REBUTTAL EXPERT REPORT OUTLINE
DR. CAROLINE ASHFORD
Rebuttal to Expert Validity Opinions of Dr. Rajesh Sundaram
ATTORNEY WORK PRODUCT — PRIVILEGED AND CONFIDENTIAL
This memorandum is protected by the attorney-client privilege and work-product doctrine. It is intended solely for use by attorneys and authorized personnel at Calderwood & Harkness LLP in connection with the representation of Optiwave Semiconductor Corp. Dissemination, distribution, or copying of this memorandum to any person not authorized to receive it is strictly prohibited. Nothing in this memorandum constitutes legal advice to any third party or a final opinion of law.
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I. PURPOSE AND SCOPE OF THIS OUTLINE
This internal memorandum outlines the anticipated scope and structure of Dr. Caroline Ashford's rebuttal expert report responding to the validity opinions set forth by Lumicore Technologies, Inc.'s ("Lumicore") technical and validity expert, Dr. Rajesh Sundaram, in his opening expert report. Dr. Sundaram's opening report was served on or about July 15, 2025, or is otherwise anticipated based on Lumicore's invalidity contentions served on October 14, 2024 pursuant to Patent Rule 3-3 of the Local Patent Rules for the Eastern District of Texas. Because this outline was prepared in advance of receiving Dr. Sundaram's opening report, certain sections contain anticipatory analysis based on the invalidity contentions already served and Lumicore's litigation positions to date. The outline will be updated and refined once Dr. Sundaram's final opening report is in hand.
The rebuttal report is due on or about July 15, 2025, which is the defendant's rebuttal expert reports due date as established by the August 12, 2024 Scheduling Order entered by the Court. The Court's scheduling framework provides that plaintiff's opening expert reports were due on June 15, 2025, and plaintiff's rebuttal to defendant's validity case falls on the same July 15, 2025 rebuttal deadline. Accordingly, Dr. Ashford's rebuttal report must be completed, reviewed, finalized, and served on opposing counsel at Hawthorne Vega & Cruz LLP no later than that date. Any failure to meet this deadline would result in the exclusion of Dr. Ashford's rebuttal opinions, which would be devastating to OWS's validity positions.
This outline is keyed to each of the twenty-three (23) prior-art references cited in Lumicore's October 14, 2024 Patent Rule 3-3 Invalidity Contentions and to each invalidity theory advanced therein, including anticipation under 35 U.S.C. § 102, obviousness under 35 U.S.C. § 103, and Lumicore's prior-conception defense as to the '015 Patent. These invalidity theories span the full range of defenses available to Lumicore and present both reference-specific and patent-wide challenges that must be addressed comprehensively in the rebuttal report.
The outline is organized by asserted patent, as follows:
(A) U.S. Patent No. 10,234,847 ("the '847 Patent");
(B) U.S. Patent No. 10,891,193 ("the '193 Patent");
(C) U.S. Patent No. 9,678,562 ("the '562 Patent"); and
(D) U.S. Patent No. 11,402,015 ("the '015 Patent").
Cross-references to Calderwood & Harkness LLP's internal invalidity contentions analyses are noted throughout this memorandum. These include the analyses dated November 1, 2024 (for the '847 Patent), November 3, 2024 (for the '193 Patent), November 5, 2024 (for the '562 Patent), and November 7, 2024 (for the '015 Patent), as well as the prosecution history review memoranda prepared in September 2024 and the secondary considerations memorandum dated December 2024. These internal work-product documents form the analytical foundation upon which Dr. Ashford's rebuttal opinions will be constructed and should be provided to her for review in conjunction with the preparation of the rebuttal report.
This memorandum is intended to serve as a comprehensive roadmap for the drafting team, including Dr. Ashford herself, and to ensure that no invalidity theory or prior-art reference is overlooked. Given the complexity of the matter — four asserted patents, twenty-three prior-art references, multiple invalidity theories, and a prior-conception defense — careful coordination among all team members will be essential to producing a thorough, accurate, and litigation-ready rebuttal expert report.
II. QUALIFICATIONS AND POSITA DEFINITION
A. Dr. Ashford's Qualifications for Rebuttal Testimony
Dr. Caroline Ashford is eminently qualified to serve as a rebuttal expert witness on the validity of the four asserted patents in this litigation. Dr. Ashford is currently a tenured Professor of Electrical Engineering and Photonics at the Northfield Institute of Technology (NIT) in Evanston, Illinois, where she has held a faculty appointment since 2006. She holds a Bachelor of Science degree in Physics from Stanford University (1998), a Master of Science degree in Electrical Engineering from the Massachusetts Institute of Technology (2000), and a Doctor of Philosophy in Electrical Engineering and Applied Physics from the California Institute of Technology (2004). Her doctoral dissertation focused on the design and fabrication of silicon photonic waveguides for wavelength-division multiplexing applications, which is directly relevant to the technology at issue in this case.
Dr. Ashford brings over twenty years of combined research and industry experience in the fields of silicon photonics, waveguide design, integrated optical transceivers, and photonic integrated circuit (PIC) thermal management. Prior to joining NIT, she worked as a Senior Design Engineer at Cascade Group from 2004 to 2006, where she contributed to the development of next-generation optical fiber and waveguide coupling technologies. Her industry experience provides her with practical insight into the design challenges faced by engineers in the silicon photonics field, which is directly relevant to the obviousness analysis in this matter.
Dr. Ashford is the author or co-author of more than one hundred (100) peer-reviewed publications in leading journals, including Nature Photonics, IEEE Photonics Technology Letters, Optics Express, Journal of Lightwave Technology, and IEEE Journal of Quantum Electronics. Her publications span the full range of technologies implicated by the asserted patents, including waveguide multiplexer design, coherent optical transceiver architecture, photonic integrated circuit thermal management, and grating coupler optimization. She is a named inventor on fourteen (14) issued United States patents, several of which relate to silicon photonic waveguide design and photonic integrated circuit packaging.
Dr. Ashford has previously been retained as an expert witness in seven (7) patent cases involving photonic and semiconductor technologies in federal district courts across the country, including cases in the Eastern District of Texas, the District of Delaware, the Central District of California, and the Northern District of California, as well as in proceedings before the Patent Trial and Appeal Board (PTAB) of the United States Patent and Trademark Office. In each of these prior engagements, her testimony was admitted without challenge under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), and its progeny. Her full curriculum vitae and publication list will be attached as Exhibit 1 to the rebuttal report.
Dr. Ashford is a Fellow of the Optical Society of America (OSA), a Senior Member of the Institute of Electrical and Electronics Engineers (IEEE), and a member of the International Society for Optics and Photonics (SPIE). She currently serves on the editorial boards of Journal of Lightwave Technology and Photonics Research and has served as a reviewer for numerous additional journals. She has been invited to give keynote addresses at the Optical Fiber Communication Conference (OFC), the European Conference on Optical Communication (ECOC), and the IEEE Photonics Conference on multiple occasions.
Based on her education, research, industry experience, publication record, and prior expert witness engagements, Dr. Ashford is qualified to opine on all technical issues relevant to the validity of the four asserted patents, including the scope and content of the prior art, the differences between the prior art and the claimed inventions, the level of ordinary skill in the art, the motivation (or lack thereof) to combine prior-art references, and the existence and significance of secondary considerations of non-obviousness.
B. Rebuttal of Dr. Sundaram's POSITA Definition
A critical preliminary issue for the rebuttal report is Dr. Sundaram's definition of a person of ordinary skill in the art ("POSITA"). The POSITA definition directly affects the obviousness analysis under 35 U.S.C. § 103, because it establishes the baseline level of knowledge and skill against which the claimed inventions are measured. If the POSITA is defined too broadly — with an artificially elevated skill level — obviousness combinations that would otherwise be non-obvious may appear trivially obvious. Conversely, if the POSITA is defined too narrowly, anticipation arguments may be artificially strengthened because even general prior-art disclosures may appear to be fully enabling.
Dr. Ashford's POSITA definition, as set forth in her opening claim-construction declaration filed on November 15, 2024, defines a person of ordinary skill in the art at the time of the inventions as a person possessing a Master of Science (M.S.) or Doctor of Philosophy (Ph.D.) degree in electrical engineering, photonics, optical engineering, or a closely related field, together with at least three (3) years of professional or research experience in silicon-photonic integrated circuit design, including experience with waveguide design, optical modulator and detector integration, and/or photonic packaging. This definition reflects the actual level of skill possessed by practicing engineers and researchers in the silicon photonics industry during the relevant time periods (2014–2019), as evidenced by the educational backgrounds and experience levels of individuals working at companies such as OWS, Lumicore, Penmark Industries, Sundial Corporation, and Ashbury & Co., among others.
Dr. Sundaram's opening report is anticipated to define the POSITA either more narrowly or more broadly than is appropriate, in a manner calculated to skew the invalidity analysis in Lumicore's favor. Based on Lumicore's invalidity contentions and Dr. Sundaram's prior publications and expert testimony in other matters, we anticipate that Dr. Sundaram may attempt to inflate the POSITA's skill level — for example, by defining the POSITA as having a Ph.D. and five or more years of specialized experience — in order to make proposed combinations of prior-art references appear more obvious by attributing greater knowledge and combinatory skill to the hypothetical POSITA. Alternatively, Dr. Sundaram may attempt to deflate the POSITA's skill level in certain respects, such as by expanding the relevant field to include general semiconductor fabrication engineering rather than silicon photonics specifically, in order to bring additional, more remote prior-art references within the POSITA's purview for anticipation purposes.
Dr. Ashford's rebuttal report should directly address any deviation by Dr. Sundaram from the POSITA definition she has previously articulated. Specifically, the rebuttal should:
(1) Restate Dr. Ashford's POSITA definition and the factual basis for it;
(2) Identify the specific ways in which Dr. Sundaram's POSITA definition deviates from Dr. Ashford's definition;
(3) Explain why Dr. Sundaram's definition is incorrect, unsupported by the record, or calculated to distort the invalidity analysis;
(4) Demonstrate the impact of the correct POSITA definition on the obviousness analysis for each asserted patent; and
(5) Note that Dr. Ashford's supplemental declaration, filed on December 20, 2024, already responded to Dr. Sundaram's POSITA characterization as presented in Lumicore's responsive claim construction brief, and the rebuttal report should build on the foundation established in that declaration.
The POSITA definition section of the rebuttal report should be positioned early in the report so that it provides the analytical framework for the patent-specific rebuttal sections that follow.
III. GENERAL FRAMEWORK FOR REBUTTAL
A. Burden of Proof
The rebuttal report should begin its substantive analysis with a clear articulation of the applicable burden of proof. Under 35 U.S.C. § 282, patents are presumed valid. This presumption of validity is a substantive rule of patent law that places the burden of proving invalidity squarely on the party challenging the patent — here, Lumicore. The standard of proof is clear and convincing evidence, which is a heightened standard significantly more demanding than the preponderance-of-the-evidence standard that applies in most civil matters. See Kestrel Partners LLC v. i4i Ltd. P'ship, 564 U.S. 91, 95 (2011) (holding that 35 U.S.C. § 282 requires an invalidity defense to be proved by clear and convincing evidence).
This burden applies equally to anticipation, obviousness, and prior-conception defenses. For anticipation under § 102, Lumicore must prove by clear and convincing evidence that a single prior-art reference discloses every element of an asserted claim, arranged as in the claim. For obviousness under § 103, Lumicore must prove by clear and convincing evidence that the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time of the invention to a person of ordinary skill in the art. For the prior-conception defense against the '015 Patent, Lumicore must prove by clear and convincing evidence that it conceived of the claimed invention prior to the '015 Patent's priority date and that such conception is corroborated by evidence beyond the testimony of the alleged inventor.
Dr. Ashford should note in her rebuttal report that Dr. Sundaram's opinions fail to meet this heightened burden for each asserted patent. In particular, Dr. Ashford should identify the specific respects in which Dr. Sundaram's analysis is deficient — whether through reliance on references that do not disclose every claim limitation, through proposed obviousness combinations that lack a proper motivation to combine, through hindsight-driven reconstruction of the claimed inventions, or through uncorroborated assertions regarding prior conception.
The presumption of validity is further strengthened with respect to prior-art references that were considered by the examiner during prosecution. Several of the prior-art references cited in Lumicore's invalidity contentions — most notably Takahashi — were before the examiner during prosecution of one or more of the asserted patents. The Federal Circuit has held that when the prior art relied upon to challenge validity was before the examiner during prosecution, the challenger's burden of overcoming the presumption of validity is particularly heavy. See Tokai Corp. v. Easton Enters., Inc., 632 F.3d 1358, 1367 (Fed. Cir. 2011). Dr. Ashford's rebuttal should highlight this principle wherever applicable.
B. Rebuttal Structure for Each Reference
To ensure thoroughness and clarity, Dr. Ashford's rebuttal report should follow a consistent structure for each prior-art reference addressed. This structured approach will facilitate both the drafting process and the reader's comprehension, and will ensure that no reference or claim limitation is inadvertently overlooked. For each prior-art reference cited by Dr. Sundaram, the rebuttal should proceed as follows:
(1) Identification of the Reference. The rebuttal should identify the reference by its full citation, including the author(s), title, publication venue, publication date, and any patent or application number, as applicable. The reference should be cross-referenced to Lumicore's P.R. 3-3 Invalidity Contentions and to the corresponding exhibits served therewith.
(2) Identification of Claims. The rebuttal should identify the specific claims of the relevant asserted patent that Lumicore asserts are anticipated or rendered obvious by the reference, either alone or in combination with other references.
(3) Claim-Limitation Mapping. The rebuttal should identify the specific claim limitations that Dr. Sundaram maps to the reference and the basis for each mapping, as presented in Dr. Sundaram's opening report and/or Lumicore's invalidity contentions.
(4) Demonstration of Missing or Undisclosed Limitations. The rebuttal should demonstrate, through detailed element-by-element analysis, that one or more limitations of the asserted claims are missing from or not disclosed by the reference. This demonstration should be supported by citation to the reference itself, to the patent specification, and to the prosecution history, as appropriate.
(5) Obviousness-Specific Rebuttal. Where obviousness is asserted, the rebuttal should go beyond the identification of missing limitations and should also demonstrate: (a) lack of motivation to combine the cited references; (b) evidence that the prior art teaches away from the claimed combination; (c) the absence of a reasonable expectation of success; and (d) that the proposed combination reflects impermissible hindsight reconstruction using the patent itself as a roadmap.
(6) Secondary Considerations. For each asserted claim, the rebuttal should address the applicable secondary considerations of non-obviousness, including commercial success, long-felt but unsolved need, failure of others, copying, and industry praise and licensing.
This structure should be applied consistently throughout the rebuttal report, with detailed claim charts provided in Appendix A for each reference-claim combination.
C. Secondary Considerations of Non-Obviousness (Global)
Secondary considerations of non-obviousness — often referred to as "objective indicia" or the "Graham factors" — are an essential component of the obviousness analysis and must be given appropriate weight. See Graham v. John Deere Co., 383 U.S. 1 (1966); Camberwell & Co. v. Northgate & Co. Elecs. Co., 839 F.3d 1034, 1052 (Fed. Cir. 2016) (en banc) ("[O]bjective indicia of nonobviousness must be considered before a conclusion on obviousness is reached and are not just a secondary consideration."). Dr. Ashford's rebuttal report should address secondary considerations both as a standalone section and through cross-references within each patent-specific rebuttal section.
The evidence supporting secondary considerations was compiled in Calderwood & Harkness LLP's December 2024 internal memorandum entitled "Secondary Considerations of Non-Obviousness — Evidentiary Summary" and is summarized below:
Commercial Success. OWS's products that practice the asserted patents — specifically, the OWS-400ZR, OWS-800XR, and OWS-1600DR product families — generated approximately $310 million of OWS's total $487.3 million fiscal year 2023 revenue, as reported in OWS's audited financial statements prepared by Gresham & Whitfield LLP (OWS's independent auditor). This revenue represents approximately 63.6% of OWS's total revenue and demonstrates the substantial commercial success of products embodying the patented technology. The gross margin on these practicing products was approximately 47.3%, further demonstrating the market value attributable to the patented innovations. For the commercial success evidence to be probative, a nexus must be established between the patented features and the commercial success. As discussed in the patent-specific sections below, the patented features — low-insertion-loss waveguide multiplexing, integrated coherent optical transceiver design, embedded micro-channel thermal management, and polarization-diverse grating coupling — are key differentiating features of OWS's products and are identified in OWS's marketing materials, customer specifications, and competitive analyses as primary drivers of customer demand.
Long-Felt but Unsolved Need. The silicon photonics industry had long sought to achieve low-insertion-loss waveguide multiplexing for dense wavelength-division multiplexing (DWDM) applications. Prior to the inventions disclosed in the '847 Patent, multiple research groups and commercial entities attempted to develop silicon photonic waveguide multiplexers with insertion losses below 1.0 dB per channel, but these efforts were unsuccessful. The industry recognized that reducing insertion loss was critical to enabling higher-bandwidth optical interconnects, as evidenced by published roadmaps from the Silicon Photonics Alliance and presentations at the Optical Fiber Communication Conference (OFC) between 2010 and 2015. The '847 Patent's solution to this long-felt need — through the use of tapered waveguide transitions and adiabatic mode converters — represented a significant advance that the industry had been unable to achieve despite sustained effort.
Failure of Others. At least three competitors — including Ashbury & Co., Inc. (now Westvale Group), Granite Harbor Enterprises, and Sterling Reach & Co., Inc. — attempted similar waveguide multiplexer designs before OWS's innovations were made and failed to achieve comparable insertion-loss levels. Documentary evidence of these failures includes published technical papers, conference presentations, and product datasheets from these competitors, which report insertion losses in the range of 2.0–4.0 dB per channel — significantly higher than the sub-1.0 dB performance achieved by OWS's patented designs. This evidence will be compiled and cited in the rebuttal report.
Copying. There is compelling evidence that Lumicore copied OWS's patented designs. At her deposition on November 19, 2024, Dr. Sandra Michaud, Lumicore's Chief Technology Officer, admitted under oath that she and members of Lumicore's engineering team reviewed OWS's published patent application No. 2018/0123456, which corresponds to the '193 Patent, during the design phase for Lumicore's LumiLink 400G-ZR+ transceiver product in 2021 and 2022. Dr. Michaud's testimony is further supported by the anticipated testimony of Melissa Chen, a former Lumicore engineer who is now employed by Veridian Photonics, Inc. Ms. Chen is expected to describe — either in a declaration or at her deposition (subpoena issued January 22, 2025) — how Lumicore's design team accessed and reviewed OWS's published patent applications during the 2021–2022 product design phase and how specific design features of the LumiLink 400G-ZR+ were developed with reference to OWS's disclosed innovations. Evidence of copying is particularly probative of non-obviousness because it demonstrates that even a sophisticated competitor found it necessary to look to the patentee's work rather than the prior art to develop a competing product. See Iron Grip Barbell Co. v. USA Sports, Inc., 392 F.3d 1317, 1325 (Fed. Cir. 2004).
Industry Praise and Licensing. OWS has entered into three license agreements covering the asserted patents: (1) the OWS-Terralink Semiconductor License Agreement (effective March 2022); (2) the OWS-NovaWave Corp. License Agreement (effective August 2022); and (3) the OWS-Helix Integrated Photonics License Agreement (effective January 2023). The willingness of three independent industry participants to take licenses on the asserted patents — rather than design around the patented technology — reflects industry recognition of the value and significance of the patented inventions. Additionally, OWS's patented technology has been recognized in industry publications, including articles in IEEE Spectrum, Lightwave, and Semiconductor Engineering, as well as through the receipt of multiple industry awards for the OWS-800XR product line.
IV. REBUTTAL — U.S. PATENT NO. 10,234,847 ("THE '847 PATENT")
A. Patent Overview (for Context in Report)
U.S. Patent No. 10,234,847 (the "'847 Patent"), entitled "Multi-Channel Silicon Photonic Waveguide Multiplexer with Low Insertion Loss," is one of the four patents asserted by OWS in this litigation. The '847 Patent was filed on September 14, 2016, and issued on March 19, 2019. The original and current assignee of the '847 Patent is Optiwave Semiconductor Corp. The named inventors include Dr. Jian-Wei Huang, who currently serves as OWS's Chief Technology Officer, along with co-inventors Dr. Priya Nair and Michael Torres. The '847 Patent and the '562 Patent (U.S. Patent No. 9,678,562) are in the same patent family and share a continuation relationship, with the '847 Patent being a continuation-in-part of the application that matured into the '562 Patent.
The '847 Patent is directed to a multi-channel silicon photonic waveguide multiplexer that achieves low insertion loss through the use of novel structural features, including tapered waveguide transitions and adiabatic mode converters, that minimize optical power loss at waveguide junctions and coupling regions. The patent specification discloses that the claimed multiplexer achieves insertion losses below 1.0 dB per channel across a broad wavelength range, which represented a significant improvement over the state of the art at the time of filing.
The claims asserted in this litigation are Claims 1, 3, 5, 9, and 14 of the '847 Patent. Claims 1 and 14 are independent claims; Claims 3, 5, and 9 are dependent claims. Claim 1 recites a multi-channel waveguide multiplexer comprising, among other elements, tapered waveguide transitions and adiabatic mode converters. Claim 3 depends from Claim 1 and adds a further limitation directed to the specific geometry of the tapered waveguide transition. Claim 5 depends from Claim 1 and adds a "mode-matched coupling region" limitation. Claim 9 depends from Claim 1 and contains a potentially means-plus-function limitation, as identified in Calderwood & Harkness LLP's October 5, 2024 means-plus-function analysis memorandum. Claim 14 is an independent claim that recites an "asymmetric directional coupler" as part of the multiplexer structure.
The identification of Claim 9 as potentially containing a means-plus-function limitation is significant for the validity analysis because, under 35 U.S.C. § 112(f) (pre-AIA § 112 ¶ 6), a means-plus-function claim is construed to cover the corresponding structure disclosed in the specification and equivalents thereof. If Claim 9 is construed as a means-plus-function claim, the prior art must disclose the specific structure (or an equivalent) identified in the '847 Patent specification as corresponding to the recited function — a more demanding requirement than simple element-by-element disclosure.
B. Prior-Art References Asserted Against the '847 Patent
Lumicore's P.R. 3-3 Invalidity Contentions cite six (6) prior-art references against the '847 Patent out of the twenty-three (23) total references cited across all four asserted patents. The key references requiring detailed rebuttal in Dr. Ashford's report are discussed below. The remaining references asserted against the '847 Patent will be addressed using the same element-by-element methodology once Dr. Sundaram's opening report is received and analyzed.
1. Takahashi et al., "Dense WDM Silicon Photonic MUX" (IEEE Photonics Technology Letters, March 2014)
Lumicore's Theory. Lumicore asserts that Takahashi et al. ("Takahashi") anticipates Claims 1, 3, and 14 of the '847 Patent under 35 U.S.C. § 102. Takahashi is a peer-reviewed journal article published in IEEE Photonics Technology Letters in March 2014, authored by researchers affiliated with Aldermere Holdings (NTT). The Takahashi reference describes an arrayed waveguide grating (AWG) multiplexer designed for dense wavelength-division multiplexing (DWDM) in silicon photonics applications. Lumicore contends that every limitation of Claims 1, 3, and 14 is disclosed in Takahashi.
Rebuttal Points. Dr. Ashford's rebuttal should demonstrate that Takahashi does not anticipate any of the asserted claims of the '847 Patent. Anticipation requires that a single prior-art reference disclose every element of a claim, arranged as in the claim. See Schering Corp. v. Geneva Pharm., Inc., 339 F.3d 1373, 1377 (Fed. Cir. 2003). Takahashi fails this test for multiple independent reasons.
First, while Takahashi discloses an arrayed waveguide grating (AWG) multiplexer for silicon photonics, it does not disclose the specific structural features that are the hallmark of the '847 Patent — namely, the "tapered waveguide transitions" and "adiabatic mode converters" recited in Claims 1 and 3. The Takahashi AWG design employs conventional star coupler geometry and uniform waveguide widths at the input and output ports, without the tapered transition structures claimed in the '847 Patent. The '847 Patent specification explains at length that it is precisely these tapered waveguide transitions and adiabatic mode converters that reduce insertion loss to below 1.0 dB per channel — a performance level that Takahashi does not achieve and does not purport to achieve. Takahashi reports measured insertion losses of greater than 2.5 dB per channel across the demonstrated wavelength range, which is substantially higher than the performance level associated with the structural features claimed in the '847 Patent.
Second, the specification of the '847 Patent defines "low insertion loss" in the context of the specific structural features — tapered waveguide transitions and adiabatic mode converters — that reduce loss below 1.0 dB per channel. While "low insertion loss" is a relative term that must be understood in the context of the specification and prosecution history, the claimed structural features that produce this performance characteristic are expressly recited in the claims and are absent from Takahashi. Thus, Takahashi does not merely fail to achieve the claimed performance; it fails to disclose the structural means by which that performance is achieved, and those structural means are expressly claimed.
Third, Takahashi does not disclose the "asymmetric directional coupler" limitation recited in independent Claim 14. The Takahashi AWG design utilizes a star coupler (also known as a slab coupler) for distributing optical signals among the arrayed waveguides, not an asymmetric directional coupler. A star coupler and an asymmetric directional coupler are fundamentally different optical coupling structures, operating on different physical principles and exhibiting different performance characteristics. A POSITA would immediately recognize the distinction between these two structures and would not equate them. Lumicore's apparent attempt to map Takahashi's star coupler to the '847 Patent's "asymmetric directional coupler" limitation reflects a fundamental misunderstanding — or deliberate mischaracterization — of the claimed invention.
Fourth, this rebuttal is supported by and cross-referenced to Calderwood & Harkness LLP's internal invalidity analysis memorandum for the '847 Patent, dated November 1, 2024, which identifies these same missing limitations and concludes that Takahashi does not anticipate any of the asserted claims. That analysis was prepared by Omar Siddiqui and reviewed by Wendy Schultz and should be provided to Dr. Ashford for reference during the preparation of her rebuttal report.
Fifth, Dr. Ashford should provide detailed element-by-element claim charts, to be included as part of Appendix A to the rebuttal report, comparing the disclosures of Takahashi to each limitation of Claims 1, 3, and 14. These claim charts should identify, for each limitation, (a) the specific language of the claim limitation, (b) the construction of any disputed claim terms (as adopted by the Court at the March 14, 2025 Markman hearing or, if the Markman order has not yet issued, under both parties' proposed constructions), (c) the corresponding disclosure (if any) in Takahashi, and (d) the specific basis for concluding that the limitation is not disclosed. Where Takahashi is entirely silent as to a limitation, the chart should so state. Where Takahashi discloses a related but different structure, the chart should explain the distinction and why the related structure does not satisfy the claim limitation.
Finally, Dr. Ashford should note that Takahashi was before the examiner during prosecution of the '847 Patent and was considered during the examination process. The fact that the examiner was aware of Takahashi and nevertheless allowed the claims further supports the conclusion that Takahashi does not anticipate. Lumicore's reliance on a reference already considered and distinguished by the examiner carries a heightened burden under Tokai Corp., 632 F.3d at 1367.
2. PCT/EP2015/071234 (Simonsen) (Published September 17, 2015)
Lumicore's Theory. Lumicore asserts that the combination of Simonsen (PCT International Publication No. WO 2016/042123, published from application PCT/EP2015/071234, filed September 17, 2015) with Takahashi renders obvious Claims 1, 5, and 9 of the '847 Patent under 35 U.S.C. § 103. Simonsen is a PCT application published by the European Patent Office and authored by researchers affiliated with a Scandinavian photonics research institute. The Simonsen application describes a Mach-Zehnder interferometer (MZI)-based optical multiplexer for silicon photonic applications.
Rebuttal Points. Dr. Ashford's rebuttal should demonstrate that the combination of Simonsen with Takahashi does not render obvious any of the asserted claims of the '847 Patent. The obviousness analysis under § 103 requires consideration of: (1) the scope and content of the prior art; (2) the differences between the prior art and the claims; (3) the level of ordinary skill in the art; and (4) any objective indicia of non-obviousness. See Graham v. John Deere Co., 383 U.S. at 17–18.
First, Simonsen relates to a fundamentally different multiplexer architecture from both Takahashi and the '847 Patent. Simonsen discloses a Mach-Zehnder interferometer (MZI)-based multiplexer, which operates on the principle of constructive and destructive interference between split optical paths of different lengths. By contrast, Takahashi discloses an arrayed waveguide grating (AWG) multiplexer, which operates on the principle of wavelength-dependent diffraction through an array of waveguides with precisely controlled path-length differences. The '847 Patent claims a multiplexer that employs tapered waveguide transitions, adiabatic mode converters, and (in certain claims) asymmetric directional couplers — structural features that are not characteristic of either MZI-based or AWG-based architectures. The Simonsen MZI design does not disclose the same waveguide coupling geometry as the '847 Patent, and combining Simonsen with Takahashi would not result in the claimed invention.
Second, there is no proper motivation to combine Simonsen with Takahashi. The two references address different design philosophies for achieving wavelength multiplexing in silicon photonics: Takahashi pursues an AWG approach, while Simonsen pursues an MZI approach. A POSITA would not combine these two fundamentally different approaches without the benefit of hindsight knowledge derived from the '847 Patent itself. The Supreme Court's decision in KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), expanded the inquiry into motivation to combine beyond the rigid "teaching, suggestion, or motivation" test, but it did not eliminate the requirement that the combination be supported by some articulated reason or rationale. Merely identifying two references that both relate to the same general field (silicon photonics) is not sufficient to establish a motivation to combine them in the specific manner proposed by Lumicore. Dr. Ashford should explain in detail why a POSITA working in the silicon photonics field in 2016 would not have been motivated to combine an AWG multiplexer design with an MZI multiplexer design in order to arrive at the claimed invention.
Third, Simonsen's teachings would affirmatively teach away from the specific tapered transition structures claimed in the '847 Patent. Simonsen's MZI design relies on abrupt waveguide junctions and 3 dB splitters to achieve the desired interferometric effect. Simonsen specifically notes that tapered transitions at the MZI junctions would alter the splitting ratio and degrade the multiplexer's performance. Thus, not only does Simonsen fail to disclose the tapered waveguide transitions of the '847 Patent, it teaches away from their use. A reference that teaches away from the claimed invention cannot properly be relied upon to establish obviousness. See In re Gurley, 27 F.3d 551, 553 (Fed. Cir. 1994) ("A reference may be said to teach away when a person of ordinary skill, upon reading the reference, would be discouraged from following the path set out in the reference, or would be led in a direction divergent from the path that was taken by the applicant.").
Fourth, even if the combination were proper, it still fails to disclose the "mode-matched coupling region" limitation recited in Claim 5. Claim 5 depends from Claim 1 and requires a "mode-matched coupling region" between adjacent waveguide channels. Neither Takahashi nor Simonsen discloses a mode-matched coupling region. Takahashi's AWG design employs free-propagation regions (star couplers) rather than mode-matched coupling, and Simonsen's MZI design employs evanescent directional couplers that are not mode-matched. The combination of these two references, even taken together, does not account for this missing limitation.
Fifth, regarding Claim 9, which contains a potentially means-plus-function limitation, the corresponding structure identified in the '847 Patent specification is a specific integrated monitoring photodetector arrangement with feedback-controlled tuning elements. This corresponding structure is not disclosed in either Simonsen or Takahashi, individually or in combination. If Claim 9 is construed under § 112(f), the prior art must disclose the corresponding structure or its equivalent, and neither reference does so. Dr. Ashford should provide a detailed analysis of the corresponding structure as identified in the patent specification and should explain why neither Takahashi nor Simonsen discloses that structure or any equivalent thereof.
Sixth, Dr. Ashford should address Dr. Sundaram's likely reliance on extrinsic evidence — such as textbook definitions, dictionary entries, or general technical references — to fill the gaps in the Takahashi-Simonsen combination. While extrinsic evidence may be considered in claim construction, the intrinsic record (claims, specification, and prosecution history) controls. See Phillips v. AWH Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005) (en banc). Dr. Sundaram cannot properly rely on extrinsic evidence to supply claim limitations that are absent from the cited prior-art references. To the extent Dr. Sundaram's analysis depends on such gap-filling, it reflects impermissible hindsight reconstruction — using the patent itself as a blueprint and then selecting and combining pieces of the prior art to re-create the invention after the fact. See In re McLaughlin, 443 F.2d 1392, 1395 (CCPA 1971) ("Any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning, but so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper.").
3. Other References Asserted Against the '847 Patent
Dr. Ashford's rebuttal report should address each additional prior-art reference cited by Dr. Sundaram against the '847 Patent claims, beyond Takahashi and Simonsen, using the same element-by-element methodology set forth above. For each such reference, the rebuttal should: (1) identify the reference and the claims it is asserted against; (2) identify the invalidity theory (anticipation or obviousness); (3) provide a detailed element-by-element analysis demonstrating missing claim limitations; (4) for obviousness theories, demonstrate the lack of motivation to combine, any teaching-away evidence, and any hindsight-driven reasoning; and (5) address the applicable secondary considerations of non-obviousness.
These additional references cannot be fully identified and analyzed until Dr. Sundaram's opening report is received. However, based on the six references identified in Lumicore's P.R. 3-3 Invalidity Contentions as directed to the '847 Patent, we anticipate that the remaining references (beyond Takahashi and Simonsen) may include one or more of the following: additional academic publications relating to AWG or echelle grating multiplexer designs, patents or patent applications relating to waveguide taper geometries for non-photonic applications, and general textbook references on integrated optics. For each, Dr. Ashford should be prepared to demonstrate that the reference either (a) does not pertain to the specific field of silicon photonic waveguide multiplexing, (b) does not disclose the claimed structural features, or (c) does not provide the necessary motivation to combine when relied upon in an obviousness analysis.
Dr. Ashford should also cross-reference Calderwood & Harkness LLP's claim-differentiation analysis memorandum, dated October 8, 2024, which addresses the relationship between independent Claim 1 and dependent Claims 3 and 5 of the '847 Patent. Lumicore may argue that independent Claim 1 should be narrowly construed in light of the limitations added by dependent Claims 3 and 5, effectively importing dependent-claim limitations into the independent claim. Dr. Ashford should rebut this argument by noting that the doctrine of claim differentiation creates a presumption that each claim has a different scope, and that dependent claims are presumed to be narrower than the independent claims from which they depend. See Phillips, 415 F.3d at 1314–15. Thus, independent Claim 1 should be construed to have broader scope than Claims 3 and 5, and the analysis of whether a prior-art reference anticipates or renders obvious Claim 1 should be conducted without importing the additional limitations of the dependent claims.
C. Secondary Considerations Specific to the '847 Patent
In addition to the global secondary considerations discussed in Section III.C above, Dr. Ashford's rebuttal should address the specific nexus between the secondary considerations evidence and the '847 Patent claims.
Commercial Success. OWS's OWS-400ZR and OWS-800XR product families both embody the waveguide multiplexer design claimed in the '847 Patent. These products accounted for a substantial portion of the approximately $310 million in practicing-product revenue generated by OWS in fiscal year 2023. The specific nexus between the '847 Patent claims and the commercial success of these products is established by the fact that the low-insertion-loss waveguide multiplexer is a key selling point of these products, as confirmed by OWS's marketing materials, product datasheets, customer specifications, and competitive win/loss analyses. Customers specifically cite low insertion loss as a primary purchasing criterion, and OWS's products achieve the lowest insertion-loss levels in the industry — a performance advantage directly attributable to the structural features claimed in the '847 Patent.
Industry Adoption. The industry has broadly adopted OWS's multiplexer design approach, with several competitors — including Lumicore itself — employing tapered waveguide transition structures in their silicon photonic multiplexer designs after the publication of OWS's patent applications. This industry-wide adoption further demonstrates the significance and non-obviousness of the '847 Patent's claimed inventions.
Nexus. The nexus between the claimed features and the commercial success is clear and direct: the low-insertion-loss waveguide multiplexer is the specific feature that differentiates OWS's products from the competition and drives customer demand. See Ormco Corp. v. Align Tech., Inc., 463 F.3d 1299, 1312 (Fed. Cir. 2006) (requiring a nexus between the patented features and the asserted objective evidence of non-obviousness). Dr. Ashford should articulate this nexus clearly and should support it with specific references to OWS's marketing materials, customer testimonials, competitive analyses, and product specifications.
V. REBUTTAL — U.S. PATENT NO. 10,891,193 ("THE '193 PATENT")
A. Patent Overview
U.S. Patent No. 10,891,193 (the "'193 Patent"), entitled "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate," is the second of the four patents asserted by OWS in this litigation. The '193 Patent was filed on April 7, 2017, and issued on January 12, 2021. The original and current assignee of the '193 Patent is Optiwave Semiconductor Corp. The '193 Patent shares Provisional Application No. 62/499,117, filed April 7, 2017, with the '015 Patent (U.S. Patent No. 11,402,015), meaning that both patents claim priority to the same provisional application.
The '193 Patent is directed to a high-bandwidth coherent optical transceiver that is integrated on a silicon substrate using semiconductor fabrication processes. The patent specification describes a complete transceiver architecture that includes a coherent detection module, an integrated modulator array, waveguide routing structures, and electronic driver and receiver circuitry, all fabricated on or within a silicon-based wafer. The claimed transceiver design represented a significant advance over prior-art transceiver designs, which typically employed discrete components assembled on separate substrates and interconnected through external optical and electrical interfaces.
The claims asserted in this litigation are Claims 1, 3, 7, 10, 15, and 18 of the '193 Patent. Claims 1 and 10 are independent claims; Claims 3, 7, 15, and 18 are dependent claims. Claim 1 recites a coherent optical transceiver integrated on a silicon substrate, comprising a coherent detection module and an integrated modulator array, among other elements. Claim 10 recites a method for fabricating such a transceiver. Claim 15 contains a potentially means-plus-function limitation, as identified in Calderwood & Harkness LLP's October 5, 2024 means-plus-function analysis memorandum. Claims 3 and 7 are also subject to OWS's doctrine of equivalents (DOE) infringement contentions, which may implicate prosecution history estoppel considerations that intersect with the validity rebuttal.
B. Prior-Art References Asserted Against the '193 Patent
Lumicore's P.R. 3-3 Invalidity Contentions cite eight (8) prior-art references against the '193 Patent, making it the most heavily challenged of the four asserted patents in terms of the number of cited references. The following discussion addresses the key references requiring detailed rebuttal.
1. Takahashi et al. (IEEE Photonics Technology Letters, March 2014)
Lumicore's Theory. Lumicore asserts that Takahashi anticipates Claims 1 and 10 of the '193 Patent under 35 U.S.C. § 102. As noted above, Takahashi is the same reference asserted against the '847 Patent. Lumicore contends that Takahashi discloses every limitation of Claims 1 and 10, including the "coherent optical transceiver integrated on a silicon substrate" and its component elements.
Rebuttal Points. Dr. Ashford's rebuttal should demonstrate that Takahashi does not anticipate either Claim 1 or Claim 10 of the '193 Patent. The rebuttal should address the following specific points:
First, Takahashi is focused on waveguide multiplexing — specifically, arrayed waveguide grating (AWG) multiplexer design — and does not disclose a "coherent optical transceiver integrated on a silicon substrate" as claimed in the '193 Patent. The scope of Takahashi's disclosure is limited to the multiplexing subsystem; it does not describe a complete transceiver architecture, let alone one that integrates coherent detection, modulation, and electronic control functions on a single silicon substrate. A waveguide multiplexer is a component of a transceiver, but it is not a transceiver. Lumicore's assertion that Takahashi discloses the entire transceiver architecture claimed in the '193 Patent is simply wrong.
Second, Takahashi does not disclose the "coherent detection module" limitation recited in Claim 1. The '193 Patent claims a transceiver that includes a "coherent detection module" — a specific optical subsystem that performs coherent detection of incoming optical signals by mixing the incoming signal with a local oscillator and detecting the resulting interference pattern to recover both amplitude and phase information. Coherent detection is a fundamentally different detection modality from the direct (intensity-based) detection that is implicit in Takahashi's AWG multiplexer design. Takahashi does not discuss coherent detection in any form, and no structure in Takahashi could reasonably be mapped to the "coherent detection module" limitation.
Third, Takahashi does not disclose the "integrated modulator array" limitation of Claim 1. The '193 Patent claims a transceiver that includes an "integrated modulator array" — an array of optical modulators that are fabricated on the same silicon substrate as the other transceiver components and that modulate the optical carrier signal with data for transmission. Takahashi's AWG multiplexer does not include any modulator structures, nor does it describe modulation of optical signals. An AWG multiplexer is a passive optical device; it does not modulate signals.
Fourth, and critically, the '193 Patent was narrowed during prosecution in response to a § 102 rejection over Takahashi. Specifically, during prosecution of the application that matured into the '193 Patent, the examiner issued an office action rejecting certain claims under § 102 based on Takahashi. In response, OWS amended the claims to narrow the "coherent detection module" limitation, adding language that further defined the structure and function of the coherent detection module in a manner that clearly distinguished it from Takahashi's disclosure. The examiner thereafter withdrew the § 102 rejection and allowed the amended claims. This prosecution history confirms the examiner's own conclusion that Takahashi does not anticipate the claims as issued, and it further strengthens the presumption of validity with respect to this reference.
Dr. Ashford should cross-reference Calderwood & Harkness LLP's prosecution history estoppel analysis for the '193 Patent, dated October 10, 2024, which addresses the implications of the narrowing amendment for the doctrine of equivalents analysis on Claims 3 and 7. The narrowing amendment was made specifically to overcome Takahashi, which confirms that the resulting claims are patentably distinct from Takahashi's disclosure. For the validity rebuttal, this prosecution history is highly probative: Lumicore's reliance on the very reference that was considered and overcome during prosecution, without identifying any new argument or analysis not already presented to and rejected by the examiner, should be given little weight. Dr. Ashford should emphasize that the examiner's determination, made with the benefit of full examination of Takahashi, supports the conclusion that Takahashi does not anticipate the '193 Patent claims as issued.
Dr. Ashford should address this issue carefully in light of the prosecution history estoppel implications for the doctrine of equivalents analysis on Claims 3 and 7. While prosecution history estoppel is a separate legal doctrine from validity, the rebuttal report should clearly explain that the narrowing amendment was made to distinguish Takahashi and that the resulting claims are patentably distinct. The report should not, however, make concessions or statements that could be used against OWS in the separate DOE infringement analysis. This requires careful drafting and close coordination between Dr. Ashford and the Calderwood & Harkness LLP litigation team.
2. Additional References Against the '193 Patent
Dr. Ashford's rebuttal report should address each of the remaining seven (7) prior-art references cited in Lumicore's invalidity contentions against the '193 Patent. These references cannot be fully analyzed in this outline because their specific content and Dr. Sundaram's mappings thereof are not yet available. However, the following framework should guide the analysis for each reference:
"Integrated on a Silicon Substrate" Limitation. For each reference, Dr. Ashford should specifically assess whether the reference discloses the "integrated on a silicon substrate" limitation, which is a key disputed claim term in this case. OWS's proposed construction of this term is "formed on or within a silicon-based wafer using semiconductor fabrication processes," which encompasses both monolithic and hybrid integration approaches. Lumicore's proposed construction would require "monolithic fabrication without hybrid bonding," which is narrower and would exclude transceiver designs that employ heterogeneous integration techniques. The construction adopted by the Court at the March 14, 2025 Markman hearing will be critical to the validity analysis. If the Court adopts OWS's broader construction, many prior-art references will be further distinguished because even under the broader construction, most prior-art transceiver designs do not disclose the full integration of all claimed components — coherent detection module, integrated modulator array, waveguide routing, and electronic circuitry — on a single silicon-based wafer. If the Court adopts Lumicore's narrower construction, different prior-art references may or may not qualify as disclosing this limitation, depending on whether they describe monolithically fabricated structures.
"Coherent Detection Module" Limitation. For each reference, Dr. Ashford should assess whether the reference discloses the "coherent detection module" limitation as narrowed during prosecution. As discussed above, this limitation was amended during prosecution to overcome a § 102 rejection based on Takahashi, and the amended claim language imposes specific structural and functional requirements on the coherent detection module that many prior-art references will fail to meet.
"Integrated Modulator Array" Limitation. For each reference, Dr. Ashford should assess whether the reference discloses an "integrated modulator array" as recited in the claims. This limitation requires not merely the disclosure of optical modulators, but of an array of modulators integrated on the same silicon substrate as the other transceiver components.
Obviousness Combinations. For references asserted in § 103 combinations, Dr. Ashford should challenge the motivation to combine, demonstrate that proposed combinations still leave gaps in claim coverage, and address any teaching-away evidence. The analysis should follow the same framework set forth in Section III.B above.
Claim 15 Means-Plus-Function Analysis. For Claim 15, which contains a potentially means-plus-function limitation, Dr. Ashford should identify the corresponding structure disclosed in the '193 Patent specification and assess whether the prior art discloses that structure or an equivalent thereof. If the corresponding structure is a specific electronic control circuit architecture for managing coherent detection and modulation, as identified in C&H's October 5, 2024 analysis, it is unlikely that prior-art references focused on discrete-component transceiver designs will disclose this structure.
C. Interaction Between Claim Construction and Validity
The construction of the term "integrated on a silicon substrate" is critical to both the infringement and validity analyses in this case, and the two analyses interact in important ways. Dr. Ashford's rebuttal report should address the validity of the '193 Patent claims under both possible constructions of this term, with the primary analysis conducted under OWS's proposed construction and an alternative analysis conducted under Lumicore's proposed construction.
Under OWS's proposed construction ("formed on or within a silicon-based wafer using semiconductor fabrication processes"), the claims are broader in scope, which generally makes them harder to invalidate because the prior art must disclose the full range of structural features recited in the claims, not merely the integration approach. Most prior-art transceiver designs do not disclose the complete integration of coherent detection, modulation, waveguide routing, and electronic control on a silicon substrate, regardless of whether hybrid bonding is employed. Under this construction, several of Dr. Sundaram's anticipation arguments may become weaker because the prior art may fail to disclose integration on a silicon substrate even under the broader definition.
Under Lumicore's proposed construction ("monolithic fabrication without hybrid bonding"), the claims are narrower in scope. This narrower construction could theoretically make the claims either easier or harder to invalidate, depending on the specific prior art at issue. On the one hand, a narrower claim scope means that fewer prior-art references will fall within the claim's literal scope (and thus fewer references will serve as anticipatory art). On the other hand, a narrower claim scope may bring the claimed invention closer to certain prior-art disclosures of monolithically fabricated photonic circuits, potentially strengthening obviousness arguments.
Dr. Ashford should present her validity analysis under both constructions so that OWS is fully prepared regardless of the Court's claim construction ruling. This dual-construction approach will also demonstrate to the Court that the claims are valid under either construction, which strengthens OWS's overall position.
D. Secondary Considerations Specific to the '193 Patent
The coherent optical transceiver design embodied in OWS's OWS-800XR product was a significant market breakthrough. Prior to the OWS-800XR, no commercially available silicon photonic transceiver achieved the bandwidth, power efficiency, and integration density that the OWS-800XR demonstrated. The OWS-800XR was recognized with the "Product Innovation of the Year" award at the 2022 Optical Fiber Communication Conference (OFC) and was featured in cover articles in IEEE Spectrum (May 2022) and Lightwave (June 2022).
OWS's fiscal year 2023 revenue from products practicing the '193 Patent constituted a substantial portion of the approximately $310 million in practicing-product revenue described in Section III.C above. The precise allocation of revenue among the four asserted patents is addressed in the damages expert report, but it is clear that the '193 Patent's coherent transceiver claims cover technology that is central to OWS's highest-value product offerings.
The copying evidence is particularly strong with respect to the '193 Patent. As noted above, Dr. Sandra Michaud, Lumicore's Chief Technology Officer, admitted at her deposition on November 19, 2024, that she and members of Lumicore's engineering team reviewed OWS's published patent application No. 2018/0123456 — which directly corresponds to the '193 Patent — during the design phase for Lumicore's LumiLink 400G-ZR+ transceiver product in 2021 and 2022. This admission establishes that Lumicore was aware of OWS's patented design and had access to the detailed disclosure of the invention during the period when Lumicore was developing its own competing product. The anticipated testimony of Melissa Chen is expected to provide additional detail regarding the extent to which Lumicore's design team relied on OWS's published applications in d