ATTORNEY WORK PRODUCT — PRIVILEGED AND CONFIDENTIAL

ATTORNEY WORK PRODUCT — PRIVILEGED AND CONFIDENTIAL
DEPOSITION PREPARATION OUTLINE
HIDEO TANAKA
Named Inventor, U.S. Patent No. 10,234,567 Prior Art Inventor, U.S. Patent No. 9,456,012
Purpose: This memorandum constitutes a preparation outline for the deposition of Hideo Tanaka in connection with claim construction discovery in the above-captioned matter. The deposition is scheduled to occur prior to the October 31, 2022 close of claim-construction-related discovery as set forth in the Court's Case Management Order (Dkt. 42). This outline is intended for use exclusively by counsel at Calderwood & Harkness LLP in preparing for and conducting the Tanaka deposition and should be treated as attorney work product subject to the protections of Federal Rule of Civil Procedure 26(b)(3) and the attorney-client privilege to the extent applicable.
DESIGNATION: ATTORNEY WORK PRODUCT — PRIVILEGED AND CONFIDENTIAL NOT TO BE DISCLOSED TO WITNESS OR OPPOSING COUNSEL
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I. Witness Background and Biographical Information
This section sets forth the background information we have been able to assemble regarding Hideo Tanaka from publicly available sources, patent records, employment records produced in discovery, and internal OWS documents. A significant portion of this information remains subject to confirmation at the deposition itself, and the questioning outlined below is designed to fill gaps in our knowledge while establishing a complete record of Tanaka's qualifications, technical background, and potential biases.
A. Employment History
Hideo Tanaka is a former engineer at Optiwave Semiconductor Corp. ("OWS"). According to employment records produced by OWS in connection with this litigation, Tanaka was employed at OWS from approximately mid-2016 through 2019. His precise start and end dates should be confirmed during the deposition, as should his titles and areas of responsibility during his tenure.
Prior to joining OWS, Tanaka worked at another organization — the identity and nature of which remain to be confirmed — where he developed the technology underlying his prior art patent, U.S. Patent No. 9,456,012, which issued on September 6, 2016. The '456,012 patent is cited as "Tanaka et al.," suggesting that Tanaka was not the sole inventor and that the work was carried out in a collaborative environment, likely at a research institution or another semiconductor company. Establishing the identity of Tanaka's prior employer, the nature of his work there, and the circumstances under which the '456,012 patent was developed and assigned is important both for understanding the technical genealogy of the inventions at issue and for assessing any invention assignment obligations that may bear on Tanaka's credibility and potential interests.
Tanaka's current employment status and employer should be confirmed at the outset of the deposition. Tanaka is no longer employed by OWS and, based on preliminary communications through counsel, may be a potentially adverse or uncooperative witness. The circumstances of his departure from OWS in 2019 are not fully known to us and will need to be explored. It is important to establish at the earliest stage of the deposition whether Tanaka has any current relationship — whether employment, consulting, advisory, or otherwise — with Lumos Photonics, Inc. ("Lumos") or with Lumos's outside counsel, Brannick Howell & Stein LLP ("BHS"). Any such relationship would bear directly on Tanaka's credibility and potential bias and would need to be raised in connection with any motion to suppress or limit his testimony.
The following areas of inquiry should be covered in the opening segment of the deposition:
1.  Full name, current address (for service purposes), and current employer.
2.  Complete employment history from the completion of his education to the present, including dates, titles, and principal responsibilities at each position.
3.  The identity of his employer at the time the '456,012 patent was filed and issued, and the nature of his work there.
4.  The circumstances under which he joined OWS in 2016, including whether he was recruited by any specific individual (e.g., Dr. Kevin Fong or Dr. Priya Ramanathan).
5.  The circumstances under which he departed OWS in 2019, including whether the departure was voluntary or involuntary, and whether there were any disputes related to his departure.
6.  Any current or prior relationship, communication, or engagement with Lumos Photonics, Inc. or any of its officers, directors, employees, or agents.
7.  Any current or prior relationship, communication, or engagement with Brannick Howell & Stein LLP or any of its attorneys, including Victoria Ashworth, Daniel Kowalski, and Dr. Raymond Ng.
B. Educational Background
Tanaka's academic credentials should be confirmed to establish his qualifications as a person of ordinary skill in the art ("POSITA") and to lay the foundation for his testimony regarding the meaning of key claim terms in the '567 Patent. Based on the inventor information in the patent records and publicly available information, we expect Tanaka holds advanced degrees in a field related to electrical engineering, physics, or materials science, with a specialization in silicon photonics, waveguide design, or a closely related discipline within integrated photonics.
The following areas should be covered:
1.  Undergraduate institution, degree, major, and year of graduation.
2.  Graduate institution(s), degree(s), area(s) of specialization, thesis or dissertation topic(s), and year(s) of graduation.
3.  Any postdoctoral research or visiting researcher positions.
4.  Any continuing education, professional certifications, or industry training relevant to silicon photonics or integrated circuit design.
5.  The names of any academic advisors or mentors whose work is relevant to the technologies at issue in this litigation.
Establishing Tanaka's educational background serves a dual purpose. First, it confirms his qualifications to testify regarding the meaning of technical claim terms as understood by a POSITA at the time of the invention. Second, it may reveal connections to other researchers or institutions whose work has been cited as prior art in this litigation, including the authors of the Chen & Liu (2016) publication discussed in Section VII below.
C. Publications and Patents
Tanaka's full list of patents and publications should be confirmed to establish the breadth of his work in the field and to identify any additional prior art or technical disclosures that may be relevant to claim construction or validity issues in this case.
The two key patents with which Tanaka is associated are:
•  U.S. Patent No. 9,456,012 (the "prior art patent" or the "'456,012 patent"), issued September 6, 2016. This patent was developed prior to Tanaka's employment at OWS and has been cited by Lumos as prior art against the '567 Patent under 35 U.S.C. § 102(a)(1). It is discussed in detail in Section IV below.
•  U.S. Patent No. 10,234,567 (the "'567 Patent"), filed March 14, 2017 and issued March 19, 2019. Tanaka is one of three named co-inventors, along with Dr. Kevin Fong and Dr. Priya Ramanathan. The '567 Patent is one of the three patents-in-suit and is the primary focus of this deposition outline. It is discussed in detail in Sections II and III below.
In addition to these two patents, Tanaka may be a named inventor on other patents or patent applications, whether filed during his employment at OWS, at his prior employer, or subsequently. All such patents and applications should be identified and explored for potential relevance to the claim construction disputes at issue.
Tanaka should also be asked about any technical publications, conference presentations, or white papers he has authored or co-authored, particularly any relating to waveguide coupling, tapered mode converters, adiabatic coupling, silicon photonics integration, or related topics. Such publications may constitute additional prior art, may provide insight into how Tanaka understood and used key technical terms, and may contain statements that either support or undermine OWS's proposed claim constructions.
II. Tanaka's Role in the Invention of the '567 Patent
This section addresses Tanaka's involvement in the conception and reduction to practice of the invention claimed in U.S. Patent No. 10,234,567, which is at the center of this litigation. Understanding Tanaka's specific contributions, the timeline of the inventive process, and the relationship between the '567 Patent and Tanaka's prior art patent is essential to the claim construction issues before the Court.
A. Named Inventor on U.S. Patent No. 10,234,567
The '567 Patent is entitled "Integrated Waveguide Coupler with Tapered Mode Converter for Silicon Photonics Platforms." Tanaka is one of three named co-inventors, along with Dr. Kevin Fong, who serves as OWS's Chief Technology Officer and Co-Founder, and Dr. Priya Ramanathan, who serves as OWS's Chief Executive Officer and Co-Founder.
The relevant filing and prosecution dates are as follows:
In the present litigation, OWS has asserted Claims 1, 4, 7, 12, and 15 of the '567 Patent against Lumos. Claim 1 is the sole independent claim among those asserted and is the locus of the most significant claim construction dispute — specifically, the meaning of the term "adiabatically coupled," which is the subject of the parties' competing proposed constructions.
B. Conception and Development
Tanaka's deposition testimony should establish the full timeline of his contributions to the '567 Patent invention. The following areas of inquiry are critical:
Timeline of inventive activity. When did the inventive work that culminated in the '567 Patent begin? Was there a specific project at OWS under which this work was undertaken? Was it initiated by management (e.g., by Dr. Fong or Dr. Ramanathan), or did it emerge from Tanaka's own independent research activities? When did Tanaka first conceive of the specific inventive concepts reflected in the '567 Patent claims?
Individual contributions. What specific technical contributions did Tanaka make to the '567 Patent invention, as distinct from the contributions of Dr. Fong and Dr. Ramanathan? Were the three co-inventors working together as a team on a single project, or did their contributions arise from different streams of work that were later combined? Tanaka should be asked to describe in his own words what he personally invented or discovered that is reflected in the '567 Patent.
Documentation. What contemporaneous documentation exists that records Tanaka's inventive contributions? This should include laboratory notebooks, design files (e.g., CAD layouts, mask designs), simulation data (e.g., FDTD or beam propagation method simulations), internal OWS memoranda, email communications, and any invention disclosure forms filed with OWS's intellectual property department (which was overseen by Ted Marchetti, VP of IP).
Relationship to prior work. Did the work that led to the '567 Patent build upon, extend, or depart from Tanaka's earlier work reflected in U.S. Patent No. 9,456,012? This is a critical question, as the answer bears directly on both the claim construction and the prosecution history estoppel issues discussed below.
C. Relationship Between '567 Patent and Prior Art Patent (U.S. 9,456,012)
This is among the most critical areas of inquiry for the Tanaka deposition. Lumos has cited U.S. Patent No. 9,456,012 (Tanaka et al.) as prior art against the '567 Patent under 35 U.S.C. § 102(a)(1), and the prosecution history reveals that the claims of the '567 Patent were narrowed during prosecution specifically to overcome this prior art reference. The relationship between the two patents is central to both the claim construction and prosecution history estoppel disputes.
The following lines of inquiry should be pursued:
Scope of disclosure in the '456,012 patent. What did Tanaka disclose in the '456,012 patent regarding waveguide coupling techniques? What specific structures, methods, and performance characteristics are described? Does the '456,012 patent disclose anything that Tanaka would characterize as "adiabatic" coupling?
Technical distinctions. What does Tanaka identify as the key technical differences between his prior art invention (as described in the '456,012 patent) and the '567 Patent invention? Is the difference primarily structural (e.g., the geometry of the taper), functional (e.g., the mode transition characteristics), or both?
Narrowing of claims during prosecution. The claims of the '567 Patent were narrowed during prosecution to include the "adiabatically coupled" limitation specifically to overcome the Tanaka '456,012 prior art. What was Tanaka's understanding of why this limitation was added? Did Tanaka understand the addition of this term to be excluding all coupling structures other than continuous tapers, or did he understand it to be distinguishing the '567 Patent on the basis of the functional performance characteristic of low-loss mode transition?
Improvement or departure. Does the '567 Patent represent an incremental improvement over the approach described in the '456,012 patent, or does it reflect a fundamentally different approach to waveguide coupling? Tanaka's characterization of this relationship will be relevant to the estoppel analysis.
Participation in prosecution. Was Tanaka aware during prosecution of the '567 Patent application that his own prior patent was cited against the application by the examiner? Did Tanaka participate in or provide input to the prosecution strategy employed by Ted Marchetti and OWS's patent prosecution team? Was Tanaka consulted about the decision to add the "adiabatically coupled" limitation? Did Tanaka review or approve the applicant's remarks submitted in response to the office action rejections?
Each of these questions has the potential to generate testimony that either supports or undermines OWS's position on claim construction and prosecution history estoppel. Our preparation of Tanaka must account for the possibility that his answers may not align with OWS's litigation positions, and we must be prepared to manage adverse testimony through careful framing of the questions and, if necessary, through redirect or rehabilitation.
III. Understanding of Key Claim Terms — '567 Patent
The primary purpose of this deposition within the claim construction discovery phase is to elicit Tanaka's understanding of the disputed claim terms in the '567 Patent, particularly the term "adiabatically coupled" as used in Claim 1. The parties' competing proposed constructions present starkly different visions of the scope of the patent claims, and Tanaka's testimony — as a named inventor and as a POSITA with direct knowledge of the field — has the potential to be among the most influential evidence in the Markman hearing.
A. "Adiabatically Coupled" (Claim 1 — Key Disputed Term)
1. The Claim Language
Claim 1 of the '567 Patent is the sole independent claim among those asserted by OWS. It recites, in relevant part:
An integrated optical coupler comprising a tapered silicon waveguide having a tip width of less than 200 nanometers adiabatically coupled to a silicon nitride waveguide layer…
The term "adiabatically coupled" is the most significant disputed claim term in this litigation. The parties have submitted the following competing proposed constructions:
The dispute centers on a fundamental question: whether the term "adiabatically coupled" imposes a structural limitation requiring a continuous, gradual taper (as Lumos contends), or whether it is properly understood as a functional limitation describing the performance characteristic of the coupling — namely, that the mode transition occurs without significant power loss — regardless of the specific structural configuration employed to achieve that result (as OWS contends).
This distinction is outcome-determinative for the infringement analysis. If the Court adopts OWS's broader construction, the accused Lumos products — which employ segmented (non-continuous) taper designs — may be found to infringe. If the Court adopts Lumos's narrower construction, Lumos will argue that its segmented taper design falls outside the literal scope of the claims.
2. Tanaka's Understanding of "Adiabatically Coupled"
The deposition should elicit Tanaka's understanding of the term "adiabatically coupled" as of the time of the invention (circa 2016–2017) and explore the basis for that understanding. The following lines of questioning should be pursued:
General understanding. How does Tanaka define or understand the term "adiabatic" as used in the context of optical waveguide coupling? What does "adiabatically coupled" mean to him as a person working in the field of silicon photonics?
Usage in Tanaka's own work. How did Tanaka use the term "adiabatic" in his own technical work, both at OWS and in his prior employment? Did Tanaka use the term in the '456,012 patent? If so, how was it defined or used in that context? Did Tanaka use the term differently at OWS than he did in his earlier work?
Structural versus functional understanding. Does "adiabatically coupled" inherently require a continuous, gradual taper in the waveguide geometry? Or can the term apply to any coupling configuration — including segmented, stepped, or otherwise non-continuous taper designs — that achieves a low-loss mode transition without excitation of higher-order modes? In other words, is "adiabatic" a descriptor of the structural geometry or a descriptor of the functional result?
Segmented taper designs. Is Tanaka aware of segmented taper structures in the silicon photonics field? Does he consider it technically possible for a segmented taper to achieve adiabatic coupling? Has he encountered any literature, presentations, or commercial products that demonstrate adiabatic mode transitions achieved through segmented or non-continuous taper geometries?
Textbooks, papers, and industry standards. What textbooks, scientific papers, or industry standards informed Tanaka's understanding of the term "adiabatic" as applied to optical waveguide coupling? Did Tanaka rely on any specific references when discussing or defining "adiabatic coupling" with his co-inventors or with OWS's patent prosecution counsel?
3. Anticipated Opposing Counsel Strategy
We anticipate that Lumos's counsel — likely Victoria Ashworth, who is lead BHS partner on the claim construction issues, and potentially Daniel Kowalski, who serves as associate — will seek to elicit testimony from Tanaka that supports Lumos's narrow construction of "adiabatically coupled." Specifically, we expect the following lines of attack:
•  Ashworth will attempt to establish that "adiabatically coupled" was universally understood by those working in the silicon photonics field in 2016–2017 to require a continuous, gradual taper that prevents excitation of higher-order modes "throughout the entire transition region" — language that tracks Lumos's proposed construction.
•  Ashworth may confront Tanaka with textbook definitions or excerpts from academic papers that define "adiabatic" transitions in terms of continuous, gradual changes in waveguide geometry, and will ask Tanaka to agree that these definitions reflect the understanding of a POSITA.
•  Ashworth may attempt to use Tanaka's own '456,012 patent against him by arguing that, if the '456,012 patent describes a non-adiabatic coupling approach, then the addition of "adiabatically coupled" to the '567 Patent claims was specifically intended to exclude all coupling approaches other than those employing continuous tapers.
•  Ashworth may argue that if Tanaka truly understood "adiabatic" coupling to encompass segmented taper designs, there would have been no need to amend the '567 Patent claims to add the "adiabatically coupled" limitation, because the claims would already have been patentable over the '456,012 prior art.
4. Preparation Points
In preparation for the deposition, the following points should be emphasized with Tanaka (to the extent his honest recollection is consistent with these positions):
•  The term "adiabatic" in the silicon photonics field refers to a functional characteristic of the mode transition — specifically, that the transition is sufficiently slow and gradual (in terms of the optical mode profile) that optical power is transferred from one waveguide to another without significant loss and without excitation of higher-order modes. The term describes the result of the coupling, not the specific geometric structure used to achieve it.
•  The amendment adding "adiabatically coupled" during prosecution of the '567 Patent was intended to distinguish the prior art's non-adiabatic (abrupt) coupling approach, rather than to impose a structural limitation requiring a specific taper geometry (e.g., continuous versus segmented). The '456,012 patent employed a coupling mechanism that was fundamentally non-adiabatic in character — for example, butt-coupling or abrupt transitions — and the "adiabatically coupled" limitation was added to distinguish the '567 Patent from that approach.
•  The specification of the '567 Patent describes the invention in terms of functional performance characteristics, including low insertion loss, high coupling efficiency, and minimal higher-order mode excitation. While the specification does describe certain embodiments employing continuous tapers, it does not limit the claimed invention exclusively to such embodiments.
•  A person of ordinary skill in the art, reading the '567 Patent claims in light of the specification and prosecution history, would understand "adiabatically coupled" to refer to the functional performance of the coupling, not to a single permissible structural configuration.
B. "Tapered Silicon Waveguide Having a Tip Width of Less Than 200 Nanometers"
While not the primary disputed term, the dimensional limitation in Claim 1 — "a tip width of less than 200 nanometers" — requires attention during the deposition to establish Tanaka's understanding of its functional significance and its relationship to the overall claim scope.
Tanaka should be asked:
•  What is the functional significance of specifying a sub-200nm tip width for the tapered silicon waveguide? Why was this dimensional threshold chosen?
•  How does the sub-200nm tip width relate to mode matching with the silicon nitride waveguide layer? What is the physical mechanism by which reducing the silicon waveguide tip width to below 200nm facilitates efficient optical coupling?
•  Is the 200nm threshold a precise boundary, or is it an approximate value chosen to define a range in which the desired mode-matching behavior occurs? What happens at tip widths above 200nm? What happens at tip widths well below 200nm?
•  Were there specific simulation results, experimental data, or design considerations at OWS that led to the selection of 200nm as the threshold value?
The purpose of this line of questioning is twofold. First, it establishes the technical record regarding this claim limitation. Second, it provides an opportunity to reinforce the narrative that the '567 Patent claims are defined in terms of functional performance thresholds rather than rigid structural prescriptions — a theme that supports OWS's broader construction of "adiabatically coupled."
C. Other Claim Elements
The remaining claim elements in the asserted claims should also be explored with Tanaka, both to build a complete record and to identify any secondary construction disputes that may arise.
"Silicon nitride waveguide layer." Tanaka should confirm his understanding of this term. Is "silicon nitride" used in its conventional sense (Si₃N₄)? Does "waveguide layer" connote a specific structural configuration (e.g., a planar slab waveguide, a channel waveguide, or a rib waveguide)? Is the term limited to stoichiometric silicon nitride, or does it encompass silicon-rich nitride or other compositional variants?
"Integrated optical coupler." The term "integrated" should be explored. Does it mean that the coupler is monolithically integrated on a single substrate, or can it encompass hybrid integration approaches (e.g., flip-chip bonding or wafer bonding)? Tanaka's understanding of this term may be relevant to the scope of the asserted claims.
Dependent Claims 4, 7, 12, and 15. Each dependent claim adds additional limitations to independent Claim 1. Tanaka should be walked through each of these claims and asked to explain his understanding of the additional limitations, including any specific technical terms or dimensional ranges recited therein. The purpose is to build a record of the inventor's understanding that can be cited in the claim construction briefing and at the Markman hearing.
IV. The Prior Art Patent — U.S. Patent No. 9,456,012 (Tanaka et al.)
Tanaka's '456,012 patent is the single most important prior art reference in this litigation. It was cited by the examiner during prosecution of the '567 Patent and was the basis for the claim narrowing that gave rise to the prosecution history estoppel arguments now being advanced by Lumos. Understanding the content and scope of the '456,012 patent through Tanaka's own testimony is essential to our claim construction strategy.
A. Background and Context
The deposition should establish the following background facts regarding the '456,012 patent:
•  The full title and general subject matter of U.S. Patent No. 9,456,012. Based on its citation in the prosecution history, the patent relates to waveguide coupling structures, but the specific title and abstract should be confirmed through Tanaka's testimony.
•  The patent issued on September 6, 2016. Its effective filing date should be confirmed.
•  Tanaka is a named inventor. The citation references "Tanaka et al.," indicating the presence of one or more co-inventors. The identities of these co-inventors should be confirmed.
•  The '456,012 patent was developed before Tanaka joined OWS. OWS was founded in 2014, and Tanaka joined in 2016. The inventive work underlying the '456,012 patent therefore predates Tanaka's involvement with OWS and was conducted at his prior place of employment.
•  The ownership and assignment history of the '456,012 patent should be established. Who is the current assignee? Was the patent assigned to Tanaka's prior employer pursuant to an invention assignment agreement? Is the assignee a university, a corporation, or another type of entity? Has the patent been subsequently transferred, licensed, or encumbered?
B. Technical Content of the '456,012 Patent
The substantive technical disclosures of the '456,012 patent are critical to the claim construction analysis. Tanaka should be asked to explain the technical content of his own prior art patent in detail, including the following areas:
•  What does the '456,012 patent disclose regarding waveguide coupling? What specific structures, methods, and configurations for coupling light between waveguides are described in the specification and claims?
•  Does the '456,012 patent disclose adiabatic coupling? If so, how does it define, describe, or characterize adiabatic coupling? If not, how does the '456,012 patent characterize the coupling mechanism it discloses?
•  Does the '456,012 patent disclose a tapered silicon waveguide coupler? If so, what taper geometry is described — continuous, segmented, stepped, or otherwise? What are the dimensional parameters of the disclosed taper (e.g., tip width, taper length, taper angle)?
•  Does the '456,012 patent disclose or teach a continuous taper, a segmented taper, both, or neither? This is a critical factual question, as the answer directly impacts the prosecution history estoppel analysis.
•  What are the key structural differences between the coupler described in the '456,012 patent and the coupler claimed in the '567 Patent? Are these differences primarily geometric (e.g., taper shape), material (e.g., different waveguide materials), functional (e.g., different coupling mechanisms or performance characteristics), or some combination?
•  What coupling efficiencies or insertion losses does the '456,012 patent report for its disclosed waveguide coupler? How do these compare to the performance characteristics described in the '567 Patent?
The goal of this line of questioning is to establish, through Tanaka's own testimony, that the coupling mechanism described in the '456,012 patent is fundamentally different in character from the "adiabatic coupling" recited in the '567 Patent claims — not merely different in taper geometry, but different in the underlying physical mechanism of optical mode transition.
C. Distinguishing the '567 Patent from the '456,012 Prior Art
The prosecution history of the '567 Patent reveals that the claims underwent two office action rejections, with the examiner in Art Unit 2828 citing the Tanaka '456,012 patent as anticipatory prior art under 35 U.S.C. § 102(a)(1). In response, the claims were amended to include the "adiabatically coupled" limitation, and the applicant submitted remarks distinguishing the claimed invention from the '456,012 prior art. The claims were subsequently allowed.
Tanaka's understanding of this process is critical, and the following questions should be pursued:
•  Was Tanaka aware during prosecution that his own prior patent was being cited against the '567 Patent application? If so, when and how did he become aware?
•  Did Tanaka participate in any discussions with Ted Marchetti (OWS VP of IP), Dr. Kevin Fong, Dr. Priya Ramanathan, or anyone else regarding the strategy for overcoming the '456,012 prior art rejection?
•  What did Tanaka understand to be the basis for distinguishing the '567 Patent from the '456,012 prior art? Did he understand the distinction to be based on a specific structural feature (e.g., continuous versus non-continuous taper), or on a functional characteristic (e.g., adiabatic versus non-adiabatic mode transition)?
•  Critical question: Did Tanaka understand the addition of the "adiabatically coupled" limitation to be narrowing the '567 Patent claims to cover only continuous taper designs? Or did he understand the amendment to be distinguishing the '567 Patent from the '456,012 prior art on the basis that the '456,012 patent discloses a non-adiabatic coupling approach (e.g., abrupt transitions, butt-coupling, or other coupling mechanisms that do not achieve low-loss mode transition)?
•  Does the '456,012 patent disclose a coupling approach that Tanaka would characterize as "non-adiabatic"? If so, what specific features of the '456,012 patent's coupling mechanism make it non-adiabatic?
If Tanaka testifies that the '456,012 patent discloses a fundamentally non-adiabatic coupling approach — for example, one involving abrupt transitions, butt-coupling, or significant mode mismatch — then the "adiabatically coupled" limitation can be understood as excluding that non-adiabatic approach, rather than as limiting the claims to only one specific type of adiabatic coupling structure (i.e., continuous tapers). This testimony would support OWS's broader construction and help rebut Lumos's prosecution history estoppel arguments.
V. Prosecution History and Estoppel Issues
The prosecution history of the '567 Patent is central to the claim construction dispute, and Lumos has raised prosecution history estoppel as a key defense. This section outlines the deposition questions designed to address these issues through Tanaka's testimony.
A. Prosecution History of the '567 Patent
As noted above, the '567 Patent application underwent two office action rejections during prosecution. The key facts are as follows:
•  The examiner in Art Unit 2828 cited the Tanaka '456,012 patent as prior art under 35 U.S.C. § 102(a)(1) in both office actions.
•  In response to the second (final) office action, the applicant filed a Request for Continued Examination and amended the claims to add the "adiabatically coupled" limitation to Claim 1. The applicant also submitted remarks distinguishing the claimed invention from the '456,012 prior art.
•  The amended claims were subsequently allowed, and the patent issued on March 19, 2019.
Tanaka's involvement in this prosecution process must be established. The following questions should be explored:
•  What representations were made to the USPTO during prosecution regarding the scope and meaning of "adiabatically coupled"? Tanaka should be shown the applicant's remarks submitted in connection with the RCE and asked whether he is familiar with them and whether they accurately reflect his understanding.
•  Did Tanaka participate in any interviews with the examiner? The file history should be reviewed for any record of examiner interviews, and Tanaka should be asked whether he participated in or was present for any such interviews.
•  Did Tanaka provide any declarations or affidavits during prosecution? Under 37 C.F.R. § 1.132, inventor declarations are sometimes submitted to support patentability. Tanaka should be asked whether he provided any such declarations.
•  Ted Marchetti, OWS's VP of IP, handled prosecution of the '567 Patent. Marchetti is a registered patent attorney (Reg. No. 58,304) and a former USPTO examiner in Art Unit 2828 — the same art unit that examined the '567 Patent application. Tanaka should be asked about his interactions with Marchetti during prosecution, including whether Marchetti consulted Tanaka about the claim amendments or the prosecution strategy, and whether Tanaka reviewed any of the prosecution papers before they were filed.
B. Prosecution History Estoppel — Lumos's Arguments
Lumos, through its counsel at BHS, is raising prosecution history estoppel arguments in connection with the '567 Patent. The doctrine of prosecution history estoppel, as articulated by the Federal Circuit in Festo Corp. v. Fenmore & Co., 535 U.S. 722 (2002), and its progeny, provides that when a patentee narrows a claim during prosecution to secure the patent, the patentee may be estopped from later recapturing through the doctrine of equivalents the scope that was surrendered by the narrowing amendment.
Lumos's specific estoppel argument is as follows:
•  The original claims of the '567 Patent application did not include the "adiabatically coupled" limitation.
•  The "adiabatically coupled" limitation was added by amendment in response to the examiner's rejection over the Tanaka '456,012 prior art.
•  Under Festo, this narrowing amendment creates a presumption that the patentee surrendered the territory between the original, broader claim scope and the amended, narrower claim scope.
•  Lumos contends that, by adding the "adiabatically coupled" limitation, OWS surrendered all coupling approaches other than those employing continuous, gradual tapers — the approach that Lumos argues is the only approach properly characterized as "adiabatic."
•  Therefore, Lumos argues, OWS cannot now assert that "adiabatically coupled" covers segmented (non-continuous) taper designs like those used in the LumosBridge and LumosEdge products, because doing so would impermissibly recapture the scope that was surrendered during prosecution.
Tanaka's testimony on the intended scope of the "adiabatically coupled" limitation at the time the amendment was made is critical to rebutting this estoppel argument. The following lines of inquiry should be pursued:
•  What did Tanaka understand the amendment was intended to accomplish? Was it directed at excluding a specific structural configuration (i.e., non-continuous tapers), or was it directed at excluding a specific type of coupling mechanism (i.e., non-adiabatic coupling approaches such as butt-coupling or abrupt transitions)?
•  If the '456,012 patent describes a coupling approach that is non-adiabatic in character (e.g., butt-coupling, abrupt transitions, or coupling with significant mode mismatch), then the amendment can be understood as directed at excluding that non-adiabatic approach — not at limiting the claims to only continuous taper designs. Under the Festo framework, the presumption of prosecution history estoppel can be rebutted if the narrowing amendment bore no more than a tangential relation to the equivalent in question, or if there were other reasons why the patentee could not reasonably have been expected to have drafted the original claim to cover the equivalent.
•  If Tanaka testifies that the '456,012 patent's coupling mechanism is fundamentally different from adiabatic coupling — not because of the taper geometry, but because of the underlying physical mechanism — then the estoppel argument collapses, because the amendment was not directed at the structural distinction between continuous and segmented tapers.
C. Tanaka's Knowledge of Applicant's Remarks During Prosecution
The applicant's remarks submitted during prosecution of the '567 Patent are part of the intrinsic record that the Court will consider in construing the claims. These remarks — which were drafted and filed by Ted Marchetti on behalf of OWS — contain specific representations about the meaning and scope of the "adiabatically coupled" limitation and the distinctions between the claimed invention and the '456,012 prior art.
The following questions should be put to Tanaka:
•  Has Tanaka reviewed the applicant's remarks submitted in connection with the prosecution of the '567 Patent? If so, when did he first review them?
•  Did Tanaka review or approve any response to the office actions before it was filed with the USPTO?
•  Was Tanaka consulted about the scope of the "adiabatically coupled" limitation before it was added to the claims? If so, by whom, and what was the substance of the consultation?
•  Does Tanaka agree with the representations made in the applicant's remarks regarding the meaning of "adiabatically coupled" and the distinctions between the '567 Patent and the '456,012 prior art?
•  Is there anything in the applicant's remarks that Tanaka believes is inaccurate, misleading, or inconsistent with his own understanding of the invention and the scope of the claims?
The purpose of these questions is to determine the extent to which Tanaka can be associated with — or distanced from — the specific representations made during prosecution. If Tanaka was actively involved in the prosecution process and agreed with the representations made to the USPTO, his testimony will carry greater weight on the estoppel issues. If he was uninvolved and unfamiliar with the prosecution papers, his testimony will be less probative on estoppel but may still be valuable on the broader question of how a POSITA understood the term "adiabatically coupled."
VI. Tanaka's Knowledge of the Accused Lumos Products
While the primary focus of this deposition is claim construction rather than infringement, Tanaka's familiarity with the accused Lumos products and his technical opinions regarding those products may shed light on the scope and meaning of the disputed claim terms. Additionally, establishing Tanaka's knowledge of the accused products during the claim construction deposition may streamline subsequent fact discovery depositions.
A. LumosBridge™ 800G Optical Engine
The LumosBridge™ 800G Optical Engine is one of the two accused products in this litigation. It employs a segmented (non-continuous) taper with discrete coupling sections — a design that Lumos contends falls outside the scope of the "adiabatically coupled" limitation under Lumos's proposed narrow construction.
The following questions should be put to Tanaka:
•  Is Tanaka familiar with Lumos Photonics, Inc. or any of its products?
•  Has Tanaka ever seen, reviewed, or analyzed the LumosBridge 800G Optical Engine or any technical documentation, datasheets, or design files relating to it?
•  Is Tanaka familiar with the segmented taper design approach employed by the LumosBridge? Has he encountered this design approach in his own work or in the literature?
•  Does Tanaka have any knowledge of when the LumosBridge was first shipped to customers (Q1 2022) or its approximate unit price range ($1,200–$1,800)?
B. LumosEdge™ 400ZR+ Pluggable Transceiver
The LumosEdge™ 400ZR+ Pluggable Transceiver is the second accused product. It is a QSFP-DD form factor pluggable transceiver that has been in production since Q3 2021, with a unit price range of approximately $600–$900.
•  Does Tanaka have any knowledge of the LumosEdge 400ZR+ Pluggable Transceiver?
•  Has Tanaka ever reviewed any technical documentation or marketing materials relating to this product?
•  Is Tanaka aware of the coupling architecture employed in the LumosEdge transceiver?
C. Technical Comparison
Regardless of whether Tanaka has specific knowledge of the accused Lumos products, his technical opinion on the broader question of whether a segmented taper design can achieve adiabatic coupling is highly relevant to the claim construction dispute. This line of questioning connects directly to the meaning of "adiabatically coupled" as understood by a POSITA:
•  In Tanaka's technical opinion, can a segmented (non-continuous) taper structure achieve adiabatic coupling, as he understands that term?
•  What physical criteria must a coupling structure satisfy in order for the coupling to be characterized as "adiabatic"? Is continuity of the taper one of those criteria, or is it the rate of change in the effective mode index that determines whether the coupling is adiabatic?
•  If a segmented taper structure achieves the same functional result as a continuous taper — i.e., low-loss mode transition without excitation of higher-order modes — would Tanaka characterize that structure as "adiabatically coupled"?
This testimony is directly relevant to rebutting Lumos's narrow construction. If a named inventor of the '567 Patent and a recognized expert in waveguide coupling would understand segmented taper designs to be capable of achieving "adiabatic coupling," that supports OWS's broader construction and undermines Lumos's argument that "adiabatically coupled" is inherently limited to continuous taper geometries.
VII. State of the Art at the Time of Invention
Establishing the state of the art in silicon photonics waveguide coupling at the time of the '567 Patent invention (circa 2016–2017) is important for claim construction because the meaning of claim terms is assessed from the perspective of a POSITA at the time of the invention. Tanaka, as both a POSITA and a named inventor, is uniquely positioned to provide testimony on this topic.
A. Silicon Photonics Waveguide Coupling — Circa 2016–2017
The following areas should be explored:
•  What was the state of the art in fiber-to-chip and chip-to-chip optical coupling in the 2016–2017 timeframe? What were the principal technical challenges being addressed by researchers and companies working in this area?
•  What coupling approaches were known and in use at that time? These may include, among others, grating couplers, edge couplers, tapered couplers, inverse tapers, segmented couplers, and evanescent coupling approaches. Tanaka should be asked to describe each approach he was aware of and to compare their respective advantages and limitations.
•  How was the term "adiabatic" used in the silicon photonics community at that time? Was it used exclusively to describe coupling through continuous tapers, or was it applied more broadly to any coupling approach that achieved slow, low-loss mode transitions? Were there published papers or textbook treatments that defined "adiabatic coupling" in a way that is relevant to the claim construction dispute?
•  Chen & Liu (2016). Lumos has cited the following publication as prior art against the '567 Patent under 35 U.S.C. § 103: Chen & Liu, "Segmented Taper Coupler Design for Low-Loss Fiber-to-Chip Coupling," Journal of Photonic Integration, Vol. 14, No. 3, pp. 217–229 (2016). This publication discusses segmented taper coupler designs and their performance characteristics. Tanaka should be asked:
•  Was Tanaka aware of the Chen & Liu publication at the time of the '567 Patent invention?
•  Has Tanaka read the Chen & Liu publication? If so, when did he first read it?
•  Does Chen & Liu use the term "adiabatic" in connection with segmented taper designs? If so, how?
•  Does the existence of the Chen & Liu publication support or undermine the proposition that a POSITA in 2016–2017 would have understood "adiabatic coupling" to encompass segmented taper designs?
This last point is significant because Lumos is attempting to use the Chen & Liu reference to serve two seemingly contradictory purposes: (1) as prior art to challenge the validity of the '567 Patent, suggesting that segmented taper couplers were known and obvious; and (2) as evidence that "adiabatically coupled" in the '567 Patent cannot cover segmented taper designs, because segmented tapers were a known, distinct approach that would not have been characterized as "adiabatic." If Chen & Liu uses the term "adiabatic" in connection with segmented tapers, or if Tanaka would characterize the Chen & Liu designs as adiabatic, Lumos's narrow construction is undermined.
B. OWS's Manufacturing Context
The practical manufacturing context in which the '567 Patent invention was developed may inform the claim construction analysis, particularly if manufacturing constraints influenced the scope of the claimed invention. The following areas should be explored:
•  OWS is a fabless semiconductor company. Its photonic integrated circuits are fabricated by Pinnacle Semiconductor Foundry Co., Ltd. on Pinnacle's 45nm silicon-on-insulator ("SOI") process at its fabrication facility in Hsinchu, Taiwan. Tanaka should confirm his familiarity with this manufacturing arrangement.
•  How did the capabilities and limitations of the Pinnacle 45nm SOI process influence the '567 Patent invention? Were there specific design constraints imposed by the foundry process — such as minimum feature sizes, layer thicknesses, etch profiles, or overlay tolerances — that shaped the design of the claimed waveguide coupler?
•  Were there manufacturing considerations that influenced the decision to specify a tip width of "less than 200 nanometers" in Claim 1? Was this threshold chosen based on what was achievable with the Pinnacle 45nm SOI process?
•  Did the Pinnacle process impose any limitations that would favor one type of taper geometry (continuous versus segmented) over another? If so, is that preference reflected in the patent specification or claims?
VIII. Tanaka's Departure from OWS
Tanaka's departure from OWS in 2019 and his current relationship with the company are relevant to assessing his credibility, potential biases, and willingness to cooperate with OWS's litigation efforts. This section outlines the areas of inquiry designed to explore these issues.
A. Circumstances of Departure
•  Tanaka was employed at OWS from approximately 2016 to 2019. The precise dates of his employment should be confirmed.
•  What were the reasons for Tanaka's departure from OWS? Was the departure voluntary (e.g., resignation to pursue another opportunity) or involuntary (e.g., termination, layoff, or constructive discharge)?
•  What is Tanaka's current relationship with OWS? Does he characterize it as cooperative, neutral, or adverse? Has he had any contact with OWS personnel since his departure?
•  Did Tanaka sign a non-compete agreement, a non-solicitation agreement, an invention assignment agreement, or any other restrictive covenant in connection with his employment at OWS? If so, are any of these agreements still in effect?
•  Did Tanaka sign a separation agreement or release in connection with his departure from OWS? If so, does the separation agreement contain any provisions regarding cooperation with OWS in connection with litigation or patent matters?
B. Potential Bias or Adverse Interests
Tanaka occupies a unique and potentially complicated position in this litigation. His own prior art patent (U.S. 9,456,012) is being used by Lumos to attack a patent (the '567 Patent) that Tanaka himself co-invented. This creates a situation in which Tanaka may have divided loyalties or mixed incentives:
•  On the one hand, Tanaka has an interest as a co-inventor in defending the validity of the '567 Patent and supporting a claim construction that preserves the patent's scope. A finding that the '567 Patent is invalid or unenforceable would reflect poorly on Tanaka's inventive contribution.
•  On the other hand, Tanaka may feel vindicated if his prior art patent is recognized as foundational, and he may be reluctant to minimize the significance of the '456,012 patent in order to distinguish the '567 Patent.
•  Additionally, if Tanaka departed OWS under adverse circumstances, he may be inclined — consciously or unconsciously — to provide testimony that harms OWS's litigation position.
The following specific areas should be explored to assess potential bias:
•  Has Tanaka been contacted by Lumos Photonics, Inc. or by anyone acting on Lumos's behalf, including any attorney at Brannick Howell & Stein LLP, in advance of the deposition or at any time since the commencement of this litigation?
•  Has Tanaka been contacted by Dr. Raymond Ng (BHS Of Counsel / Technical Consultant and former professor of photonics at the University of Colorado Boulder)? Does Tanaka have any pre-existing relationship with Dr. Ng?
•  Does Tanaka have any financial interest in the outcome of this litigation? For example, does Tanaka hold any equity, stock options, or other financial interests in OWS or Lumos? Is Tanaka entitled to any royalties, bonuses, or other compensation tied to the '567 Patent or the '456,012 patent?
•  Has Tanaka entered into any agreement or understanding with any party regarding the substance of his deposition testimony?
C. Cooperation and Preparation
Tanaka is a former employee of OWS and is not currently represented by OWS's counsel. His cooperation with OWS's litigation efforts cannot be assumed and must be assessed.
•  Has Tanaka agreed to appear voluntarily for the deposition, or will a subpoena be required? If a subpoena is necessary, we will need to confirm that Tanaka is within the geographic scope of the subpoena power of the Northern District of California or make alternative arrangements. Federal Rule of Civil Procedure 45 limits the geographic reach of subpoenas for deposition testimony, and if Tanaka resides outside the Northern District, a commission or letters rogatory may be needed.
•  A pre-deposition preparation session with Tanaka is essential to understand his current positions on the key issues and to identify any areas in which he may provide adverse testimony. This preparation session should be conducted by Alan Ngo and/or Omar Siddiqui sufficiently in advance of the deposition date to allow time for follow-up review of documents and adjustment of strategy.
•  If Tanaka refuses to participate in a pre-deposition preparation session, we will need to proceed with the deposition without the benefit of advance knowledge of his positions, which significantly increases the risk of adverse testimony.
•  If Tanaka is cooperative, we should consider whether OWS should retain him as a consultant or fact witness for the Markman hearing, subject to conflict-of-interest analysis and approval by OWS management.
IX. Anticipated Cross-Examination Topics by Lumos's Counsel
This section outlines the lines of questioning we anticipate from Lumos's counsel at BHS and provides preparation points designed to equip Tanaka to respond effectively while maintaining consistency with OWS's claim construction positions.
A. Expected Approach by Victoria Ashworth / Daniel Kowalski (BHS)
Victoria Ashworth is the lead partner at BHS responsible for the claim construction phase of this litigation. She is known for aggressive and highly prepared Markman briefing and has a track record of effectively leveraging inventor depositions to support narrow claim constructions. Daniel Kowalski, a mid-level associate, typically assists Ashworth with deposition questioning and may handle certain technical lines of inquiry. Dr. Raymond Ng, BHS's Of Counsel and technical consultant, is a former professor of photonics at the University of Colorado Boulder and may attend the deposition in a consulting capacity, providing real-time technical guidance to Ashworth and Kowalski.
We anticipate the following principal lines of questioning from Lumos's counsel:
Line 1: The "adiabatically coupled" amendment was directed at continuous taper geometry. Ashworth will seek testimony that the "adiabatically coupled" limitation was added specifically to distinguish the '567 Patent from the '456,012 prior art, and that this distinction necessarily limits the '567 Patent claims to continuous taper designs. She will attempt to establish that the only structural difference between the '456,012 patent and the '567 Patent is the presence of a continuous (as opposed to non-continuous) taper, and that the "adiabatically coupled" limitation was therefore intended to capture that specific structural distinction.
Line 2: Tanaka understood "adiabatic" to require a gradual, continuous transition. Ashworth will present Tanaka with textbook definitions, academic papers, and other references that define "adiabatic" transitions in terms of continuous, gradual changes in waveguide geometry. She will ask Tanaka to confirm that these definitions reflect how a POSITA in 2016–2017 would have understood the term. She may also ask Tanaka how he used the term "adiabatic" in his own prior publications and patents, looking for any instance in which Tanaka equated "adiabatic" with "continuous."
Line 3: The '567 Patent claims were deliberately narrowed and cannot be read broadly. Ashworth will argue that the prosecution history demonstrates a clear intent to narrow the claims, and that OWS cannot now seek a broader construction than what was represented to the USPTO. She will ask Tanaka whether he understood the amendment to be narrowing the claims, and whether he agreed with the narrowing.
Line 4: Chen & Liu (2016) demonstrates that segmented tapers were known but not considered "adiabatic." Ashworth may attempt to use the Chen & Liu publication to establish that segmented taper designs were a known, distinct category of coupling technology in 2016, and that the silicon photonics community did not consider segmented taper coupling to be "adiabatic" coupling. She may point to specific language in the Chen & Liu paper that distinguishes segmented taper couplers from adiabatic couplers, and will ask Tanaka to confirm that this distinction was understood in the field.
B. Preparation Points for Tanaka
In preparing Tanaka for the deposition, the following key points should be emphasized. These are not scripted answers, and Tanaka should testify truthfully based on his own knowledge and recollection. However, to the extent his honest recollection is consistent with these positions, they should be reinforced during the preparation session.
Point 1: "Adiabatic" refers to a functional characteristic. The term "adiabatic" as used in the silicon photonics field refers to a functional characteristic of the optical mode transition — specifically, that the transition occurs slowly enough relative to the coupling length that optical power is transferred from one waveguide mode to another without significant loss and without excitation of higher-order modes. The term describes the quality of the mode transition, not the specific geometric structure used to achieve it. A continuous taper is one way to achieve adiabatic coupling, but it is not the only way.
Point 2: The amendment was directed at the prior art's non-adiabatic coupling mechanism. The amendment adding "adiabatically coupled" during prosecution of the '567 Patent was intended to distinguish the '456,012 prior art's coupling mechanism, which was non-adiabatic in character (e.g., butt-coupling, abrupt transitions, or coupling with significant mode mismatch). The amendment was not intended to impose a structural limitation requiring a continuous taper geometry to the exclusion of all other geometries that could achieve adiabatic coupling.
Point 3: The specification supports a functional understanding. The specification of the '567 Patent describes the invention in terms of its functional performance characteristics — low insertion loss, high coupling efficiency, and minimal higher-order mode excitation — rather than exclusively in terms of continuous taper geometry. While the specification does describe certain embodiments employing continuous tapers, it also describes the invention in broader functional terms that are consistent with OWS's proposed construction.
Point 4: The '234 Patent specification provides context. While Tanaka is not a named inventor on U.S. Patent No. 10,567,234 (the "'234 Patent"), which is also asserted in this litigation, the specification of the '234 Patent contains embodiment descriptions that may inform a POSITA's understanding of the key terms at issue in the '567 Patent. To the extent Tanaka is familiar with the '234 Patent, his testimony on the consistency of terminology across the OWS patent portfolio may be useful.
X. Documents to Be Reviewed with Witness Pre-Deposition
The following documents should be reviewed with Tanaka during the pre-deposition preparation session. This review serves the dual purpose of refreshing Tanaka's recollection regarding the relevant events and technical subject matter, and enabling counsel to assess the likely substance and tone of Tanaka's deposition testimony.
1.  U.S. Patent No. 10,234,567 (the '567 Patent) — full specification, drawings, and claims, with particular attention to the description of the claimed waveguide coupler and the use of the term "adiabatically coupled" in the specification and claims.
2.  U.S. Patent No. 9,456,012 (Tanaka prior art patent) — full specification, drawings, and claims, with particular attention to the disclosure of waveguide coupling structures and any use of the term "adiabatic" or related terminology.
3.  File History of U.S. Patent No. 10,234,567 — complete file wrapper, including all office actions, amendments, applicant remarks, examiner interviews (if any), and the Notice of Allowance. Particular attention should be paid to the applicant's remarks submitted in connection with the Response to the Final Office Action and the RCE, which contain the representations regarding the "adiabatically coupled" limitation that are at the center of the prosecution history estoppel dispute.
4.  Chen & Liu, "Segmented Taper Coupler Design for Low-Loss Fiber-to-Chip Coupling," Journal of Photonic Integration, Vol. 14, No. 3, pp. 217–229 (2016) — the prior art publication cited by Lumos under § 103. Tanaka should be asked whether he was familiar with this publication at the time of the invention and whether he agrees or disagrees with its characterization of segmented taper couplers.
5.  OWS's Preliminary Claim Construction Contentions (served September 12, 2022) — to ensure Tanaka is aware of OWS's proposed constructions and the bases therefor.
6.  OWS's Responsive Claim Construction Contentions (served October 3, 2022) — to ensure Tanaka is aware of any refinements or modifications to OWS's positions.
7.  Joint Claim Construction and Prehearing Statement (filed October 14, 2022) — to ensure Tanaka is aware of the agreed-upon and disputed claim terms, the parties' competing proposed constructions, and the intrinsic and extrinsic evidence each party intends to rely upon.
8.  Laboratory notebooks, design files, and internal OWS memoranda reflecting Tanaka's contributions to the '567 Patent invention — to the extent such documents have been identified and produced in discovery. These documents will be essential for establishing th