Contract analysis

I. INTRODUCTION AND PURPOSE OF DECLARATION

1. I, Dr. Harold Whitfield, Ph.D., submit this declaration in support of Plaintiff Optiwave Semiconductor Corp.'s ("OWS") Opening Claim Construction Brief. I have been retained by Calderwood & Harkness LLP, counsel for OWS, to provide expert technical opinions regarding the construction of disputed claim terms in U.S. Patent Nos. 10,234,567 ("the '567 Patent"); 10,891,234 ("the '234 Patent"); 11,045,678 ("the '678 Pa

2. The purpose of this declaration is to opine on the understanding of a person of ordinary skill in the art ("POSITA") with respect to the eleven (11) disputed claim terms identified in the Joint Claim Construction and Prehearing Statement filed on October 14, 2022, pursuant to Patent Local Rule 4-3. My opinions address the plain and ordinary meaning of those disputed terms as a POSITA would have understood them as

3. This declaration is offered in support of OWS's Opening Claim Construction Brief filed on December 5, 2022.

4. In forming the opinions set forth in this declaration, I have drawn upon my extensive education, research, and consulting experience in the field of integrated silicon photonics, spanning more than thirty-five years. I have reviewed the patents-in-suit, their complete prosecution histories, relevant prior art, technical literature, deposition transcripts, and other materials described in Section IV below and liste

5. I am being compensated for my time in connection with this matter at my standard consulting rate, as described further below. My compensation is in no way contingent on the outcome of this litigation or the opinions I express herein.

6. I reserve the right to supplement or amend this declaration as additional information becomes available, including but not limited to responsive expert reports, additional deposition testimony, and any supplemental materials produced by either party.

II. QUALIFICATIONS AND BACKGROUND A. Education

7. I received my Ph.D. in Electrical Engineering from the University of California, Berkeley, in 1987. My doctoral research focused on integrated photonic circuits, and my dissertation, entitled "Coupled-Mode Analysis and Design of Vertically Integrated III-V/Silicon Waveguide Structures for Monolithic Optoelectronic Receivers," addressed the theoretical and experimental aspects of integrating compound semiconductor

8. Prior to my doctoral studies, I received a Master of Science degree in Electrical Engineering from the Massachusetts Institute of Technology in 1983, where my master's thesis focused on the design and characterization of directional coupler structures in lithium niobate for optical switching applications. I received my Bachelor of Science degree in Electrical Engineering, summa cum laude, from the Georgia Institut

9. I am Professor Emeritus in the Department of Electrical and Computer Engineering at the University of California, Santa Barbara ("UCSB"), where I served on the faculty from 1988 until my retirement from active teaching in 2019. During my tenure at UCSB, I held the endowed William S. Friedman Chair in Photonic Engineering from 2004 through 2019.

10. My academic career spans more than three decades of research and teaching in the fields of integrated photonics, silicon photonics, optoelectronic device design, and high-speed optical communication systems. At UCSB, I directed the Integrated Photonics Research Laboratory, where my research group conducted pioneering work on waveguide coupling structures, germanium-on-silicon photodetectors, silicon optical modul

11. Over the course of my academic career, I supervised twenty-seven doctoral dissertations and forty-one master's theses, the majority of which addressed topics directly relevant to the technologies at issue in this litigation. I taught graduate-level courses in "Silicon Photonics" (ECE 245), "Optoelectronic Devices and Systems" (ECE 230), "Guided-Wave Optics" (ECE 228), and "Advanced Semiconductor Device Physics" (

12. I held visiting professorships at Imperial College London (2002–2003) and the Technical University of Denmark (2010), where I collaborated on research programs in photonic integrated circuits and high-speed optical interconnects. C. Professional Affiliations and Recognition

13. Over the course of my career, I have authored or co-authored more than two hundred (200) publications in peer-reviewed journals and conference proceedings in the field of integrated photonics. These publications address a wide range of topics directly relevant to the patents-in-suit, including: (a) waveguide coupling and mode conversion, including taper design, adiabatic transitions, and fiber-to-chip coupling ef

14. Representative publications of direct relevance to the subject matter of this declaration include: • H. Whitfield, J.R. Kowalski, and M.A. Torres, "Adiabatic Mode Conversion in Vertically Coupled Silicon-Silicon Nitride Waveguide Structures," Journal of Lightwave Technology, Vol. 28, No. 14, pp. 2045–2055 (2010). • H. Whitfield and S. Bhargava, "Design Optimization of Inverse Taper Couplers for Low-Loss Fiber-to-

15. I am a Fellow of the Institute of Electrical and Electronics Engineers ("IEEE"), elected in 2007 "for contributions to integrated photonic circuit design and silicon photonics." I am also a Fellow of Optica (formerly the Optical Society of America, or "OSA"), elected in 2005. I am a Senior Member of the International Society for Optics and Photonics ("SPIE").

16. I have received multiple awards for my research contributions, including the IEEE Photonics Society Engineering Achievement Award (2015), the Optica Joseph Fraunhofer Award/Robert M. Burley Prize (2012), and the UCSB Academic Senate Distinguished Teaching Award (2009).

17. I have served on the editorial boards of the Journal of Lightwave Technology, IEEE Photonics Technology Letters, and Optics Express. I have served as a technical program committee member or chair for numerous international conferences, including the Optical Fiber Communication Conference (OFC), the Conference on Lasers and Electro-Optics (CLEO), and the IEEE International Conference on Group IV Photonics. D. Curr

18. Since my retirement from UCSB in 2019, I have been the Principal of Whitfield Technical Consulting Group, Inc., headquartered at 530 Lytton Avenue, Suite 210, Palo Alto, California 94301. Through my consulting practice, I provide technical expert services in patent litigation, technology assessment, and due diligence in the fields of photonics, semiconductors, and optoelectronics. E. Prior Expert Testimony Experi

19. I have been retained as a technical expert in patent litigation matters on numerous occasions. In the past five years, I have been deposed nine (9) times and have provided trial testimony in federal court on four (4) occasions. The subject matters of these prior engagements have included silicon photonics device design, optoelectronic packaging, semiconductor fabrication processes, integrated circuit architecture

20. I am being compensated at the rate of $875 per hour for my consulting and expert services in this matter. This rate is consistent with my standard professional consulting rate. My compensation is not contingent on the outcome of this litigation or on the substance of the opinions I express herein.

III. DEFINITION OF A PERSON OF ORDINARY SKILL IN THE ART

21. The patents-in-suit relate to the field of silicon photonics integrated circuits for high-speed optical communication. Specifically, the claimed inventions address: (a) waveguide coupling structures with tapered mode converters; (b) germanium-on-silicon photodetectors with graded buffer layers; (c) multi-channel optical transceivers with integrated wavelength-division multiplexing; and (d) driver circuit architec

22. Based on my review of the patents-in-suit, the prior art of record, and my experience in the field, I believe that a person of ordinary skill in the art at the time of the inventions would be a person holding at least a Master's degree (or the equivalent) in Electrical Engineering, Applied Physics, or a closely related discipline, with at least three to five (3–5) years of practical experience in the design, fabr

23. Alternatively, a person of ordinary skill in the art could be an individual holding a Ph.D. in Electrical Engineering, Applied Physics, Materials Science, or a related field with at least one to two (1–2) years of industry or academic research experience in silicon photonics.

24. Additional education or training could compensate for less practical experience, and vice versa. The definition I propose is not rigid; individuals with various combinations of education and experience may qualify as persons of ordinary skill in the art.

25. A POSITA at the relevant time would be familiar with standard texts in the field, including works such as Silicon Photonics Design by Chrostowski and Hochberg (Cambridge University Press, 2015), Handbook of Silicon Photonics by Vivien and Pavesi (Aldermere Partners LLC, 2013), and Photonic Devices by Liu (Cambridge University Press, 2005). A POSITA would also be familiar with publications in leading journals such

26. Unless otherwise stated, my opinions in this declaration are offered from the perspective of this defined POSITA.

27. In forming the opinions set forth in this declaration, I have reviewed the documents and materials described below. A complete itemized list is provided in Appendix B. A. Patents-in-Suit

28. I reviewed the following four United States patents that are asserted by OWS in this action: (a) U.S. Patent No. 10,234,567 ("the '567 Patent"), entitled "Integrated Waveguide Coupler with Tapered Mode Converter for Silicon Photonics Platforms," filed March 14, 2017, and issued March 19, 2019. The named inventors are Dr. Kevin Fong, Dr. Priya Ramanathan, and Hideo Tanaka. The '567 Patent contains 20 claims, inclu

29. I reviewed the complete file histories (prosecution histories) for each of the four patents-in-suit, including all office action rejections, applicant responses, claim amendments, examiner interview summaries, requests for continued examination, notices of allowance, and all references cited therein.

30. I paid particular attention to the following prosecution events: (a) The '567 Patent: During prosecution, the Examiner rejected the original claims under 35 U.S.C. § 102(a)(1) as anticipated by Tanaka et al. (U.S. Patent No. 9,456,012, issued September 6, 2016). In a response filed January 22, 2019, the applicants amended independent Claim 1 to add the limitation "adiabatically coupled" and argued that the Tanaka

31. I reviewed the following prior art references that were cited during prosecution or that I otherwise identified as relevant to the claim construction issues in this case: (a) U.S. Patent No. 9,456,012 (Tanaka et al.), issued September 6, 2016, entitled "Optical Waveguide Coupler for Silicon Photonic Devices." This reference was cited against the '567 Patent during prosecution. (b) Chen & Liu, "Segmented Taper Cou

32. I reviewed the following court filings in this action: (a) Joint Claim Construction and Prehearing Statement (Patent L.R. 4-3), filed October 14, 2022. (b) The parties' preliminary claim construction contentions (Patent L.R. 4-1), filed August 12, 2022. (c) Defendant Lumos Photonics, Inc.'s Responsive Claim Construction Contentions (Patent L.R. 4-2), filed September 16, 2022. (d) The Proposed Claim Constructions

33. I reviewed numerous textbooks, journal articles, technical dictionaries, and industry standards relating to silicon photonics, waveguide coupling, germanium photodetectors, wavelength-division multiplexing integration, and modulator driver architectures. The specific references consulted are identified in the body of this declaration where cited and are listed in full in Appendix B. These references include, amon

34. I reviewed publicly available product data sheets and marketing materials for Defendant Lumos Photonics, Inc.'s products, including: (a) Lumos Photonics, Inc., "LumosBridge™ 800G Optical Engine — Product Brief" (Rev. 1.2, June 2022). (b) Lumos Photonics, Inc., "LumosEdge™ 400ZR+ Pluggable Transceiver — Preliminary Data Sheet" (Rev. 0.9, March 2022).

35. I reviewed these materials to understand the accused products in the context of this action and to inform my understanding of how the disputed claim terms relate to real-world commercial implementations, though my opinions in this declaration are directed to claim construction rather than infringement. G. Deposition Transcripts

36. I reviewed the following deposition transcripts: (a) Deposition of Dr. Kevin Fong, taken October 6, 2022. (b) Deposition of Hideo Tanaka, taken October 11, 2022. (c) Deposition of Dr. Amara Osei, taken October 18, 2022.

37. Each of these deponents is a named inventor on one or more of the patents-in-suit. I reviewed their testimony to understand their perspectives on the claimed inventions and the meaning of the claim terms in the context of their work at OWS.

38. Before turning to the disputed claim terms, I provide below an overview of the relevant technology to assist the Court in understanding the context in which the disputed terms are used. This overview is intended to be accessible to a reader who may not have a technical background in silicon photonics, while being consistent with the understanding of a POSITA. A. Silicon Photonics Fundamentals

39. Silicon photonics is a technology platform that uses silicon—the same semiconductor material used in conventional microelectronic chips—as the basis for fabricating photonic (optical) devices. Silicon photonics leverages the mature and cost-effective manufacturing infrastructure of the complementary metal-oxide-semiconductor ("CMOS") fabrication processes used in the microelectronics industry to produce optical c

40. The primary application of silicon photonics is in high-speed optical communication, particularly for data center interconnects and telecommunications networks. As the demand for data bandwidth has grown exponentially—driven by cloud computing, video streaming, artificial intelligence, and other data-intensive applications—the need for high-bandwidth, low-power, and low-cost optical transceivers has become critic

41. A silicon photonic integrated circuit ("PIC") typically comprises several key functional components, each of which plays a distinct role in the optical communication link: (a) Waveguides: Optical waveguides are the "wires" of a photonic circuit, guiding light from one point to another on the chip. In silicon photonics, waveguides are typically formed from a silicon core surrounded by a silicon dioxide (SiO₂) clad

42. OWS is a fabless silicon photonics design company that designs photonic integrated circuits and outsources fabrication to Pinnacle Semiconductor Foundry Co., Ltd., utilizing a 45-nanometer SOI process. This business model is analogous to the fabless model widely used in the microelectronics industry, where chip designers rely on third-party foundries for manufacturing. The patents-in-suit relate to several of the

43. Efficient coupling of light into and out of a silicon photonic chip is a fundamental requirement for any practical silicon photonics product. The challenge arises because of the mode-field mismatch between the relatively large optical mode of a standard single-mode fiber (approximately 10 μm in diameter) and the tightly confined mode of a submicron silicon waveguide (typically 450–500 nm wide by 220 nm tall). Wit

44. Several approaches to fiber-to-chip coupling have been developed, including grating couplers and edge couplers with tapered mode converters. The '567 Patent is directed to the latter category. In a tapered mode converter, the silicon waveguide is gradually tapered to a very narrow tip (often less than 200 nm wide), at which point the optical mode is no longer well-confined by the narrow silicon core and expands i

45. The concept of "adiabatic" mode conversion is central to the '567 Patent and to one of the key disputed claim terms. In the context of waveguide optics, an adiabatic transition is one in which the waveguide geometry changes sufficiently slowly along the propagation direction that the optical mode adapts continuously to the local waveguide geometry at each point along the transition. In an ideal adiabatic transiti

46. The term "adiabatic" in this context is borrowed from thermodynamics and quantum mechanics, where an adiabatic process is one that occurs sufficiently slowly that the system remains in its instantaneous eigenstate at all times. In waveguide optics, the analogous concept is that the transition is sufficiently gradual that the optical field remains in the fundamental mode (the lowest-order eigenstate of the wavegui

47. In contrast, a non-adiabatic transition is one in which the waveguide geometry changes abruptly or too rapidly, causing the optical mode to be scattered into higher-order modes or radiation modes, resulting in optical power loss. An abrupt butt-coupled junction between two dissimilar waveguides is a quintessential example of a non-adiabatic transition.

48. Whether a particular taper qualifies as "adiabatic" depends on the relationship between the taper length, the taper geometry, and the beat length between the fundamental mode and the nearest higher-order mode (or radiation mode) at each point along the taper. As a general rule, a longer taper relative to the beat length will be more adiabatic. Various taper geometries can achieve adiabatic operation, including li

49. The '567 Patent discloses and claims an integrated waveguide coupler employing a tapered silicon waveguide with a tip width of less than 200 nm that is adiabatically coupled to a silicon nitride waveguide layer, achieving efficient mode transfer for fiber-to-chip or layer-to-layer coupling. C. Germanium-on-Silicon Photodetectors

50. As noted above, silicon is transparent at the near-infrared wavelengths commonly used in optical communications (1310 nm and 1550 nm), meaning silicon alone cannot efficiently absorb light at these wavelengths for photodetection. Germanium, by contrast, has a narrower bandgap and can absorb light at these wavelengths. For this reason, germanium-on-silicon (Ge-on-Si) photodetectors are the standard approach for on

51. A significant challenge in growing germanium on silicon is the approximately 4.2% lattice mismatch between the two materials. When germanium is deposited directly on silicon, this lattice mismatch generates a high density of crystallographic defects (threading dislocations) that propagate into the germanium absorber layer and degrade device performance by increasing dark current and reducing responsivity.

52. To mitigate this problem, buffer layers are commonly interposed between the silicon substrate and the germanium absorber. The purpose of the buffer layer is to gradually accommodate the lattice mismatch, reducing the density of threading dislocations that reach the active absorber layer. Two principal approaches to buffer layer design are: (a) Continuously graded buffer layers: In this approach, the composition o

53. Both continuously graded and step-graded buffer layers are well-established in the literature and in commercial practice for SiGe-based devices. The '234 Patent discloses a germanium-on-silicon photodetector architecture employing a graded buffer layer for enhanced responsivity, and one of the disputed claim terms concerns the meaning of "graded buffer layer having a continuously varying germanium concentration."

54. Wavelength-division multiplexing ("WDM") is a technique that increases the data capacity of an optical link by simultaneously transmitting multiple independent data channels, each at a different optical wavelength (color of light), through a single optical waveguide or fiber. At the transmitter, a multiplexer combines the different wavelength channels onto a common output; at the receiver, a demultiplexer separat

55. In silicon photonics, WDM elements can be fabricated using several techniques: (a) Monolithic integration: The WDM element is fabricated as part of the same semiconductor fabrication process on the same silicon die as the other photonic components. Common monolithically integrated WDM structures include arrayed waveguide gratings ("AWGs"), echelle gratings, and cascaded ring resonator filters—all of which can be