reference, the prior-art disclosure must be enabling — that is, it must contain sufficient information to enable a person of ordinary skill in the art to make and use the claimed invention without undue experimentation. A reference that merely mentions a concept or describes it at a high level of abstraction, without providing sufficient technical detail to enable its practice, does not anticipate.
20.  I have applied these principles in my analysis of each prior-art reference that Lumicore asserts as anticipating any asserted claim of any of the Asserted Patents.
C. Obviousness Under 35 U.S.C. § 103
21.  I understand that a patent claim is invalid as obvious under 35 U.S.C. § 103 only if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious to a person of ordinary skill in the art at the time of the invention. Obviousness is a question of law based on underlying factual determinations.
22.  I understand that the framework for analyzing obviousness was established by the Supreme Court in Graham v. John Deere Co., 383 U.S. 1 (1966), and requires consideration of four factors: (1) the scope and content of the prior art; (2) the differences between the prior art and the claims at issue; (3) the level of ordinary skill in the pertinent art; and (4) secondary considerations of non-obviousness, such as commercial success, long-felt but unsolved need, failure of others, copying, and other objective indicia.
23.  I understand that, under KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), there must be some articulated reason, suggestion, or motivation to combine prior-art references in the manner proposed, and there must be a reasonable expectation that the combination would succeed. The analysis must guard against the use of impermissible hindsight reconstruction — that is, using the patent itself as a roadmap to select and assemble prior-art references that, taken together, might appear to teach the claimed invention.
24.  I further understand that the analysis of obviousness must consider the claimed invention as a whole, not merely individual limitations in isolation. The question is whether the overall combination of features recited in a claim would have been obvious to a person of ordinary skill in the art, not whether each feature independently existed somewhere in the prior art.
25.  I have applied these principles in my analysis of each combination of prior-art references that Lumicore asserts as rendering any asserted claim of any of the Asserted Patents obvious.
D. Prior Conception Under 35 U.S.C. § 102(g)
26.  I understand that Lumicore has asserted a prior-conception defense under 35 U.S.C. § 102(g) against the '015 Patent. I understand that, to establish prior conception, a party must demonstrate: (1) a definite and permanent idea of the complete and operative invention, as it is subsequently claimed, formed in the mind of the inventor prior to the patentee's date of invention; and (2) corroboration of the conception by evidence beyond the inventor's own testimony, including contemporaneous documentary evidence and/or testimony of independent witnesses.
27.  I further understand that conception without reduction to practice — either actual or constructive (i.e., the filing of a patent application) — is insufficient unless the conceiving party can also demonstrate reasonable diligence toward reduction to practice from a time just prior to the patentee's date of invention to the conceiving party's own date of reduction to practice.
28.  I have applied these principles in my analysis of Lumicore's prior-conception defense against the '015 Patent.
III. PERSON OF ORDINARY SKILL IN THE ART (POSITA)
A. Definition
29.  In forming my opinions, I have considered the perspective of a person of ordinary skill in the art ("POSITA") at the time of each Asserted Patent's relevant filing date. Based on my experience in the field, my review of the technical literature, and my understanding of the level of skill reflected in the Asserted Patents and the cited prior art, I have determined that a POSITA at the time of each patent's filing would have had, at a minimum, the following qualifications:
(a) A Master of Science (M.S.) or Doctor of Philosophy (Ph.D.) degree in electrical engineering, photonics, optical engineering, or a closely related discipline; and
(b) At least three (3) years of hands-on experience in the design, fabrication, or testing of silicon photonic integrated circuits, including familiarity with waveguide structures, optical modulator and photodetector integration, grating coupler design, thermal management techniques applicable to photonic devices, and coherent optical transceiver architectures.
30.  Alternatively, a person with less formal education — such as a Bachelor of Science (B.S.) degree in electrical engineering, physics, or a related field — but with correspondingly greater practical experience in silicon photonic integrated circuit design, fabrication, or testing (e.g., five or more years of direct industry experience) could also qualify as a POSITA. The key requirement is that the individual possess sufficient depth of knowledge and practical experience specific to silicon photonic integrated circuit technology, as opposed to general semiconductor device engineering.
31.  This definition reflects the highly specialized nature of the technology at issue. Silicon photonics is a distinct sub-field within semiconductor engineering that draws upon principles of optics, electromagnetics, materials science, and semiconductor fabrication. While it shares certain foundational knowledge with broader semiconductor engineering, the design challenges and optimization criteria specific to photonic integrated circuits — such as managing optical loss, maintaining polarization control, achieving efficient fiber-to-chip coupling, and addressing the unique thermal sensitivities of photonic elements — require specialized expertise that a general semiconductor engineer would not possess without additional training or experience in photonics.
B. Relevance of POSITA Definition
32.  The POSITA definition I have adopted is consistent with the definition I used in my companion expert report on infringement in this matter, as well as the definition I set forth in my declaration submitted in connection with OWS's Opening Claim Construction Brief on November 15, 2024. It is also consistent with the level of skill reflected in the Asserted Patents' specifications and the cited prior art, both of which assume familiarity with concepts and techniques that are specific to silicon photonic integrated circuit design.
33.  I understand that Lumicore's technical expert, Dr. Rajesh Sundaram of Pacific Western University, San Diego, California, has offered a broader POSITA definition in his declaration submitted in support of Lumicore's Responsive Claim Construction Brief on December 6, 2024. Dr. Sundaram's definition encompasses general semiconductor engineers without photonics-specific experience, which in my opinion improperly lowers the baseline level of ordinary skill in the art. This broader definition would effectively encompass engineers who design electronic integrated circuits (e.g., CMOS logic, memory, analog/mixed-signal devices) but who have no experience with the optical phenomena, waveguide physics, or photonic device design principles that are central to the technologies at issue. Such an engineer, in my experience, would not have the knowledge or skill to understand, let alone design or optimize, the specific photonic integrated circuit features claimed in the Asserted Patents without substantial additional training.
34.  Dr. Sundaram's improperly broad POSITA definition has significant implications for the obviousness analysis. By lowering the level of skill attributed to the hypothetical person of ordinary skill, Dr. Sundaram's definition makes it appear that a wider range of prior-art references would be relevant and combinable, and that the differences between the prior art and the claimed inventions are smaller than they actually are. In reality, the specialized knowledge required to bridge the gap between the cited prior art and the claimed inventions was not within the ordinary skill of a general semiconductor engineer, and the claimed innovations represent non-trivial advances that were not predictable to a POSITA as properly defined.
IV. MATERIALS CONSIDERED
35.  In forming the opinions expressed in this report, I have reviewed and considered the materials identified below. A complete enumerated list of all materials considered is attached as Appendix F.
A. Patent Documents
36.  I have reviewed the complete specifications, claims, and drawings of each of the four Asserted Patents:
(a) U.S. Patent No. 10,234,847 ("the '847 Patent"), entitled "Multi-Channel Silicon Photonic Waveguide Multiplexer with Low Insertion Loss," filed September 14, 2016, issued March 19, 2019;
(b) U.S. Patent No. 10,891,193 ("the '193 Patent"), entitled "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate," filed April 7, 2017, issued January 12, 2021;
(c) U.S. Patent No. 9,678,562 ("the '562 Patent"), entitled "Method for Thermal Management of Photonic Integrated Circuits Using Embedded Micro-Channel Heat Sinks," filed November 22, 2014, issued June 13, 2017; and
(d) U.S. Patent No. 11,402,015 ("the '015 Patent"), entitled "Polarization-Diverse Grating Coupler for Silicon Photonic Transceivers," filed August 30, 2019, issued August 2, 2022.
37.  I have also reviewed the complete prosecution histories for all four Asserted Patents, including all office actions, applicant responses, claim amendments, declarations and affidavits submitted during prosecution, examiner interview summaries, and all papers related to the continuation and provisional-application relationships among the patents. In particular, I have reviewed Provisional Application No. 62/499,117, filed April 7, 2017, which is the parent provisional application to both the '193 Patent and the '015 Patent. I have also reviewed the continuation relationship between the '562 Patent and the '847 Patent, which share a common patent family.
B. Invalidity Contentions and Supporting Materials
38.  I have reviewed Lumicore's P.R. 3-3 Invalidity Contentions, served on October 14, 2024, in their entirety. These contentions cite a total of 23 prior-art references and assert anticipation under 35 U.S.C. § 102, obviousness under 35 U.S.C. § 103, and/or prior conception under 35 U.S.C. § 102(g) against the Asserted Patents. I have reviewed all 23 prior-art references in their entirety, including the full text of each journal article, patent specification, PCT application, conference paper, and internal document cited by Lumicore.
39.  I am informed that Lumicore's technical expert, Dr. Rajesh Sundaram, is expected to submit his expert report on invalidity on or about July 15, 2025. I have not yet received Dr. Sundaram's report but have reviewed the positions taken by Lumicore and Dr. Sundaram in the invalidity contentions and in the claim construction briefing. I reserve the right to supplement this report upon receipt and analysis of Dr. Sundaram's report, as discussed further in Section XII below.
C. Deposition Transcripts
40.  I have reviewed the following deposition transcripts:
(a) Deposition of Dr. Jian-Wei Huang, Chief Technology Officer of OWS, taken November 5, 2024, including all exhibits marked at the deposition;
(b) Deposition of Dr. Sandra Michaud, Chief Technology Officer of Lumicore Technologies, Inc., taken November 19, 2024, including all exhibits marked at the deposition; and
(c) Deposition of Kevin Ng of Benchmark Semiconductor Analysis, LLC, taken January 7, 2025, including all exhibits marked at the deposition.
D. Technical Literature and Industry Standards
41.  I have reviewed a substantial body of technical literature and industry standards relevant to the technologies at issue in this case, including but not limited to: IEEE standards applicable to optical transceiver modules and silicon photonic devices; technical dictionaries and reference works in the fields of photonics and optical engineering; university-level textbooks on silicon photonics, integrated optics, and optical communication systems; and peer-reviewed journal articles and conference papers relating to silicon photonics, waveguide multiplexing, coherent transceiver design, thermal management of photonic integrated circuits, and grating coupler technology. Specific references relied upon are identified throughout this report and listed in Appendix F.
E. Discovery Documents
42.  I have reviewed a substantial volume of discovery documents produced by both parties in this litigation. OWS has produced approximately 182,000 documents comprising approximately 1.4 million pages, and Lumicore has produced approximately 147,000 documents comprising approximately 980,000 pages. While I have not reviewed every individual document in these productions, I have reviewed, with the assistance of counsel, those documents identified as relevant to the validity issues addressed in this report.
43.  Specifically, I have reviewed the following categories of discovery documents:
(a) Lumicore internal design documents dated 2016–2017, cited by Lumicore in support of its prior-conception defense against the '015 Patent, including engineering notebook entries, design presentations, and internal memoranda;
(b) Benchmark Semiconductor Analysis, LLC teardown reports for the LumiLink 400G-ZR+ module (dated December 12, 2022), the LumiLink 800G-DR8 module (dated June 2023), and the LumiEdge 1600G-LR module (dated February 2024);
(c) OWS internal technical documents relating to the development of the patented technologies, including research notebooks, design specifications, simulation results, fabrication records, and testing data; and
(d) Other documents produced by both parties in discovery that counsel identified as relevant to the issues addressed in this report.
F. Other
44.  I have also reviewed the following additional materials:
(a) The Solara Optics, Inc. Asset Purchase Agreement ("APA") dated June 15, 2018, pursuant to which OWS acquired the '562 Patent and eleven other patents from Solara Optics, Inc. for a total consideration of $34.5 million;
(b) The complete claim construction briefing in this matter, including the Joint Claim Construction Statement (October 28, 2024), OWS's Opening Claim Construction Brief (November 15, 2024), Lumicore's Responsive Claim Construction Brief (December 6, 2024), OWS's Reply Claim Construction Brief (December 20, 2024), and the Joint Claim Construction Chart (final version, January 15, 2025);
(c) The Court's scheduling order and all relevant case management orders; and
(d) Other materials as identified in Appendix F.
V. OVERVIEW OF THE ASSERTED PATENTS
45.  This section provides an overview of each of the four Asserted Patents, including their subject matter, filing and issue dates, assignee history, asserted claims, and the key innovations they embody. A thorough understanding of the Asserted Patents is essential to evaluating whether the cited prior art anticipates or renders obvious the asserted claims.
A. The '847 Patent (U.S. Patent No. 10,234,847)
46.  Title: "Multi-Channel Silicon Photonic Waveguide Multiplexer with Low Insertion Loss."
47.  Filing and Issue Dates: The '847 Patent was filed on September 14, 2016, and issued on March 19, 2019.
48.  Assignee: The '847 Patent was originally assigned to Optiwave Semiconductor Corp. and remains assigned to OWS.
49.  Related Applications: The '847 Patent shares a continuation relationship with the '562 Patent. Both patents belong to the same patent family, which traces back to the '562 Patent's November 22, 2014 filing date. This family relationship is significant because it reflects the interconnected nature of OWS's innovations in silicon photonic multiplexer design and thermal management — the '847 Patent builds upon the foundational work in photonic IC fabrication that is also reflected in the '562 Patent's thermal management innovations.
50.  Asserted Claims: OWS asserts Claims 1, 3, 5, 9, and 14 of the '847 Patent against Lumicore.
51.  Summary of the Invention: The '847 Patent discloses and claims a multi-channel waveguide multiplexer architecture on a silicon photonic platform that achieves exceptionally low insertion loss for dense wavelength-division multiplexed (DWDM) optical signals. In conventional silicon photonic multiplexers, insertion loss — the loss of optical signal power as light passes through the multiplexer — is a significant performance bottleneck, particularly as the number of multiplexed channels increases. The '847 Patent addresses this problem through a combination of innovations including specific waveguide geometry optimizations, novel coupling structures that minimize transition losses between waveguide sections, and loss-reduction techniques that collectively enable multi-channel multiplexing with insertion losses significantly below those achievable with prior-art approaches.
52.  The significance of the '847 Patent's innovations can be appreciated in the context of the broader trend toward higher-bandwidth optical interconnects in hyperscale data centers. As data rates have increased from 100 Gbps to 400 Gbps and beyond, the number of wavelength channels that must be multiplexed onto a single fiber has correspondingly increased, placing ever-greater demands on multiplexer performance. The low-insertion-loss multiplexer architecture claimed in the '847 Patent enables the high channel counts and tight channel spacings required by next-generation data-center optical interconnects while maintaining signal integrity and power efficiency.
B. The '193 Patent (U.S. Patent No. 10,891,193)
53.  Title: "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate."
54.  Filing and Issue Dates: The '193 Patent was filed on April 7, 2017, and issued on January 12, 2021.
55.  Assignee: The '193 Patent was originally assigned to Optiwave Semiconductor Corp. and remains assigned to OWS.
56.  Priority: The '193 Patent claims priority through Provisional Application No. 62/499,117, filed April 7, 2017. This provisional application is shared with the '015 Patent.
57.  Asserted Claims: OWS asserts Claims 1, 3, 7, 10, 15, and 18 of the '193 Patent against Lumicore.
58.  Summary of the Invention: The '193 Patent discloses and claims a coherent optical transceiver architecture that is monolithically integrated on a silicon substrate, combining optical modulation, coherent detection, and signal-processing functions on a single photonic integrated circuit for high-bandwidth data-center interconnects. Prior to the innovations claimed in the '193 Patent, coherent optical transceivers for data-center applications typically relied on discrete optical components — separate modulators, photodetectors, and electronic processing chips — that were assembled together in a multi-chip module. This approach introduced inter-chip losses, required complex packaging, and limited the achievable bandwidth density.
59.  The '193 Patent's monolithically integrated approach eliminates inter-chip optical losses, reduces packaging complexity, and enables significantly higher bandwidth density by placing all transceiver functions on a single silicon die. The patent's claims recite a specific transceiver architecture that includes a coherent detection module with particular structural and functional characteristics, as discussed in more detail in Section VIII below. This coherent detection module was narrowed during prosecution to distinguish over the prior art, and it represents a key point of distinction between the claimed invention and the references cited by Lumicore.
C. The '562 Patent (U.S. Patent No. 9,678,562)
60.  Title: "Method for Thermal Management of Photonic Integrated Circuits Using Embedded Micro-Channel Heat Sinks."
61.  Filing and Issue Dates: The '562 Patent was filed on November 22, 2014, and issued on June 13, 2017.
62.  Assignee: The '562 Patent was originally assigned to Solara Optics, Inc. On June 15, 2018, OWS acquired the '562 Patent, along with eleven other patents, from Solara Optics pursuant to an Asset Purchase Agreement for a total consideration of $34.5 million. OWS is the current assignee of the '562 Patent.
63.  Related Applications: The '562 Patent shares a continuation relationship with the '847 Patent, and both patents belong to the same patent family.
64.  Asserted Claims: OWS asserts Claims 1, 4, 6, and 11 of the '562 Patent against Lumicore.
65.  Summary of the Invention: The '562 Patent discloses and claims a method for managing thermal dissipation in photonic integrated circuits through the use of embedded micro-channel heat sinks. Thermal management is a critical challenge in silicon photonic devices because the optical performance of photonic elements — including waveguides, modulators, and ring resonators — is highly sensitive to temperature variations. Even small temperature fluctuations can cause wavelength drift in resonant structures, increased optical loss in waveguides, and degraded modulation performance, all of which can severely impair transceiver operation.
66.  The '562 Patent addresses these challenges by embedding micro-channel heat sinks directly within the photonic integrated circuit structure during the fabrication process, rather than relying on external or surface-mounted cooling solutions. This embedded approach provides more efficient and uniform thermal management, enabling stable optical performance at the high power densities required by advanced silicon photonic transceivers. The patent claims recite specific method steps for fabricating and integrating the micro-channel heat-sink structures within the PIC, as well as specific structural and dimensional parameters for the micro-channels, as discussed in more detail in Section IX below.
D. The '015 Patent (U.S. Patent No. 11,402,015)
67.  Title: "Polarization-Diverse Grating Coupler for Silicon Photonic Transceivers."
68.  Filing and Issue Dates: The '015 Patent was filed on August 30, 2019, and issued on August 2, 2022.
69.  Assignee: The '015 Patent was originally assigned to Optiwave Semiconductor Corp. and remains assigned to OWS.
70.  Priority: The '015 Patent claims priority through Provisional Application No. 62/499,117, filed April 7, 2017. This provisional application is shared with the '193 Patent.
71.  Asserted Claims: OWS asserts Claims 1, 5, 8, 12, and 16 of the '015 Patent against Lumicore.
72.  Summary of the Invention: The '015 Patent discloses and claims a polarization-diverse grating coupler design for silicon photonic transceivers that efficiently couples light of two orthogonal polarization states — specifically the transverse-electric (TE) and transverse-magnetic (TM) modes — into and out of silicon waveguides. Efficient fiber-to-chip coupling is a persistent challenge in silicon photonics because of the large mode-field mismatch between standard optical fibers and sub-micron silicon waveguides, and because standard single-mode fibers carry light in an arbitrary, time-varying polarization state that must be properly handled by the on-chip photonic circuit.
73.  Prior to the innovations claimed in the '015 Patent, grating couplers for silicon photonic transceivers typically handled only a single polarization state efficiently, resulting in significant polarization-dependent loss (PDL). Alternatively, some approaches used separate grating couplers for each polarization state, doubling the chip area required for the fiber-coupling interface. The '015 Patent's polarization-diverse grating coupler design overcomes these limitations by efficiently coupling both TE and TM polarization states through a single grating structure, reducing chip area while maintaining low insertion loss and low PDL. Claim 12, in particular, includes a "two-dimensional sub-wavelength grating" limitation that was added during prosecution to overcome a § 103 rejection, and which represents a key structural innovation not found in the prior art.
E. Maintenance and Status
74.  I have been informed by counsel that all four Asserted Patents have been maintained with all required maintenance fees paid and current. All four patents remain in force.
75.  I have further been informed that no inter partes review ("IPR") petitions have been filed against any of the four Asserted Patents to date, although Lumicore has reserved the right to file such petitions. The one-year time bar under 35 U.S.C. § 315(b) — running from the date Lumicore was served with the complaint in this action — is on or about May 1, 2025. As of the date of this draft report, the time-bar date has not yet passed.
VI. LUMICORE'S INVALIDITY CONTENTIONS — OVERVIEW
A. Summary of Lumicore's Contentions
76.  Lumicore served its P.R. 3-3 Invalidity Contentions on October 14, 2024. In those contentions, Lumicore cites a total of 23 prior-art references and asserts that the asserted claims of each of the four Asserted Patents are invalid on the grounds of anticipation under 35 U.S.C. § 102, obviousness under 35 U.S.C. § 103, or both.
77.  Additionally, with respect to the '015 Patent specifically, Lumicore asserts a prior-conception defense under 35 U.S.C. § 102(g), relying on internal design documents purportedly dated 2016–2017 that Lumicore contends demonstrate that its engineers independently conceived of the polarization-diverse grating coupler invention prior to OWS's earliest priority date for the '015 Patent.
78.  For the reasons set forth in detail in Sections VII through X of this report, none of Lumicore's invalidity contentions has merit, and all asserted claims of all four Asserted Patents are valid.
B. Categorization of the 23 Prior-Art References
79.  The following table organizes the 23 prior-art references cited by Lumicore by reference number, type, date, and the Asserted Patent(s) against which each is asserted, together with the specific invalidity theory (anticipation, obviousness, or prior conception). Five key references are identified for detailed analysis in Sections VII through X, and the remaining 18 references are listed by reference number, title, type, date, and target patent with a brief characterization.
80.  In the sections that follow, I address each of these references in detail as applied to the Asserted Patent(s) against which they are cited. For the five key references identified above (Refs. 1–5), I provide an extended analysis. For the remaining 18 references (Refs. 6–23), I provide a systematic analysis that identifies the reference, its subject matter, the specific claim limitations it fails to disclose, and my opinion regarding anticipation and/or obviousness.
VII. ANALYSIS OF PRIOR ART ASSERTED AGAINST THE '847 PATENT (U.S. 10,234,847)
A. Overview of Asserted Claims and Key Limitations
81.  OWS asserts Claims 1, 3, 5, 9, and 14 of the '847 Patent in this litigation. Lumicore's Invalidity Contentions cite six prior-art references against the '847 Patent: Ref. 1 (Takahashi), Ref. 3 (Simonsen), Ref. 6 (Yamamoto), Ref. 7 (Khatri), Ref. 8 (Patel), and Ref. 9 (Andersen).
82.  Independent Claim 1 of the '847 Patent recites a multi-channel waveguide multiplexer on a silicon photonic substrate with specific geometric and performance parameters for achieving low insertion loss. The claim recites, among other limitations, a particular waveguide geometry including specified width, height, and spacing dimensions for the waveguide channels; coupling structures positioned at defined locations along the optical path; and a multi-channel architecture that combines multiple optical signals of different wavelengths onto a single output waveguide.
83.  A key disputed claim term in the '847 Patent is "waveguide multiplexer." OWS proposes that this term should be construed as "an optical device that combines multiple optical signals of different wavelengths onto a single waveguide." Lumicore proposes a narrower construction: "an arrayed waveguide grating that combines optical signals using a slab coupler and phase-shifted waveguide array." The dispute over this term is significant because Lumicore's proposed construction would limit the claim to a specific type of multiplexer architecture (an arrayed waveguide grating or "AWG"), whereas OWS's proposed construction is broader and encompasses the full scope of the disclosed and claimed invention, which is not limited to AWG-type multiplexers. As I explain below, the prior art fails to anticipate or render obvious the asserted claims under either proposed construction.
84.  Dependent Claims 3 and 5 add further structural specificity to the multiplexer architecture claimed in Claim 1. Claim 3 recites additional structural features relating to specific coupling structures that minimize optical transition losses between waveguide sections. Claim 5 recites particular loss-reduction techniques including specific structural modifications to the waveguide geometry that reduce scattering loss and mode-mismatch loss at interfaces within the multiplexer.
85.  Claim 9 contains a limitation that may be construed as a means-plus-function limitation under 35 U.S.C. § 112(f), as discussed further in Section VII.F below.
86.  Claim 14 recites specific insertion-loss thresholds for the multi-channel waveguide multiplexer, requiring that the multiplexer achieve insertion loss below specified values per channel across a defined wavelength range. These quantitative performance requirements are not met by any of the cited prior-art references.
B. Takahashi et al. (Ref. 1, March 2014) — Alleged Anticipation Under § 102
1. Description of the Reference
87.  Takahashi et al., "Dense WDM Silicon Photonic MUX," was published in IEEE Photonics Technology Letters in March 2014. The Takahashi reference describes a silicon-based wavelength-division multiplexer (WDM MUX) employing arrayed waveguide grating (AWG) technology for dense wavelength-division multiplexing applications. Specifically, Takahashi discloses a 16-channel AWG fabricated on a silicon-on-insulator (SOI) platform with 200 GHz channel spacing. The reference reports measured insertion-loss values and channel-to-channel uniformity for the fabricated AWG device.
88.  Takahashi's AWG design utilizes a conventional architecture consisting of input waveguides, a first slab coupler (free propagation region), an array of phase-shifted waveguides, a second slab coupler, and output waveguides. The reference discusses fabrication using standard CMOS-compatible processes on an SOI wafer and presents experimental results characterizing the device's spectral response and insertion loss.
2. Claim-by-Claim Analysis: Missing Limitations
89.  I have conducted a detailed element-by-element comparison of the Takahashi reference against each limitation of Claims 1, 3, 5, 9, and 14 of the '847 Patent. The results of this comparison are set forth in the detailed claim charts attached as Appendix A. My analysis demonstrates that Takahashi fails to disclose several critical limitations of each asserted claim.
90.  Claim 1: Takahashi does not disclose the specific waveguide geometry parameters recited in Claim 1 of the '847 Patent. In particular, Claim 1 requires waveguide channels having specific width and height dimensions that are designed to optimize the fundamental optical mode profile for low-loss propagation and coupling. Takahashi's AWG utilizes waveguide dimensions that differ from those recited in Claim 1, and Takahashi does not disclose or suggest the particular dimensional ranges specified in the claim. Furthermore, Claim 1 recites specific coupling structures positioned at defined locations along the optical path to minimize transition losses between waveguide sections. Takahashi's conventional AWG architecture relies on slab couplers (free propagation regions) for coupling between the input/output waveguides and the phase-shifted array, but does not disclose the specific coupling structures recited in Claim 1, which are structurally and functionally distinct from slab couplers.
91.  Additionally, the multi-channel architecture recited in Claim 1 encompasses a broader class of waveguide multiplexer designs than the specific AWG configuration disclosed in Takahashi. Under OWS's proposed construction of "waveguide multiplexer," Claim 1 is not limited to AWG-type multiplexers, and Takahashi's AWG-specific disclosure does not map onto all of the structural limitations recited in the claim. Even under Lumicore's narrower proposed construction — which limits "waveguide multiplexer" to "an arrayed waveguide grating that combines optical signals using a slab coupler and phase-shifted waveguide array" — Takahashi's design differs in critical respects from the claimed invention. Specifically, the coupling architecture disclosed in Takahashi utilizes a conventional star-coupler geometry that does not incorporate the specific structural features recited in Claim 1 for minimizing coupling losses. The phase-shift distribution in Takahashi's waveguide array differs from the distribution specified in the '847 Patent, which is optimized to reduce phase errors and improve channel uniformity at the low-loss levels claimed. And the insertion-loss performance reported by Takahashi significantly exceeds (i.e., is worse than) the loss thresholds recited in Claim 14.
92.  Claim 3: In addition to failing to disclose all limitations of Claim 1 (from which Claim 3 depends), Takahashi does not disclose the specific coupling structures recited in Claim 3 that are designed to minimize optical transition losses. Claim 3 recites a particular type of mode-matching structure positioned at the interface between different waveguide sections within the multiplexer. Takahashi's AWG does not include such structures and instead relies on conventional adiabatic tapers at the waveguide-to-slab coupler transitions, which do not achieve the same degree of loss reduction and do not correspond to the specific structural features recited in Claim 3.
93.  Claim 5: Takahashi likewise does not disclose the particular loss-reduction techniques recited in Claim 5, which include specific structural modifications to the waveguide geometry that reduce sidewall-scattering loss and mode-mismatch loss at interfaces within the multiplexer. Takahashi's AWG uses standard rib waveguides without the specific geometric modifications recited in Claim 5, and the reference does not suggest or disclose any such modifications.
94.  Claim 9: Takahashi does not disclose the functional limitation recited in Claim 9, whether construed as a means-plus-function limitation (as discussed in Section VII.F) or under its plain meaning. The specific structure corresponding to this limitation, as identified in the '847 Patent specification, is not present in Takahashi's AWG design.
95.  Claim 14: Takahashi reports insertion-loss measurements for its 16-channel AWG device that significantly exceed the low insertion-loss thresholds recited in Claim 14. Specifically, Takahashi reports per-channel insertion losses in the range of approximately 3.5 dB to 5.2 dB across the 16 channels, whereas Claim 14 requires insertion loss below a significantly lower threshold. Takahashi thus fails to disclose the quantitative performance limitation of Claim 14.
3. Opinion.  
96.  For the foregoing reasons, it is my opinion that Takahashi et al. does not anticipate any asserted claim of the '847 Patent. Takahashi fails to disclose each and every limitation of Claims 1, 3, 5, 9, and 14, and therefore cannot constitute an anticipatory reference under 35 U.S.C. § 102 with respect to any of these claims. This conclusion holds under both OWS's and Lumicore's proposed constructions of the disputed claim terms.
C. PCT/EP2015/071234 (Simonsen, Ref. 3) — Alleged Obviousness Under § 103
1. Description of the Reference
97.  Simonsen, PCT Application No. PCT/EP2015/071234, was filed on September 17, 2015, and published under the Patent Cooperation Treaty. The Simonsen reference describes a silicon photonic multiplexer with certain waveguide configurations, including specific waveguide width and height dimensions, and discloses the use of tapered coupling regions at transitions between different waveguide sections. The Simonsen multiplexer is designed for coarse wavelength-division multiplexing (CWDM) applications with four channels at 20 nm channel spacing, a substantially different application than the dense WDM multiplexer addressed by the '847 Patent.
98.  Simonsen's multiplexer architecture differs from the architecture claimed in the '847 Patent in several important respects. First, Simonsen employs a cascaded Mach-Zehnder interferometer (MZI) structure rather than the multi-channel waveguide multiplexer architecture recited in the asserted claims. Second, while Simonsen discloses certain waveguide dimensions, these dimensions are optimized for the lower channel count and wider channel spacing of CWDM applications, not for the dense, multi-channel multiplexing recited in the claims. Third, Simonsen does not disclose the specific coupling structures or loss-reduction techniques recited in dependent Claims 3 and 5, nor does it achieve the insertion-loss performance required by Claim 14.
2. Analysis in Combination with Other References
99.  Lumicore asserts Simonsen in combination with Takahashi and/or other prior-art references (including Refs. 6, 7, 8, and 9) as rendering the asserted claims of the '847 Patent obvious under § 103. Specifically, Lumicore contends that Takahashi provides the basic AWG multiplexer architecture and Simonsen contributes the specific waveguide geometry and coupling configurations that Takahashi lacks.
100.  I have carefully analyzed these proposed combinations and conclude that they do not render any asserted claim of the '847 Patent obvious for several reasons.
101.  Lack of Motivation to Combine: A POSITA at the time of the '847 Patent's filing would not have been motivated to combine Simonsen's CWDM-oriented cascaded MZI multiplexer design with Takahashi's DWDM AWG architecture. These are fundamentally different multiplexer architectures designed for different applications with different performance requirements. Simonsen's cascaded MZI approach is suitable for coarse multiplexing of a small number of widely spaced channels, whereas Takahashi's AWG architecture is designed for dense multiplexing of many closely spaced channels. A POSITA would have recognized that the waveguide dimensions and coupling configurations optimized for Simonsen's CWDM MZI design would not be directly applicable to Takahashi's DWDM AWG architecture without substantial redesign and re-optimization, and that the mere transplantation of Simonsen's waveguide parameters into Takahashi's AWG would not be expected to yield the low insertion-loss performance claimed in the '847 Patent.
102.  Teaching Away: Simonsen expressly teaches that its waveguide configurations are optimized for a CWDM application and states that the disclosed tapered coupling regions are designed for the specific mode-field profiles associated with its four-channel MZI structure. A POSITA reading Simonsen would understand that these configurations are tailored to the particular requirements of a CWDM MZI multiplexer and would not be motivated to apply them in the context of a fundamentally different DWDM AWG architecture. Moreover, Takahashi's own disclosure suggests a different approach to waveguide optimization — specifically, Takahashi teaches the use of deeply etched rib waveguides with particular aspect ratios that differ from Simonsen's shallow-etched channel waveguides. A POSITA would recognize that combining these incompatible waveguide geometries would be contrary to the teachings of both references.
103.  No Reasonable Expectation of Success: Even if a POSITA were motivated to attempt the combination proposed by Lumicore, there would be no reasonable expectation that the combination would succeed in achieving the low insertion-loss performance claimed in the '847 Patent. The insertion-loss performance of a multi-channel waveguide multiplexer depends on a complex interplay of waveguide geometry, coupling architecture, phase-error management, fabrication tolerances, and other factors. Simply combining the waveguide dimensions from one reference with the multiplexer architecture from another, without the specific innovations disclosed in the '847 Patent, would not be expected to achieve the claimed performance levels. The technical literature at the time of filing — including publications by my research group and others — recognized the difficulty of achieving low insertion loss in dense multi-channel silicon photonic multiplexers and characterized it as a significant unsolved challenge.
104.  Remaining Missing Limitations: Even assuming, for the sake of argument, that a POSITA would have been motivated to combine Simonsen with Takahashi, the combination still fails to disclose all limitations of the asserted claims. Specifically, neither Simonsen nor Takahashi (nor their combination) discloses the specific coupling structures recited in Claim 3, the specific loss-reduction techniques recited in Claim 5, the functional limitation of Claim 9, or the quantitative insertion-loss thresholds of Claim 14. These limitations represent the core innovations of the '847 Patent and are not found in any of the cited prior-art references.
3. Opinion.  
105.  For the foregoing reasons, it is my opinion that the combination of Simonsen with Takahashi and/or other cited references does not render any asserted claim of the '847 Patent obvious under 35 U.S.C. § 103. The proposed combination lacks a proper motivation to combine, teaches away from the claimed invention, does not provide a reasonable expectation of success, and in any event fails to disclose all limitations of the asserted claims.
D. Remaining References Asserted Against the '847 Patent
106.  In addition to Takahashi (Ref. 1) and Simonsen (Ref. 3), Lumicore cites four additional references against the '847 Patent: Yamamoto (Ref. 6), Khatri (Ref. 7), Patel (Ref. 8), and Andersen (Ref. 9). I address each of these references below.
1. Yamamoto et al. (Ref. 6) — "AWG-Based Channel Routing in SiPh," J. Lightwave Technology, June 2013
107.  Yamamoto describes an AWG-based channel-routing architecture on a silicon photonic platform, primarily aimed at reconfigurable optical add-drop multiplexer (ROADM) applications in telecommunications networks. While Yamamoto discloses an AWG structure on a silicon substrate, the reference is directed to a fundamentally different application (telecommunications ROADM) than the data-center interconnect application addressed by the '847 Patent, and the AWG design disclosed by Yamamoto is optimized for different performance metrics (e.g., channel isolation and reconfigurability) rather than the low insertion loss that is the focus of the '847 Patent.
108.  My element-by-element comparison of Yamamoto against the asserted claims (set forth in the claim charts in Appendix A) demonstrates that Yamamoto fails to disclose several critical limitations, including the specific waveguide geometry parameters of Claim 1, the coupling structures of Claims 1 and 3, the loss-reduction techniques of Claim 5, and the insertion-loss thresholds of Claim 14. Furthermore, Yamamoto does not disclose or suggest the specific structural features that correspond to the potentially means-plus-function limitation of Claim 9.
109.  Lumicore asserts Yamamoto in combination with Takahashi and/or Simonsen, but the proposed combination suffers from the same deficiencies identified above: lack of motivation to combine references directed to different applications and architectures, no reasonable expectation that the combination would achieve the claimed performance, and continued failure to disclose all claim limitations even in combination.
110.  It is my opinion that Yamamoto, alone or in combination with other cited references, does not anticipate or render obvious any asserted claim of the '847 Patent.
2. U.S. Patent No. 9,104,033 (Khatri, Ref. 7) — Issued August 11, 2015
111.  The Khatri patent describes a silicon photonic multiplexer structure with specific waveguide routing configurations for WDM applications. Khatri discloses a ring-resonator-based multiplexer architecture, which is structurally distinct from the waveguide multiplexer architecture claimed in the '847 Patent. Ring-resonator-based multiplexers operate on fundamentally different physical principles than the architecture disclosed in the '847 Patent, relying on resonant coupling between bus waveguides and ring cavities to achieve wavelength selectivity, rather than the interference-based approach employed by the claimed waveguide multiplexer.
112.  Khatri fails to disclose, among other limitations, the specific waveguide geometry and coupling structures recited in Claim 1, the loss-reduction techniques of Claim 5, and the insertion-loss thresholds of Claim 14. Khatri's ring-resonator architecture inherently exhibits different loss characteristics than the claimed waveguide multiplexer, and the design parameters and optimization approaches are not transferable between the two architectures.
113.  Lumicore's proposed combinations involving Khatri are similarly deficient. A POSITA would not have been motivated to combine a ring-resonator-based multiplexer design with the AWG or other waveguide-multiplexer architectures disclosed in the other cited references, as these are distinct and incompatible design approaches. It is my opinion that Khatri, alone or in combination, does not anticipate or render obvious any asserted claim of the '847 Patent.
3. Patel et al. (Ref. 8) — "Low-Loss Silicon MUX Design," ECOC 2015, September 2015
114.  Patel describes a silicon multiplexer design presented at the 2015 European Conference on Optical Communication. The reference discusses design considerations for reducing insertion loss in silicon photonic multiplexers and presents simulation results for a proposed echelle-grating-based multiplexer. While Patel addresses the same general problem space as the '847 Patent — low-loss multiplexing in silicon photonics — the specific design approach disclosed by Patel (an echelle-grating multiplexer) is structurally distinct from the waveguide multiplexer architecture claimed in the '847 Patent.
115.  Patel's echelle-grating design utilizes a reflective diffraction grating integrated on a silicon photonic chip, with waveguide inputs and outputs arranged in a Rowland circle configuration. This architecture differs fundamentally from the waveguide multiplexer of the '847 Patent in its coupling architecture, waveguide layout, and loss mechanisms. Patel fails to disclose the specific waveguide geometry, coupling structures, and loss-reduction techniques recited in the asserted claims, and the insertion-loss values reported in Patel's simulations do not meet the thresholds of Claim 14.
116.  Moreover, Patel's reference is a conference paper presenting preliminary simulation results without experimental validation, and the described design was never fabricated or tested. A POSITA would have recognized that simulation results for an echelle-grating multiplexer cannot be directly translated to performance expectations for the different multiplexer architecture claimed in the '847 Patent.
117.  It is my opinion that Patel, alone or in combination with other cited references, does not anticipate or render obvious any asserted claim of the '847 Patent.
4. PCT/US2014/058722 (Andersen, Ref. 9) — Filed October 1, 2014
118.  The Andersen PCT application describes a reconfigurable optical multiplexer/demultiplexer for silicon photonic applications. Andersen discloses the use of thermally tunable microring resonators to achieve wavelength selectivity, combined with waveguide routing structures for signal distribution. Like Khatri, Andersen's ring-resonator-based approach is fundamentally distinct from the waveguide multiplexer architecture claimed in the '847 Patent.
119.  Andersen fails to disclose the specific waveguide geometry parameters, coupling structures, and loss-reduction techniques recited in the asserted claims. Furthermore, Andersen's thermally tunable microring approach introduces additional insertion loss due to the ring coupling mechanism and thermal tuning elements, and the reference does not disclose performance levels approaching the insertion-loss thresholds of Claim 14.
120.  Lumicore's proposed combinations involving Andersen suffer from the same deficiencies identified with respect to Khatri: there is no motivation to combine a ring-resonator-based design with the other cited references, and the combination in any event fails to disclose all limitations of the asserted claims. It is my opinion that Andersen, alone or in combination, does not anticipate or render obvious any asserted claim of the '847 Patent.
E. Claim Differentiation Analysis
121.  I am aware that Lumicore has argued, in its invalidity contentions and in the claim construction briefing, that independent Claim 1 of the '847 Patent should be construed narrowly in light of the additional limitations recited in dependent Claims 3 and 5. Specifically, Lumicore contends that because Claims 3 and 5 add specific coupling structures and loss-reduction techniques, respectively, Claim 1 should be read as not requiring any particular coupling structure or loss-reduction feature beyond what is expressly recited in Claim 1's own language.
122.  I understand from counsel that this argument is addressed in the claim construction briefing and that OWS has invoked the doctrine of claim differentiation, which supports giving Claim 1 broader scope than its dependents. The claim-differentiation doctrine