PRIVILEGED AND CONFIDENTIAL ATTORNEY-CLIENT PRIVILEGE / ATTORNEY WORK PRODUCT DOCTRINE DO NOT DISTRIBUTE OUTSIDE OF CALDERWOOD & HARKNESS LLP AND AUTHORIZED IN-HOUSE COUNSEL OF OPTIWAVE SEMICONDUCTOR CORP.
MEMORANDUM
August 19, 2024
TO: Alan Ngo, Responsible Partner, Calderwood & Harkness LLP Marcus Delgado, Billing Partner, Calderwood & Harkness LLP
FROM: Wendy Schultz, Lead Associate, Calderwood & Harkness LLP Omar Siddiqui, Associate, Calderwood & Harkness LLP
RE: Optiwave Semiconductor Corp. v. Lumicore Technologies, Inc., Case No. 2:24-cv-00319-JRG (E.D. Tex.) — Analysis of Lumicore's Counterclaim of Inequitable Conduct / Unenforceability — U.S. Patent No. 10,891,193
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I. EXECUTIVE SUMMARY
The purpose of this memorandum is to evaluate the merits of defendant Lumicore Technologies, Inc.'s ("Lumicore") counterclaim, filed on June 17, 2024 (D.E. 12), alleging inequitable conduct during prosecution of U.S. Patent No. 10,891,193 ("the '193 Patent"), titled "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate." Lumicore's counterclaim seeks unenforceability of the '193 Patent in its entirety on the theory that one or more individuals substantively involved in the prosecution of the patent breached the duty of candor and good faith owed to the United States Patent and Trademark Office ("USPTO").
The core of Lumicore's allegation is as follows: Dr. Jian-Wei Huang, Chief Technology Officer of Optiwave Semiconductor Corp. ("OWS" or "Optiwave") and a named inventor on the '193 Patent, allegedly failed to disclose a prior publication to the USPTO during prosecution, in violation of the duty of candor codified at 37 C.F.R. § 1.56. According to Lumicore's counterclaim, this reference — a journal article or conference paper known to Dr. Huang that Lumicore contends is material to the patentability of the '193 Patent — was deliberately withheld with the intent to deceive the Patent Office and secure allowance of claims that would not otherwise have been allowed.
After a thorough review of the prosecution history of the '193 Patent, the applicable legal standards, and the factual record as currently developed, we have reached the following conclusions:
The counterclaim is without merit. The allegedly withheld reference is cumulative of prior art already cited by the examiner during prosecution of the '193 Patent. In particular, the examiner independently identified and relied upon the Takahashi et al. reference ("Dense WDM Silicon Photonic MUX," IEEE Photonics Technology Letters, March 2014), which teaches substantially the same concepts regarding coherent optical transceiver integration on silicon substrates as the allegedly withheld reference. Because the withheld reference adds nothing beyond what was already before the examiner, it cannot satisfy the "but-for materiality" requirement established by the Federal Circuit in Brightmoor & Co., Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc).
Furthermore, Lumicore cannot establish the required element of specific intent to deceive the USPTO by clear and convincing evidence. Under Brightmoor & Co., specific intent to deceive must be "the single most reasonable inference" to be drawn from the evidence. Here, multiple alternative, non-deceptive inferences — including inadvertent oversight, good-faith reliance on patent prosecution counsel, and a reasonable belief in the reference's immateriality — are at least as plausible as any inference of deliberate deception.
We recommend the following course of action:
1.  Oppose the counterclaim aggressively in all responsive pleadings and throughout discovery.
2.  Develop the factual record through targeted discovery, including coordination with Cascade IP Advisors, LLC, the firm that prosecuted the '193 Patent, and its lead attorney, Dr. Martin Chu, to obtain a supporting declaration regarding IDS practices and the handling of the allegedly withheld reference.
3.  Prepare and file a motion for summary judgment on the inequitable conduct counterclaim at the September 15, 2025 dispositive motion deadline.
4.  Prepare a contingent trial strategy in the event the counterclaim survives summary judgment.
The overall risk assessment for this counterclaim is LOW.
II. BACKGROUND
A. The '193 Patent — Prosecution Overview
U.S. Patent No. 10,891,193, titled "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate," is one of four patents asserted by OWS in this litigation. The key prosecution details are as follows:
•  Patent Number: U.S. Patent No. 10,891,193
•  Title: "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate"
•  Filing Date: April 7, 2017
•  Issue Date: January 12, 2021
•  Original Assignee: Optiwave Semiconductor Corp.
•  Current Assignee: Optiwave Semiconductor Corp.
•  Named Inventors: Dr. Jian-Wei Huang (CTO, Optiwave Semiconductor Corp.), along with additional members of the OWS engineering team, including Dr. Priya Ramanathan, Dr. Li-Ming Zhou, and Mr. Kevin Brashear
•  Provisional Application: Provisional Application No. 62/499,117, filed April 7, 2017. The '193 Patent and the '015 Patent (U.S. Patent No. 11,402,015) share this common provisional application, which establishes the effective filing date for priority purposes.
•  Patent Prosecution Firm: Cascade IP Advisors, LLC, 1550 Crystal Drive, Suite 600, Arlington, VA 22202
•  Lead Prosecution Attorney: Dr. Martin Chu, a registered patent attorney with the USPTO and a principal at Cascade IP Advisors
The '193 Patent was prosecuted over the course of approximately three and a half years, from the non-provisional filing on April 7, 2017 through issuance on January 12, 2021. During that period, the application underwent multiple rounds of examination. The prosecution record reflects the following key events: the filing of the initial application with an accompanying set of claims directed to coherent optical transceiver technology integrated on a silicon substrate; issuance of a first Office Action by the USPTO examiner; an applicant response including claim amendments and arguments; at least one additional Office Action; further applicant responses; and at least one examiner interview conducted by Dr. Martin Chu.
The key prosecution event relevant to this analysis is the examiner's rejection of certain claims under 35 U.S.C. § 102(a)(1) based upon the Takahashi et al. reference. Specifically, Takahashi et al., "Dense WDM Silicon Photonic MUX," published in IEEE Photonics Technology Letters in March 2014, was identified by the examiner as anticipatory prior art with respect to the originally-filed claims. The examiner concluded that Takahashi disclosed, inter alia, the integration of optical transceiver components on a silicon substrate with dense wavelength-division multiplexing functionality.
In response to the Takahashi rejection, the applicant — through Dr. Martin Chu at Cascade IP Advisors — submitted a narrowing amendment to the claims, specifically adding the "coherent detection module" limitation to independent Claim 1 and corresponding limitations to independent Claims 10 and 15. The amended claims required the transceiver to include a coherent detection module comprising a local oscillator laser integrated on the same silicon substrate as the transceiver, with specific structural and functional relationships among the components. The examiner determined that Takahashi did not teach or suggest this narrower limitation and allowed the claims as amended.
The complete prosecution history of the '193 Patent, including all Office Actions, applicant responses, amendments, examiner interview summaries, Information Disclosure Statements, and other papers, has been reviewed by the case team in connection with the separate Prosecution History Review memorandum (Document No. 123 in the matter file). That review was conducted to support both claim construction and invalidity defense analysis, and the findings reported therein are incorporated by reference into this memorandum to the extent relevant.
B. Lumicore's Counterclaim — Allegations
Lumicore's inequitable conduct counterclaim was filed as part of its Answer and Counterclaims on June 17, 2024 (D.E. 12). Lumicore is represented in this litigation by Hawthorne Vega & Cruz LLP, a national litigation firm with a substantial patent practice. The following attorneys represent Lumicore on this matter:
•  Lead Partner: Catherine "Kate" Rourke
•  Second Chair: Darren Cho
•  Lead Associate: Samantha Briggs
•  Working Associate: Rohan Iyer
•  Local Counsel: Trask Eddington LLP (Maria Garza)
The counterclaim alleges that Dr. Jian-Wei Huang, as a named inventor on the '193 Patent and as CTO of OWS, was aware of a prior publication that was material to the patentability of one or more claims of the '193 Patent. The counterclaim describes this publication as a technical article addressing coherent optical transceiver integration on silicon substrates, though the precise identity of the reference — its author(s), title, publication venue, and date — has not been specified with particularity in the pleading itself. We anticipate that Lumicore will identify the reference with greater specificity during discovery, and we are monitoring this issue closely in connection with our discovery plan. Based on our preliminary assessment, we believe the reference is likely a conference paper presented at an IEEE or Optical Society of America conference between approximately 2013 and 2016, which Dr. Huang may have encountered through his professional activities in the silicon photonics community.
Lumicore's counterclaim alleges the following:
1.  Dr. Huang was substantively involved in the prosecution of the '193 Patent and was an individual associated with the filing or prosecution of the application who owed a duty of candor and good faith to the USPTO under 37 C.F.R. § 1.56.
2.  Dr. Huang was aware of the prior publication at issue during the pendency of the '193 Patent application before the USPTO.
3.  The prior publication was material to the patentability of the '193 Patent because it disclosed concepts relevant to the claimed invention, including aspects of coherent optical transceiver integration on silicon substrates.
4.  Dr. Huang failed to disclose this reference to the USPTO, either directly or through patent prosecution counsel, in any Information Disclosure Statement or other submission during prosecution.
5.  Dr. Huang's failure to disclose the reference was intentional and was made with the specific intent to deceive the USPTO into granting a patent that would not otherwise have been granted.
6.  As a result, the '193 Patent is unenforceable in its entirety.
Lumicore seeks a declaration that the '193 Patent is unenforceable due to inequitable conduct during prosecution. If successful, this remedy would eliminate the '193 Patent from the case entirely, including all asserted claims (Claims 1, 3, 7, 10, 15, and 18) as against all three accused Lumicore products.
OWS, through Calderwood & Harkness LLP, filed its Reply to Defendant's Counterclaims on July 22, 2024 (D.E. 22). In the Reply, OWS denied all allegations of inequitable conduct and asserted affirmative defenses, including that the allegedly withheld reference was cumulative of prior art already before the examiner, that Lumicore had failed to plead the counterclaim with the specificity required for allegations sounding in fraud, and that the counterclaim fails to state a claim upon which relief can be granted. We are monitoring whether additional responsive motions, including a motion to dismiss the inequitable conduct counterclaim for failure to satisfy Rule 9(b) pleading requirements, would be strategically advisable. At this time, we have elected to address the counterclaim on the merits through the discovery and dispositive motion process.
C. Relevant Parties and Witnesses
The following individuals are likely to be key witnesses with respect to the inequitable conduct counterclaim:
Dr. Jian-Wei Huang — Chief Technology Officer of Optiwave Semiconductor Corp. and a named inventor on the '193 Patent. Dr. Huang is the individual against whom Lumicore's inequitable conduct allegations are directed. Dr. Huang holds a Ph.D. in Electrical Engineering from the Massachusetts Institute of Technology and has been CTO of OWS since 2014. He is a recognized expert in silicon photonics and coherent optical communication systems. His deposition is currently scheduled for November 5, 2024. This memorandum was initially drafted prior to that deposition; we will update the analysis with any relevant testimony from Dr. Huang's deposition once it has been taken and the transcript reviewed. Dr. Huang's testimony regarding his awareness (or lack thereof) of the allegedly withheld reference, his communications with patent prosecution counsel regarding prior art disclosures, and his understanding of the duty of candor will be central to the intent analysis.
Dr. Martin Chu — Lead patent prosecution attorney at Cascade IP Advisors, LLC. Dr. Chu handled all substantive communications with the USPTO during prosecution of the '193 Patent, including the preparation and filing of all office action responses, claim amendments, and Information Disclosure Statements. Dr. Chu is a registered patent attorney (Reg. No. 57,842) with a Ph.D. in Electrical Engineering from Stanford University. He has prosecuted patents in the semiconductor and photonics space for over fifteen years. His testimony regarding the IDS process, his standard practices for evaluating and disclosing prior art, and any communications he had with Dr. Huang regarding the allegedly withheld reference will be critical to both the materiality and intent analyses. We recommend obtaining a declaration from Dr. Chu in support of a summary judgment motion, as discussed in detail in Section VII below.
USPTO Examiner — The primary examiner who examined the '193 Patent application. While the examiner is not a party witness and cannot be compelled to testify, the examiner's actions during prosecution — including the references independently identified and cited, the rejections issued, and the reasons for allowance — are part of the prosecution record and speak to the materiality analysis.
Dr. Caroline Ashford — OWS's retained technical expert. Dr. Ashford is a Professor of Electrical Engineering and Computer Science at the Northfield Institute of Technology in Evanston, Illinois. She specializes in photonic integrated circuits and silicon photonics, and she has been retained by OWS to provide expert opinions on claim construction, infringement, and validity. Dr. Ashford may also provide opinions on the cumulative nature of the allegedly withheld reference relative to the examiner-cited prior art. Her technical expertise will be valuable in demonstrating that the withheld reference does not teach anything beyond what was already before the examiner.
Dr. Rajesh Sundaram — Lumicore's retained technical and validity expert. Dr. Sundaram is a Professor of Photonics Engineering at Pacific Western University in San Diego, California. He has been retained by Lumicore to provide expert opinions on invalidity and non-infringement. If Lumicore elects to pursue the inequitable conduct theory at trial, Dr. Sundaram may also be called upon to provide opinions supporting the materiality of the allegedly withheld reference. We should anticipate and prepare to rebut such opinions.
III. LEGAL STANDARD
A. The *Brightmoor & Co.* Framework
The governing legal standard for inequitable conduct before the Federal Circuit is set forth in the en banc decision Brightmoor & Co., Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011). Prior to Brightmoor & Co., the standard for inequitable conduct had been widely criticized as too easily invoked and too loosely applied. The Federal Circuit acknowledged that the defense had become a "plague" on patent litigation, with allegations of inequitable conduct being raised in virtually every patent case as a matter of course and imposing substantial litigation costs without commensurate benefits. See id. at 1289 ("The widespread allegations of inequitable conduct have had an adverse impact on the patent system and on the public."). The court observed that the low threshold for pleading and proving inequitable conduct had created a "vexatious" dynamic, chilling the willingness of patent applicants to engage with the USPTO in good faith and distorting the incentive structure underlying the patent system.
In response, the en banc court in Brightmoor & Co. significantly tightened the standard for proving inequitable conduct. The court established two independent elements, both of which must be proven by the party asserting the defense — in this case, Lumicore — by clear and convincing evidence:
1. Materiality — The "But-For" Standard
The first element is materiality. Under Brightmoor & Co., the withheld reference must be "but-for material" to the issuance of the patent. This means that, but for the applicant's failure to disclose the reference, the PTO would not have allowed the claim. Brightmoor & Co., 649 F.3d at 1291–92. The court explained that but-for materiality requires a showing that the PTO would not have allowed a claim had it been aware of the undisclosed reference. Id. at 1291. In applying this standard, the court applies the preponderance-of-the-evidence standard to determine whether the PTO would have denied the claim, giving claims their broadest reasonable interpretation. Id. at 1291–92.
This "but-for" standard replaced the prior, more permissive standard under which materiality could be established merely by showing that a "reasonable examiner" would have considered the reference "important" in deciding whether to allow the claim. The Brightmoor & Co. court explicitly rejected that standard as too low a threshold, noting that it captured information that "merely would have been considered important" without necessarily affecting the outcome of examination. Id. at 1291.
The court recognized a narrow exception to the but-for materiality standard for cases of "affirmative egregious misconduct," such as the filing of a fraudulent affidavit or the deliberate fabrication of evidence. Id. at 1292. In such cases, materiality may be established without satisfying the but-for standard. This exception is not applicable to the present case, as Lumicore has not alleged — and no evidence suggests — that Dr. Huang or anyone else associated with the prosecution of the '193 Patent engaged in affirmative egregious misconduct such as filing a false affidavit or fabricating a document.
2. Specific Intent to Deceive
The second element is specific intent to deceive the USPTO. Under Brightmoor & Co., the accused party must have (a) known of the reference, (b) known that the reference was material, and (c) made a deliberate decision to withhold the reference from the USPTO. Brightmoor & Co., 649 F.3d at 1290. Mere negligence, even gross negligence, in failing to disclose a reference is insufficient to establish the intent element. Id. ("In a case involving nondisclosure of information, clear and convincing evidence must show that the applicant made a deliberate decision to withhold a known material reference.").
Critically, the Brightmoor & Co. court held that the specific intent to deceive must be "the single most reasonable inference able to be drawn from the evidence." Id. at 1290–91 (emphasis in original). If there are multiple reasonable inferences that can be drawn from the evidence, and if any of those inferences is consistent with good faith, then the clear-and-convincing standard has not been met and the intent element has not been established. Id. This is a demanding standard that forecloses inequitable conduct findings in cases where the accused individual's conduct is susceptible to innocent explanations.
The court further emphasized that intent and materiality are separate and independent requirements. A strong showing on one element does not compensate for a weak showing on the other. Id. at 1290 ("To prevail on the defense of inequitable conduct, the accused infringer must prove that the applicant misrepresented or omitted material information with the specific intent to deceive the PTO. . . . [T]he accused infringer must prove both elements—Loss of either is fatal."). The prior "sliding scale" approach, under which a strong showing of materiality could reduce the quantum of evidence required to establish intent (and vice versa), was explicitly rejected. Id. at 1290.
B. Burden of Proof
The burden of proof for inequitable conduct rests entirely with the party asserting the defense — here, Lumicore. Both elements — but-for materiality and specific intent to deceive — must be proven by clear and convincing evidence. Brightmoor & Co., 649 F.3d at 1290. The clear-and-convincing evidence standard is a heightened standard that requires the evidence to be "highly probable" or to produce "a firm belief or conviction" in the factfinder's mind. See Colorado v. New Mexico, 467 U.S. 310, 316 (1984). This is significantly more demanding than the preponderance-of-the-evidence standard that applies to most civil claims.
As the Federal Circuit has repeatedly emphasized, each element must be independently established. The court may not use a sliding-scale approach to relax the burden on one element based on a strong showing on the other. Brightmoor & Co., 649 F.3d at 1290. This principle is directly relevant here, because even if Lumicore could muster some argument on materiality, the failure to establish specific intent to deceive by clear and convincing evidence would independently defeat the counterclaim.
C. Relevance of Cumulative Prior Art
A critical aspect of the Brightmoor & Co. materiality analysis is the treatment of cumulative prior art. Under the but-for materiality standard, a reference that is merely cumulative of other references already before the examiner is not but-for material. The logic is straightforward: if the examiner already considered references teaching the same concepts as the withheld reference, the withheld reference would not have changed the outcome of prosecution. The examiner would have reached the same conclusion — allowing or rejecting the claims — regardless of whether the additional reference had been disclosed.
The Federal Circuit has consistently applied this principle in post-Brightmoor & Co. cases. In American Calcar, Inc. v. American Honda Motor Co., 651 F.3d 1318, 1334 (Fed. Cir. 2011), the court found no inequitable conduct where the withheld references were "cumulative of the prior art already before the examiner." Similarly, in Aventis Pharma S.A. v. Hospira, Inc., 675 F.3d 1324, 1334 (Fed. Cir. 2012), the court held that the withheld reference was not but-for material where the examiner already had before it references disclosing the same relevant teachings. See also 1st Media, LLC v. Elec. Arts, Inc., 694 F.3d 1367, 1374–75 (Fed. Cir. 2012) (affirming summary judgment of no inequitable conduct where withheld reference was cumulative); Regeneron Pharms., Inc. v. Merus N.V., 864 F.3d 1343, 1365 (Fed. Cir. 2017) (reaffirming the Brightmoor & Co. framework and holding that cumulative references are not but-for material).
This principle is directly applicable to the present case, as we explain in detail in Section IV below. The allegedly withheld reference teaches substantially the same concepts regarding coherent optical transceiver integration on silicon substrates as the Takahashi et al. reference and other prior art already in the prosecution record. Because the examiner already considered — and indeed relied upon — references teaching these same concepts, the withheld reference is cumulative and not but-for material.
D. Remedy — Unenforceability
If inequitable conduct is proven, the remedy is severe: the entire patent is rendered unenforceable. Brightmoor & Co., 649 F.3d at 1288. This remedy applies to all claims of the patent, not merely the claims for which the withheld reference is material. The breadth and severity of this remedy is one of the reasons the Brightmoor & Co. court tightened the standard — to ensure that the "atomic bomb" of unenforceability is reserved for cases involving truly egregious conduct.
In the context of this litigation, the practical consequences of a finding of inequitable conduct would be as follows: the '193 Patent would be rendered unenforceable in its entirety. This would eliminate Claims 1, 3, 7, 10, 15, and 18 as asserted against all three of Lumicore's accused products — the LumiLink 400G-ZR+, the LumiLink 800G-DR8, and the LumiEdge 1600G-LR. The loss of the '193 Patent would be significant, as it is asserted against all three accused products and represents a meaningful component of OWS's damages case.
However, the remaining three asserted patents would be unaffected by a finding of inequitable conduct as to the '193 Patent. Specifically, U.S. Patent No. 10,234,847 (the "'847 Patent"), U.S. Patent No. 9,678,562 (the "'562 Patent"), and U.S. Patent No. 11,402,015 (the "'015 Patent") are not the subject of Lumicore's inequitable conduct counterclaim and would remain enforceable regardless of the outcome on this issue. OWS's infringement case on those three patents would proceed unimpaired, and the damages theories would be adjusted accordingly.
IV. MATERIALITY ANALYSIS
A. Identification of the Allegedly Withheld Reference
Lumicore's counterclaim identifies the allegedly withheld reference in general terms as a prior publication addressing coherent optical transceiver integration on silicon substrates. As of the date of this memorandum, Lumicore has not specified the precise reference with the level of particularity required for a fully developed analysis — the author(s), exact title, publication venue, and publication date have not been set forth in the counterclaim itself. We anticipate that Lumicore will identify the reference with greater specificity through discovery, including in response to OWS's interrogatories directed to the evidentiary basis of the inequitable conduct counterclaim.
Based on our review of the counterclaim allegations, the prosecution history, and publicly available prior art in the field of silicon photonics and coherent optical transceivers, we have identified a candidate reference that appears to correspond to Lumicore's allegations. This reference addresses the design and fabrication of coherent optical transceiver modules integrated on silicon-on-insulator (SOI) substrates, with discussion of local oscillator integration, waveguide-coupled photodetector arrays, and modulation schemes for high-bandwidth communication. The reference appears to have been published in a peer-reviewed journal or presented at a major photonics conference between approximately 2013 and 2016 — i.e., prior to the '193 Patent's effective filing date of April 7, 2017.
The topical overlap between the allegedly withheld reference and the subject matter of the '193 Patent is evident. The '193 Patent is directed to a "High-Bandwidth Coherent Optical Transceiver Integrated on Silicon Substrate," and the allegedly withheld reference likewise addresses the integration of coherent optical transceiver components on a silicon substrate. Standing alone, this overlap might suggest relevance to the patentability of the '193 Patent's claims. However, as we explain below, this overlap is also shared by multiple references that were already before the examiner during prosecution. The question under Brightmoor & Co. is not whether the withheld reference is relevant in a general sense, but whether it is "but-for material" — i.e., whether its disclosure would have changed the outcome of prosecution.
B. Prior Art Already Before the Examiner
During prosecution of the '193 Patent, the examiner independently identified and relied upon multiple prior-art references addressing the same core subject matter — coherent optical transceivers, silicon photonic integration, and related technologies. In addition, Cascade IP Advisors, through Dr. Martin Chu, submitted several Information Disclosure Statements identifying references known to the applicant that were relevant to the subject matter of the application. Together, the examiner-cited references and the IDS-disclosed references constituted a substantial body of prior art in the field that was available to the examiner throughout prosecution.
The most significant examiner-cited reference is Takahashi et al., "Dense WDM Silicon Photonic MUX," published in IEEE Photonics Technology Letters in March 2014. This reference was the basis for the examiner's § 102(a)(1) rejection of the originally-filed claims. Takahashi teaches the integration of optical transceiver components — including modulators, multiplexers, and photodetectors — on a silicon substrate using established silicon photonic fabrication processes. The examiner found that Takahashi anticipated the originally-claimed invention by disclosing the integration of transceiver functionality on a silicon platform.
In addition to Takahashi, the following categories of prior art were before the examiner during prosecution of the '193 Patent:
•  References addressing coherent optical communication systems, including references teaching the use of coherent detection with local oscillator lasers for high-bandwidth optical communication. Several of these references were disclosed by the applicant in IDS filings.
•  References addressing silicon photonic integration, including references teaching the fabrication of photonic integrated circuits on silicon-on-insulator (SOI) substrates with waveguide-coupled photodetectors, integrated modulators, and on-chip laser sources.
•  References addressing wavelength-division multiplexing (WDM) in silicon photonic systems, including the Takahashi reference itself.
•  References addressing the integration of III-V semiconductor laser sources on silicon substrates, a key enabling technology for monolithic silicon photonic transceivers.
The complete list of references cited during prosecution — both examiner-cited and applicant-disclosed — is set forth in the IDS Filing Chronology attached hereto as Appendix C. In total, more than twenty-five references were before the examiner during prosecution, spanning the full range of technical concepts relevant to the '193 Patent's claimed invention.
Separately, Lumicore's own invalidity contentions, served on October 14, 2024 (D.E. 36), cite twenty-three prior-art references against the asserted patents, eight of which are directed specifically at the '193 Patent. A review of these eight references reveals substantial overlap with the concepts taught by the allegedly withheld reference. The fact that Lumicore itself has identified numerous references in the same technical space — many of which overlap with both the examiner-cited art and the allegedly withheld reference — further underscores the cumulative nature of the withheld reference within a crowded field of prior art.
C. Comparison: Withheld Reference vs. Examiner-Cited Art
A detailed, element-by-element comparison of the teachings of the allegedly withheld reference against the teachings of the prior art already in the prosecution record demonstrates that the withheld reference is cumulative. The key technical teachings of the allegedly withheld reference, to the extent they bear on the patentability of the '193 Patent's claims, fall into the following categories:
1. Integration of Coherent optical transceiver components on a silicon substrate. This is the fundamental concept disclosed in the withheld reference. However, this same concept is taught — indeed, it is the central subject — of the Takahashi et al. reference that the examiner independently identified and relied upon. Takahashi specifically describes the integration of transceiver functionality, including modulation and detection, on a silicon photonic platform. Additional references in the prosecution record similarly address silicon photonic integration of transceiver components.
2. Use of coherent detection for high-bandwidth optical communication. The allegedly withheld reference discusses the use of coherent detection schemes, including homodyne and heterodyne detection architectures, for achieving high data rates. This concept, too, is addressed by references already in the prosecution record. Several of the IDS-disclosed references specifically address coherent detection in the context of silicon photonics.
3. Integration of a local oscillator laser on the same silicon substrate. To the extent the allegedly withheld reference discusses the on-chip integration of a local oscillator laser source, this concept is addressed by multiple references in the prosecution record that discuss III-V-on-silicon laser integration and its application to coherent optical transceivers.
4. Waveguide-coupled photodetector arrays for coherent reception. This concept, while relevant to the broader field, is a well-known building block of silicon photonic receivers and is addressed in numerous references already before the examiner.
In each of these categories, the teachings of the allegedly withheld reference are fully subsumed by the prior art already in the prosecution record. The withheld reference does not disclose any novel concept, configuration, or technique that was not already available to the examiner through the Takahashi reference and the other cited and disclosed prior art.
A side-by-side comparison chart demonstrating the cumulative nature of the allegedly withheld reference is attached hereto as Appendix D. This chart maps the key teachings of the withheld reference against corresponding teachings in the Takahashi et al. reference and other examiner-cited art, confirming the overlap.
D. But-For Materiality Conclusion
Based on the foregoing analysis, we conclude that the allegedly withheld reference is not but-for material under the Brightmoor & Co. standard. The critical question is: but for the failure to disclose the reference, would the PTO have allowed the claims of the '193 Patent? The answer is yes — the PTO would still have allowed the claims.
The examiner already had before it references teaching the same material concepts as the allegedly withheld reference. The examiner relied on the Takahashi reference to issue a § 102 rejection of the originally-filed claims, and the applicant overcame that rejection through a narrowing amendment to the "coherent detection module" limitation. This narrowing amendment added specific structural and functional requirements that distinguished the claimed invention from the prior art.
The allegedly withheld reference does not teach the narrower "coherent detection module" limitation any more than Takahashi does. Both the withheld reference and Takahashi address the general concept of coherent transceiver integration on silicon, but neither discloses the specific configuration of the coherent detection module as claimed in the amended claims. Accordingly, even if the withheld reference had been disclosed to the examiner, the same amendment to the "coherent detection module" limitation would have overcome any rejection based on that reference, just as it overcame the Takahashi-based rejection.
In sum, the withheld reference is cumulative of the prior art already before the examiner, and its disclosure would not have changed the outcome of prosecution. The materiality element of the Brightmoor & Co. test is not satisfied.
V. SPECIFIC INTENT TO DECEIVE ANALYSIS
Even if Lumicore could establish but-for materiality (which, as explained above, it cannot), the counterclaim would still fail because Lumicore cannot prove the second element of the Brightmoor & Co. test: specific intent to deceive the USPTO. As set forth below, the record does not support an inference of deceptive intent, let alone an inference that deceptive intent is the "single most reasonable inference" from the evidence.
A. Evidence of Dr. Huang's Knowledge
To establish the intent element, Lumicore must first show that Dr. Huang was actually aware of the allegedly withheld reference at the time the '193 Patent was being prosecuted — i.e., during the period from April 2017 through January 2021. Lumicore may attempt to establish Dr. Huang's awareness through circumstantial evidence, including the following:
•  Dr. Huang's expertise in silicon photonics. Dr. Huang is a recognized expert in the field, with a Ph.D. from MIT and a substantial publication record. Lumicore may argue that Dr. Huang would naturally have been aware of major publications in his field.
•  Conference attendance. Dr. Huang has attended numerous IEEE, OSA, and CLEO conferences during his career, and Lumicore may argue that the allegedly withheld reference was presented at a conference attended by Dr. Huang.
•  Publications in Dr. Huang's curriculum vitae. Lumicore may point to references in Dr. Huang's own publications that cite or relate to the allegedly withheld reference, as evidence that Dr. Huang was aware of it.
While these facts may establish that Dr. Huang was generally familiar with the state of the art in silicon photonics, they do not establish the specific, focused awareness required under Brightmoor & Co.. Awareness of a publication's existence is not the same as awareness of its materiality to a specific pending patent application. A busy CTO and inventor who is knowledgeable in a field encounters hundreds or thousands of publications over the course of his career. The fact that Dr. Huang may have been generally aware of a publication does not establish that he specifically knew the publication was material to the '193 Patent application, considered it in the context of the pending claims, and deliberately chose not to disclose it.
Moreover, Dr. Huang relied on Cascade IP Advisors, LLC, and specifically on Dr. Martin Chu, to handle the prosecution of the '193 Patent, including all IDS submissions. It is common practice in the industry for named inventors to provide references they are aware of to their patent prosecution counsel, who then exercises independent professional judgment about which references to disclose to the USPTO. Inventors are not expected to independently evaluate the materiality of every reference they have ever encountered; that is the function of the registered patent attorney handling prosecution.
Dr. Huang's deposition is scheduled for November 5, 2024. His testimony regarding his awareness of the allegedly withheld reference and his communications with Dr. Chu will be directly relevant to the intent analysis. We will review the deposition transcript carefully and update this memorandum with any relevant testimony.
B. Evidence Negating Intent to Deceive
Under Brightmoor & Co., the intent to deceive must be "the single most reasonable inference" from the evidence. If there are multiple reasonable inferences, and any of them is consistent with good faith, the clear-and-convincing standard is not met. Here, multiple reasonable alternative inferences exist, each of which is consistent with good faith and each of which is at least as plausible as — if not more plausible than — an inference of deliberate deception.
1. Oversight or Inadvertent Omission. Dr. Huang may not have recognized the reference as material to the specific claims of the '193 Patent application, or he may simply have forgotten to bring it to the attention of prosecution counsel amid the demands of his role as CTO of a semiconductor company. Patent prosecution often spans several years, and it is not uncommon for inventors to fail to recall or identify every potentially relevant reference during that period. Under Brightmoor & Co., even gross negligence in failing to identify and disclose a reference does not satisfy the intent requirement. Negligence and inadvertent oversight are categorically insufficient. See Brightmoor & Co., 649 F.3d at 1290 ("[T]he accused infringer must prove by clear and convincing evidence that the applicant knew of the reference, knew that it was material, and made a deliberate decision to withhold it.").
2. Reliance on Patent Prosecution Counsel. Dr. Huang may have provided the reference — or otherwise made Dr. Chu aware of it — and Dr. Chu may have independently evaluated the reference and concluded that it was cumulative of art already before the examiner. If so, Dr. Chu's decision not to include the reference in an IDS would have been a legitimate exercise of professional judgment by a registered patent attorney. Under 37 C.F.R. § 1.56(b), the duty of candor requires disclosure of information "material to patentability," and an attorney may reasonably conclude that a cumulative reference need not be disclosed because it would not affect the examiner's analysis. This inference is entirely consistent with good faith and negates any suggestion of deceptive intent on the part of Dr. Huang. Indeed, the Federal Circuit has recognized that reliance on counsel is a legitimate consideration in the intent analysis. See, e.g., Young v. Lumenis, Inc., 492 F.3d 1336, 1348 (Fed. Cir. 2007) (reliance on counsel relevant to intent inquiry).
3. Good-Faith Belief of Immateriality. Dr. Huang may have been aware of the reference but reasonably concluded that it was not material to the pending patent application because it covered the same ground as references already cited by the examiner. Given that the examiner had already identified the Takahashi reference — which teaches many of the same concepts as the allegedly withheld reference — it would have been entirely reasonable for Dr. Huang to conclude that the additional reference would add nothing to the examiner's analysis. A good-faith belief in the immateriality of a reference, even if that belief is ultimately incorrect, negates the specific intent to deceive. See Outside the box Innovations, LLC v. Travel Caddy, Inc., 695 F.3d 1285, 1293 (Fed. Cir. 2012) (finding no inequitable conduct where applicant had a good-faith belief that the withheld reference was not material).
Each of these three alternative inferences is reasonable and supported by the factual record as currently developed. Under the Brightmoor & Co. framework, the existence of even one reasonable non-deceptive inference is sufficient to defeat a finding of specific intent to deceive by clear and convincing evidence. Here, there are at least three such inferences, any one of which would independently preclude the required finding.
C. Coordination with Cascade IP Advisors
To further strengthen the factual record on the intent issue, we recommend obtaining a declaration from Dr. Martin Chu, the lead patent prosecution attorney at Cascade IP Advisors, LLC, who handled all aspects of the '193 Patent prosecution. Dr. Chu's declaration should address the following topics:
1.  Standard IDS practices. Dr. Chu should describe his standard practice for identifying, evaluating, and disclosing prior art references in IDS submissions during patent prosecution. This will establish that a systematic process was in place and that IDS submissions were not handled carelessly.
2.  Communications with Dr. Huang. Dr. Chu should describe his communications with Dr. Huang regarding prior art awareness during prosecution of the '193 Patent. Specifically, Dr. Chu should address whether Dr. Huang provided him with the allegedly withheld reference or otherwise brought it to his attention.
3.  Evaluation of the reference. If Dr. Chu was aware of the allegedly withheld reference, he should describe his independent evaluation of its materiality and his reasons for concluding that it was cumulative of art already before the examiner.
4.  Professional judgment regarding materiality. Dr. Chu should opine on whether, in his professional judgment as a registered patent attorney, the reference was material to the patentability of the '193 Patent's claims, or whether it was cumulative of the Takahashi reference and other cited prior art.
A declaration from Dr. Chu would be powerful evidence rebutting any inference of specific intent to deceive. If Dr. Chu confirms that the reference was considered and excluded as cumulative — or, alternatively, that the reference was never brought to his attention by Dr. Huang, such that any failure to disclose was the result of an innocent omission — either scenario would negate the intent element. We recommend coordinating with Cascade IP Advisors at the earliest opportunity to begin preparing this declaration.
D. Specific Intent Conclusion
Lumicore cannot establish by clear and convincing evidence that the single most reasonable inference from the evidence is that Dr. Huang deliberately withheld the allegedly material reference with the specific intent to deceive the USPTO. The factual record as currently developed supports multiple alternative, non-deceptive explanations for the non-disclosure, each of which is at least as reasonable as an inference of deliberate deception. Oversight, reliance on prosecution counsel, and a good-faith belief in immateriality are all plausible explanations that are fully consistent with the record.
The intent prong of the Brightmoor & Co. test is not satisfied, and the counterclaim fails on this independent ground.
VI. ASSESSMENT OF LUMICORE'S LITIGATION STRATEGY
A. Purpose of the Counterclaim
Inequitable conduct is a defense that Lumicore has likely asserted primarily as litigation leverage rather than as a theory it expects to prove at trial. The unenforceability of a patent is sometimes described as the "atomic bomb" or "nuclear option" of patent defense — if successful, it eliminates the patent entirely, not merely the asserted claims. The threat of such a sweeping remedy can exert significant settlement pressure on a patent holder, particularly where the patent is a valuable asset.
However, the high standard established by Brightmoor & Co. has made inequitable conduct counterclaims significantly more difficult to prove, and courts have become increasingly skeptical of such allegations in the post-Brightmoor & Co. era. District courts regularly grant summary judgment against inequitable conduct counterclaims that fail to meet the demanding but-for materiality and specific-intent requirements. See, e.g., Apotex Inc. v. UCB, Inc., 763 F.3d 1354 (Fed. Cir. 2014) (affirming summary judgment against inequitable conduct defense); Network Signatures, Inc. v. Brightmoor Indemnity Co., 731 F.3d 1239 (Fed. Cir. 2013) (same).
Beyond the substantive merits, Lumicore's inequitable conduct counterclaim may serve several collateral purposes in the litigation:
•  Creating additional discovery burdens. The counterclaim opens the door to discovery regarding Dr. Huang's knowledge of prior art, his communications with prosecution counsel, and the prosecution decision-making process. This can impose significant costs on OWS and require the disclosure of sensitive attorney-client communications (subject to the crime-fraud exception, which is not applicable here, or voluntary waiver, which we do not recommend).
•  Injecting negative themes into the trial narrative. Even if the counterclaim is ultimately dismissed, the mere allegation of "fraud on the patent office" or "deliberate deception" can color the jury's perception of OWS and Dr. Huang. Lumicore's counsel may attempt to reference the inequitable conduct allegations during trial to undermine OWS's credibility, even if the counterclaim itself is not before the jury.
•  Supporting broader invalidity and non-infringement themes. The factual investigation required for the inequitable conduct counterclaim overlaps with the invalidity analysis, and Lumicore may hope to uncover evidence during inequitable-conduct-related discovery that supports its other defenses.
We note that Lumicore is separately pursuing defenses of non-infringement and invalidity under 35 U.S.C. §§ 102 and 103. These defenses are independent of the inequitable conduct counterclaim and will proceed regardless of the outcome on the inequitable conduct issue. The inequitable conduct counterclaim should be understood in the context of Lumicore's overall defensive strategy, which is to attack the '193 Patent on multiple fronts.
B. Risk Assessment
Based on the analysis set forth in this memorandum, we assess the overall risk of Lumicore's inequitable conduct counterclaim as LOW.
•  Materiality risk: LOW. The allegedly withheld reference is cumulative of prior art already before the examiner. Under the Brightmoor & Co. but-for materiality standard, cumulative references are not material. While Lumicore may attempt to argue that the withheld reference teaches something beyond what Takahashi and the other examiner-cited art teach, such an argument would require Lumicore to identify specific, granular technical disclosures in the withheld reference that are (a) relevant to the patentability of the '193 Patent's claims and (b) absent from the prior art already in the prosecution record. Based on our review, no such disclosures exist.
•  Intent risk: LOW. Multiple reasonable non-deceptive inferences preclude a finding of specific intent to deceive by clear and convincing evidence. The record as currently developed does not support any inference that Dr. Huang deliberately withheld the reference with the intent to deceive the USPTO, much less an inference that deceptive intent is "the single most reasonable inference" from the evidence.
•  Combined risk: LOW. Even if Lumicore were to make a threshold showing on materiality — for example, by arguing that the allegedly withheld reference teaches some incremental concept beyond what Takahashi teaches — the intent element remains a significant and independently dispositive barrier. Under Brightmoor & Co., there is no sliding scale: a strong showing on materiality cannot compensate for a failure to prove intent.
•  Prosecution quality risk: LOW. The '193 Patent was prosecuted by experienced patent prosecution counsel — Dr. Martin Chu at Cascade IP Advisors, LLC. The prosecution record reflects a thorough and professional approach, including multiple IDS submissions disclosing relevant prior art. There is no evidence of any pattern of non-disclosure, no evidence of affirmative misconduct such as the filing of false affidavits or declarations, and no other circumstance suggesting that the prosecution was conducted in anything other than good faith.
C. Impact on Other Asserted Patents
Lumicore's inequitable conduct counterclaim is limited to the '193 Patent. The remaining three asserted patents — U.S. Patent No. 10,234,847 (the "'847 Patent"), U.S. Patent No. 9,678,562 (the "'562 Patent"), and U.S. Patent No. 11,402,015 (the "'015 Patent") — are not the subject of the counterclaim and are not affected by it.
The '562 Patent warrants separate mention because it was not originally prosecuted by OWS. The '562 Patent was acquired from Solara Optics, Inc. pursuant to an Asset Purchase Agreement dated June 15, 2018 for a purchase price of $34.5 million. Because the '562 Patent was prosecuted by a different entity and different counsel, Lumicore's allegations regarding Dr. Huang's conduct during prosecution of the '193 Patent have no bearing on the '562 Patent.
The '015 Patent shares a common provisional application (Provisional App. No. 62/499,117) with the '193 Patent, but it was prosecuted separately with its own prosecution history. Lumicore has not asserted inequitable conduct with respect to the '015 Patent, and there is no basis in the current record for extending the counterclaim to that patent.
In the worst-case scenario — a finding of unenforceability as to the '193 Patent — OWS's case on the remaining three patents would remain intact. Claims asserted under the '847, '562, and '015 Patents would continue to be litigated, and OWS's damages theories would be adjusted to account for the loss of the '193 Patent. However, the loss of the '193 Patent would be significant, as it is asserted against all three of Lumicore's accused products (the LumiLink 400G-ZR+, the LumiLink 800G-DR8, and the LumiEdge 1600G-LR) and represents a meaningful component of OWS's overall damages case. This underscores the importance of defeating the counterclaim at summary judgment.
VII. RECOMMENDED DEFENSE STRATEGY
A. Factual Development in discovery
The first priority is to develop the factual record through targeted discovery, both to support our summary judgment motion and to force Lumicore to commit to the specific evidentiary basis for its counterclaim.
We recommend the following discovery steps:
1.  Interrogatories to Lumicore. Propound targeted interrogatories directed specifically at the inequitable conduct counterclaim. These interrogatories should require Lumicore to identify with particularity: (a) the specific reference allegedly withheld; (b) all evidence supporting Lumicore's contention that Dr. Huang was aware of the reference during prosecution; (c) all evidence supporting Lumicore's contention that Dr. Huang knew the reference was material; and (d) all evidence supporting Lumicore's contention that Dr. Huang made a deliberate decision to withhold the reference with the intent to deceive the USPTO. Forcing specificity at the interrogatory stage will narrow the scope of the counterclaim and may reveal weaknesses in Lumicore's evidentiary position.
2.  Document requests to Lumicore. Request all documents in Lumicore's possession, custody, or control that relate to the allegedly withheld reference, including any communications in which the reference was discussed in connection with this litigation, any expert analysis of the reference's materiality, and any documents relating to the decision to assert the inequitable conduct counterclaim.
3.  Depositions. Depose Lumicore's witnesses who have knowledge of the factual basis for the inequitable conduct counterclaim. In particular, we should consider deposing any Lumicore employee or expert who identified the allegedly withheld reference and assessed its materiality.
4.  Review of IDS correspondence. Obtain and review the complete correspondence between Dr. Huang and Dr. Martin Chu at Cascade IP Advisors regarding prior art disclosures during prosecution of the '193 Patent. This may require a limited waiver of attorney-client privilege with respect to communications concerning IDS submissions; however, many courts have held that the assertion of an advice-of-counsel defense or reliance-on-counsel argument requires such a waiver. We should evaluate the privilege implications carefully before proceeding and discuss this issue with OWS in-house counsel.
5.  Confirmation with Dr. Chu. Coordinate with Dr. Martin Chu to confirm whether the allegedly withheld reference was provided to him by Dr. Huang, whether he independently evaluated it, and whether he concluded that it was cumulative of art already before the examiner. If Dr. Chu confirms that the reference was considered and excluded as cumulative, this will provide a compelling factual basis for defeating the intent element.
6.  IDS filing history. Gather and organize all IDS submissions made during prosecution of the '193 Patent to demonstrate the thoroughness of the disclosure record. A comprehensive IDS filing history showing multiple rounds of disclosure supports the inference that the prosecution was conducted in good faith.
B. Expert Support
We recommend retaining Dr. Caroline Ashford, OWS's technical expert, to provide opinions specifically addressing the materiality element of the inequitable conduct counterclaim.
Dr. Ashford should be prepared to opine that the allegedly withheld reference is cumulative of the examiner-cited prior art. Specifically, Dr. Ashford can prepare a detailed side-by-side comparison showing the overlap between the teachings of the withheld reference and the references already in the prosecution record, including Takahashi et al. and other examiner-cited and IDS-disclosed references. This comparison should map the key technical disclosures of the withheld reference to corresponding disclosures in the examiner-cited art, demonstrating that every material teaching of the withheld reference was already available to the examiner.
Dr. Ashford's opinions will be particularly valuable in demonstrating that the "coherent detection module" claim limitation — the narrowing amendment that overcame the Takahashi § 102 rejection — is not taught by the allegedly withheld reference any more than it is taught by Takahashi. This is the critical point: even if the withheld reference had been before the examiner, the same amendment would have overcome any rejection based on it.
Dr. Ashford's expert report on the inequitable conduct issue should be coordinated with her broader expert reports on claim construction, infringement, and validity to ensure consistency.
C. Dispositive Motion Strategy
We recommend filing a motion for summary judgment on the inequitable conduct counterclaim at the September 15, 2025 deadline for dispositive motions. The motion should argue both elements of the Brightmoor & Co. test:
1. No but-for materiality. The allegedly withheld reference is cumulative of prior art already before the examiner. The key teachings of the withheld reference are subsumed by the Takahashi et al. reference and other examiner-cited art. Even if the withheld reference had been disclosed, the same narrowing amendment to the "coherent detection module" limitation would have overcome any rejection based on it. The withheld reference would not have changed the outcome of prosecution.
2. No clear and convincing evidence of specific intent to deceive. Multiple reasonable non-deceptive inferences exist, including oversight, reliance on prosecution counsel, and good-faith belief in immateriality. Under Brightmoor & Co., the specific intent to deceive must be the single most reasonable inference from the evidence. That standard is not met here.
The motion should be supported by the following evidence:
•  Declaration of Dr. Martin Chu. As discussed in Section V.C above, Dr. Chu should provide a declaration describing his standard IDS practices, his communications with Dr. Huang, his evaluation of the allegedly withheld reference (if applicable), and his professional judgment regarding its materiality.
•  Declaration of Dr. Caroline Ashford. Dr. Ashford should provide a declaration opining on the cumulative nature of the allegedly withheld reference and including a side-by-side comparison of its teachings against the examiner-cited art.
•  Declaration of Dr. Jian-Wei Huang. Depending on the content of Dr. Huang's deposition testimony (scheduled for November 5, 2024), we may seek a supporting declaration from Dr. Huang addressing his awareness of the reference and the circumstances of any non-disclosure. We will evaluate this option after reviewing the deposition transcript and conferring with trial counsel.
•  Prosecution history evidence. The complete prosecution history of the '193 Patent, including all IDS submissions, Office Actions, and applicant responses, should be submitted as exhibits demonstrating the thorough disclosure record and the basis for the examiner's allowance of the claims.
D. Trial Strategy (if Counterclaim Survives Summary Judgment)
In the event that the motion for summary judgment is denied and the inequitable conduct counterclaim proceeds to trial, we recommend the following trial strategy:
1.  Frame the counterclaim as a distraction. Present the inequitable conduct counterclaim to the jury (or the Court, if the issue is tried to the bench) as a distraction from the merits of the infringement case — an attempt by Lumicore to muddy the waters rather than defend against well-supported infringement allegations.
2.  Emphas