PRIVILEGED AND CONFIDENTIAL — ATTORNEY-CLIENT COMMUNICATION / ATTORNEY WORK PRODUCT This memorandum is a privileged and confidential communication prepared by outside counsel Calderwood & Harkness LLP and is protected by the attorney-client privilege and the attorney work-product doctrine. This memorandum is intended solely for the use of Optiwave Semiconductor Corp. and its authorized representatives. Any unauthorized disclosure, distribution, or copying of this memorandum or its contents is strictly prohibited. If you have received this document in error, please notify the sender immediately and destroy all copies.
CALDERWOOD & HARKNESS LLP 555 California Street, 42nd Floor San Francisco, California 94104
MEMORANDUM
March 28, 2022
FROM: Catherine Bloom, Partner, intellectual Property Group (USPTO Reg. No. 58,412), and Christy Bauer, Associate, intellectual Property Group (USPTO Reg. No. 74,329), Calderwood & Harkness LLP, 555 California Street, 42nd Floor, San Francisco, CA 94104
TO: Sandra Koh, IP Manager / In-House Patent Counsel, and Dr. Lena Strickland, VP Engineering, Optiwave Semiconductor Corp., 4710 Ridgeview Parkway, Suite 300, Santa Clara, CA 95054
RE: Patent Prosecution Strategy — Multi-Channel Silicon-Photonic Mach-Zehnder Modulator Application Family
C&H Matter No.: 1014-00005
cc: Marcus Whitfield, General Counsel, Optiwave Semiconductor Corp.; Alan Ngo, Billing Partner, Calderwood & Harkness LLP; Peter Vassiliev, Working Associate, Calderwood & Harkness LLP (for information)
Right-click to update Table of Contents
I. Executive Summary
The purpose of this memorandum is to set forth the comprehensive prosecution strategy for a planned family of twelve (12) related U.S. and international patent applications covering Optiwave Semiconductor Corp.'s ("OWS" or the "Company") next-generation silicon-photonics modulator architecture. This memorandum addresses every aspect of the planned prosecution campaign, including application structure, claim differentiation strategy, filing timelines, international filing strategy, coordination with foreign associates, budget estimates, and risk factors, and is intended to serve as the definitive roadmap for the prosecution program through mid-2026.
All applications in the planned family will ultimately claim priority to U.S. Provisional Application No. 63/297,841, filed January 10, 2022 by OWS's prior outside patent counsel, Kessler & Morin LLP (Dr. Helen Kessler, lead partner), titled "Multi-Channel Silicon-Photonic Mach-Zehnder Modulator with Segmented Traveling-Wave Electrode Architecture." The provisional was filed in the names of Dr. Rajan Menon, Dr. Lena Strickland, Dr. Feng-Yi Chen, and Dr. Arjun Dasgupta as named inventors. The provisional's 12-month statutory term under 35 U.S.C. § 111(b) expires on January 10, 2023. Accordingly, all priority-preserving filings — specifically, at least one non-provisional U.S. application and/or PCT international application — must be made on or before January 9, 2023, the last day on which the January 10, 2022 priority date can be preserved.
The twelve planned applications are organized into three sub-families, each corresponding to a distinct technology cluster within OWS's modulator platform:
(A) Core Modulator Architecture — five planned applications (A1 through A5), encompassing the foundational U.S. non-provisional application, a U.S. continuation, a U.S. continuation-in-part, and two PCT international applications that will serve as the vehicles for European and Japanese national- and regional-phase entries;
(B) Electrode Fabrication Process — four planned applications (B1 through B4), encompassing a U.S. non-provisional directed to fabrication process claims, a U.S. divisional (reserved, to be filed upon receipt of a restriction requirement), and European regional-phase and Japanese national-phase entries derived from PCT Application A4; and
(C) Packaging & Thermal Management — three planned applications (C1 through C3), encompassing a standalone U.S. non-provisional directed to advanced packaging and thermal-management innovations, and European regional-phase and Japanese national-phase entries derived from PCT Application A5.
The key strategic objective underlying the entire prosecution program is to build a robust defensive patent position around OWS's proprietary tapered impedance-matching design-around features. This objective is driven by the need to mitigate infringement risk arising from Pinnacle Optics, Inc.'s blocking patent family, which consists principally of U.S. Patent No. 10,823,417 (issued November 3, 2020) and U.S. Patent No. 11,105,662 (issued August 31, 2021). As discussed in greater detail in Section IV below, Pinnacle's patents claim a silicon-photonic Mach-Zehnder modulator with a uniform segmented traveling-wave electrode geometry. OWS's core innovation — a tapered impedance-matching traveling-wave electrode architecture — represents the principal design-around to Pinnacle's electrode-segmentation geometry, and the planned application family is designed in significant part to capture this feature across multiple claim formats (apparatus, process, and system/packaging claims) and in multiple jurisdictions.
OWS's existing patent portfolio comprises 31 issued U.S. utility patents, all of which were previously prosecuted by Kessler & Morin LLP. The Calderwood & Harkness LLP ("C&H") engagement was opened on February 14, 2022, pursuant to an engagement letter executed on February 10, 2022, which was countersigned by Marcus Whitfield, OWS's General Counsel. C&H has received complete file transfers from Kessler & Morin for all relevant prosecution histories and has undertaken a thorough review of the provisional specification for continuity-of-disclosure purposes.
The named inventors common to most applications in the planned family are Dr. Rajan Menon (CEO), Dr. Lena Strickland (VP Engineering), Dr. Feng-Yi Chen (Principal Engineer), and Dr. Arjun Dasgupta (Senior Design Engineer). Additional inventors may be identified and added as ongoing R&D generates further contributions, particularly in connection with Application A3 (the planned continuation-in-part).
The prosecution strategy encompasses U.S. prosecution before the United States Patent and Trademark Office ("USPTO"), PCT international filings through the World intellectual Property Organization ("WIPO") with the USPTO serving as Receiving Office, European regional-phase entries at the European Patent Office ("EPO") through the firm of Breitenfeld & Vogt Patentanwälte PartGmbB in Munich, Germany, and Japanese national-phase entries at the Japan Patent Office ("JPO") through Nakashima & Togawa Patent Professional Corporation in Tokyo, Japan. Additional national-phase entries in South Korea and China are under consideration but have been deferred pending commercial developments and budget availability.
We respectfully request that OWS management review this memorandum and provide authorization to proceed with the full prosecution program, together with confirmation of budget allocation through mid-2026, at the earliest practicable date.
II. Background
A. Company Overview
Optiwave Semiconductor Corp. is a Delaware corporation, incorporated on April 12, 2017 (Delaware Secretary of State File No. 7284931; California Secretary of State Entity No. C4195872; Federal Employer Identification Number 83-2947105). The Company is headquartered at 4710 Ridgeview Parkway, Suite 300, Santa Clara, California 95054.
OWS is a fabless semiconductor design company specializing in the design and commercialization of silicon-photonics integrated circuits for 800G and 1.6T data-center optical transceivers. The Company's products are principally sold to leading optical transceiver module manufacturers for deployment in hyperscale data centers and telecommunications infrastructure. OWS currently employs approximately 185 individuals, the majority of whom are engineers and technical staff engaged in silicon-photonics design, simulation, and characterization activities at the Company's Santa Clara headquarters and at its design center in Austin, Texas.
For fiscal year 2022, OWS anticipates revenue of approximately $68.1 million, representing continued growth from fiscal year 2021. The Company's chief executive officer is Dr. Rajan Menon, who is also a named inventor on the planned application family. The chief financial officer is Daniel Everhart.
OWS is majority-owned by Harborview Partners, a technology-focused private equity firm. Veltrano acquired a 72% equity stake in OWS in 2019 through a leveraged recapitalization valued at approximately $310 million in enterprise value. The Managing Partner of Veltrano Capital Partners is Theodore "Ted" Hargrove, and the Operating Partner (Technology) is Christine Paulsen. Veltrano's investment thesis for OWS is centered on the Company's proprietary silicon-photonics technology platform and its associated intellectual property portfolio, and accordingly, the strength and scope of the patent portfolio is a matter of significant importance to the Company's principal equity holder. As discussed in Section II.E below, Veltrano has indicated that it may retain an independent IP valuation firm in connection with potential refinancing activity.
B. Engagement Transition from Prior Counsel
OWS was previously represented in all patent prosecution matters by Kessler & Morin LLP, an intellectual property boutique firm based in McLean, Virginia. The lead partner at Kessler & Morin responsible for the OWS engagement was Dr. Helen Kessler, who has extensive experience in semiconductor and photonics patent prosecution. Kessler & Morin represented OWS from the Company's inception in 2017 through the end of 2021, and during that period prosecuted OWS's existing portfolio of 31 issued U.S. utility patents.
Notably, Kessler & Morin filed the provisional application that serves as the priority document for the entire planned application family — U.S. Provisional Application No. 63/297,841, titled "Multi-Channel Silicon-Photonic Mach-Zehnder Modulator with Segmented Traveling-Wave Electrode Architecture" — on January 10, 2022, shortly before the engagement transitioned to C&H. The provisional was filed with a comprehensive specification, including detailed descriptions of the core modulator architecture, electrode fabrication processes, packaging concepts, and thermal-management approaches, together with approximately 28 figures and a set of representative claims. The provisional does not, by itself, undergo substantive examination, but it establishes the priority date for all subsequently filed applications that claim its benefit.
C&H has received complete file transfers from Kessler & Morin for all relevant prosecution histories, including the provisional application file, all 31 issued patent files, and associated inventor declarations, assignment documents, and correspondence. The file transfer was completed on March 8, 2022. C&H has verified the completeness of the transferred files against the portfolio list provided by Sandra Koh. We note that certain continuation applications in the planned docket will claim priority through chains that include K&M-drafted parent applications and the K&M-drafted provisional specification, and accordingly, C&H has reviewed and will continue to review the provisional specification in detail for continuity-of-disclosure purposes, including assessment of written-description support and enablement under 35 U.S.C. §§ 112(a) and (b).
C. Competitive Landscape — Pinnacle Optics blocking Patents
Pinnacle Optics, Inc. is OWS's primary competitor in the silicon-photonics modulator space. Pinnacle is a Delaware corporation with its principal place of business at 7200 Gateway Boulevard, Newark, California 94560. The Vice President of intellectual Property at Pinnacle is Howard Raines. Pinnacle's outside patent counsel is Cavanaugh Holt & Sayer LLP, a prominent intellectual property litigation and prosecution firm based in Washington, D.C., with Grant Sayer serving as lead partner on the Pinnacle engagement. Cavanaugh Holt & Sayer is known for its aggressive prosecution and enforcement strategies in the semiconductor and photonics sectors.
Pinnacle holds two key U.S. patents that are directly relevant to OWS's commercial products and to the prosecution strategy outlined in this memorandum:
U.S. Patent No. 10,823,417 — Issued November 3, 2020. This patent is directed to a silicon-photonic Mach-Zehnder modulator employing a segmented traveling-wave electrode architecture. The independent claims recite, among other elements, a silicon-photonic modulator with a plurality of electrode segments arranged along an optical waveguide, each segment having a substantially uniform impedance-matching characteristic. The '417 patent was filed as U.S. Application No. 16/345,892 and claims priority to a provisional application filed in 2018. The patent lists Howard Raines, Dr. Samuel Kuo, and Dr. Maria Andersen as named inventors.
U.S. Patent No. 11,105,662 — Issued August 31, 2021. This patent is a continuation of the '417 patent and contains narrower but related claims focused on specific electrode-segment spacing parameters and impedance characteristics. In particular, certain dependent claims of the '662 patent recite numerical ranges for segment spacing and impedance ratios that overlap with parameters used in OWS's first-generation modulator products.
Together, these two Pinnacle patents create a potential blocking position against OWS's commercial products, particularly OWS's current-generation modulator integrated circuits that employ a segmented traveling-wave electrode design. The blocking risk arises because OWS's first-generation commercial products were designed before OWS's engineering team developed the tapered impedance-matching feature that is the subject of the pending application family.
C&H is concurrently preparing a detailed freedom-to-operate ("FTO") analysis assessing OWS's exposure to Pinnacle's patent claims. The FTO analysis is expected to be delivered in the third quarter of 2022, with a target delivery date of October 14, 2022. Based on our preliminary assessment, there is a moderate-to-high risk of infringement of the Pinnacle '417 and '662 patents by OWS's first-generation commercial products absent the incorporation of design-around features. The pending application family is designed in significant part to capture OWS's proprietary tapered impedance-matching feature, which represents the principal design-around to Pinnacle's uniform electrode-segmentation geometry. By building a robust patent position around this design-around feature, OWS will not only reduce its own infringement exposure but also establish a defensive portfolio that may deter Pinnacle from initiating enforcement actions and that may serve as a basis for cross-licensing negotiations if necessary.
We also note that Pinnacle is known to be actively prosecuting additional continuation applications in its own modulator patent family. C&H will monitor Pinnacle's published applications and issued patents through the USPTO Patent Application Information Retrieval (PAIR) system and through commercial patent monitoring services, and will adjust OWS's claim strategy as needed to maintain differentiation from Pinnacle's evolving claim scope.
D. IP Collateral Considerations
OWS maintains a $55 million senior secured revolving credit facility (the "Credit Facility") with Meridian National Bank, N.A. ("Meridian"), headquartered at 600 Travis Street, Houston, Texas 77002. The relationship manager at Meridian for the OWS account is Brian Hartwell. The Credit Facility was originally dated September 30, 2020 and was recently amended and restated on March 15, 2022 (the "Amended and Restated Credit Agreement").
The Amended and Restated Credit Agreement contains significant intellectual property covenants. In particular, Section 5.15 (Intellectual Property Covenants) requires OWS to "maintain, preserve, and protect all Material intellectual Property, including by timely prosecuting all pending patent applications and paying all required maintenance fees." This covenant is an affirmative covenant, breach of which would constitute an Event of Default under the Credit Facility (subject to any applicable cure periods specified in Section 8.01 of the Amended and Restated Credit Agreement).
The term "Material intellectual Property" is defined in Section 1.01 of the Amended and Restated Credit Agreement to include "all patents and patent applications listed on Schedule 5.15(a), as updated from time to time." Schedule 5.15(a) was most recently updated as of March 15, 2022 in connection with the amendment and restatement, and currently lists all 31 of OWS's issued U.S. utility patents and the provisional application, U.S. Provisional Application No. 63/297,841.
In addition, the Security Agreement (set forth as Exhibit C to the Amended and Restated Credit Agreement) grants Meridian a first-priority security interest in all "Intellectual Property Collateral," which is broadly defined to include "all patents, patent applications, and patent rights, whether now existing or hereafter acquired or arising." This definition is drafted to capture after-acquired intellectual property, meaning that any new patent applications filed by OWS — including all twelve applications in the planned family — will automatically fall within the scope of the security interest upon filing.
The practical implications of these provisions are twofold. First, prosecution of the planned application family is not only strategically important from a competitive and portfolio-development perspective, but may also be contractually required under the Credit Facility's covenant package, insofar as the planned applications will become "Material intellectual Property" listed on Schedule 5.15(a). Failure to prosecute the applications diligently could, in theory, give rise to a covenant breach. Second, as new applications are filed and new patents issued, counsel should periodically coordinate with OWS and Meridian to update Schedule 5.15(a) to reflect the expanded portfolio. We recommend that such updates be made at least semi-annually, or promptly upon the filing of each new application or issuance of each new patent.
Sandra Koh should confer with Marcus Whitfield and Daniel Everhart to ensure that internal processes are in place to (i) promptly notify Meridian's relationship manager of new patent filings and issuances, (ii) deliver updated Schedules 5.15(a) to Meridian in accordance with any notice provisions in the Amended and Restated Credit Agreement, and (iii) confirm that any required UCC financing statement amendments are filed to perfect Meridian's security interest in the new filings.
E. IP Portfolio Valuation Context
In connection with potential refinancing activity, Veltrano Capital Partners has indicated to OWS management that it may retain an independent IP valuation firm to assess the value of OWS's patent portfolio. The timing and scope of any such valuation engagement have not yet been determined, but it is anticipated that any valuation would occur in 2023 or later, after the initial set of applications (A1, A4, A5) has been filed and prosecution is underway.
The strength, breadth, and jurisdictional coverage of the pending application family will be a material factor in any future portfolio valuation. A well-structured and aggressively prosecuted patent portfolio covering OWS's core modulator architecture, fabrication processes, and packaging innovations — particularly one that demonstrates clear differentiation from the closest prior art (including Pinnacle's blocking patents) — will command a higher valuation than a narrower or less strategically cohesive portfolio. This consideration further supports the recommendation to proceed with the full twelve-application prosecution plan and to allocate sufficient resources to ensure high-quality drafting, responsive prosecution, and broad jurisdictional coverage.
III. Application Family Architecture
A. Priority Chain
All twelve applications in the planned family ultimately claim priority, directly or indirectly, to U.S. Provisional Application No. 63/297,841, filed January 10, 2022. The provisional establishes the earliest possible priority date for all subject matter disclosed therein, and is the anchor document upon which the entire prosecution strategy depends.
Under 35 U.S.C. § 119(e), the 12-month statutory term of a provisional application runs from the date of filing, meaning that the provisional's term expires on January 10, 2023. The last day on which a non-provisional U.S. application or a PCT international application may be filed with a valid priority claim to the provisional is therefore January 9, 2023 — the day before the provisional expires. If no priority-preserving filing is made by that date, the priority date will be irrevocably lost, and all subject matter in the provisional will be evaluated against prior art as of its actual (non-provisional or PCT) filing date rather than the January 10, 2022 provisional filing date. The consequences of losing the priority date would be severe, as intervening publications, Pinnacle's patent disclosures, and other prior art that postdates January 10, 2022 could be cited against OWS's claims.
The planned filing of Applications A1 (U.S. non-provisional), A4 (PCT international), and A5 (PCT international) on January 9, 2023 is specifically designed to satisfy this requirement. By filing all three applications on the same date — the last permissible day — OWS ensures that the priority date is preserved while maximizing the time available for specification drafting, claim refinement, and technical review.
The priority chain for the entire application family is set forth graphically in Appendix A to this memorandum. In summary:
• Applications A1, A4, and A5 each directly claim priority to Provisional 63/297,841.
• Application A2 is a continuation of A1 and thus claims priority to the provisional through A1.
• Application A3 is a continuation-in-part of A1 and claims priority to the provisional through A1 for subject matter supported by the provisional specification; new matter added in A3 will have an effective filing date of A3's actual filing date (approximately June 2023).
• Application B1 is a standalone U.S. non-provisional that may claim priority to the provisional directly or through A1, depending on the final claim scope and disclosure strategy; this determination will be made during drafting.
• Application B2 is a divisional of B1.
• Applications B3 and B4 enter the European and Japanese phases, respectively, from PCT Application A4.
• Application C1 is a standalone U.S. non-provisional; it will not claim priority through A1 but may claim priority to the provisional directly, provided its claims are supported by the provisional specification.
• Applications C2 and C3 enter the European and Japanese phases, respectively, from PCT Application A5.
B. Sub-Family A — Core Modulator Architecture (5 Planned Applications)
Sub-Family A comprises the most strategically important applications in the family, as these applications will carry the broadest claims to OWS's core modulator architecture and the tapered impedance-matching traveling-wave electrode feature that is the centerpiece of OWS's design-around strategy.
Application A1 — U.S. Non-Provisional
Filing type: U.S. non-provisional utility application under 35 U.S.C. § 111(a)
Target filing date: January 9, 2023
Application number: To be assigned upon filing (anticipated serial number: 17/672,204, based on current USPTO numbering sequence at time of drafting)
Priority claim: Claims benefit of U.S. Provisional Application No. 63/297,841, filed January 10, 2022, under 35 U.S.C. § 119(e)
Subject matter: Claims directed to the multi-channel silicon-photonic Mach-Zehnder modulator with the tapered impedance-matching traveling-wave electrode architecture. A1 is the foundational application and will carry the broadest independent claims in the family. The specification will include a comprehensive description of the modulator architecture, including the optical waveguide structure, the segmented traveling-wave electrode with tapered impedance-matching characteristics, the electrical drive circuitry interface, and the multi-channel configuration for 800G/1.6T applications.
Independent claims: The broadest independent claims will recite the tapered impedance-matching traveling-wave electrode architecture at a level of generality sufficient to encompass the full range of taper profiles (linear, exponential, stepped, and hybrid) while clearly distinguishing over Pinnacle's uniform segmentation geometry. At minimum, the independent claims will recite: (i) a silicon-photonic substrate; (ii) at least one Mach-Zehnder interferometer formed in the substrate; (iii) a plurality of traveling-wave electrode segments disposed along the optical waveguide path; and (iv) a tapered impedance-matching characteristic in which the impedance of successive electrode segments varies progressively along the optical waveguide propagation direction.
Dependent claims: A robust set of dependent claims will layer in specific taper profiles, segment counts, impedance ratios, materials (e.g., copper, gold, aluminum), waveguide geometries, modulation bandwidth specifications, and multi-channel configurations.
Drafter: Christy Bauer (lead drafter), with technical input from Dr. Lena Strickland and Dr. Feng-Yi Chen. Peter Vassiliev will assist with prior art review, formal requirements, and filing logistics.
Prosecution strategy: We anticipate that USPTO examiners will cite Pinnacle's '417 and '662 patents as primary prior art references under 35 U.S.C. § 102 (anticipation) or § 103 (obviousness). Our planned response strategy is to distinguish the claimed tapered impedance-matching feature from Pinnacle's uniform segmentation, argue the absence of any teaching, suggestion, or motivation in the prior art to modify Pinnacle's uniform geometry to arrive at a tapered configuration, and, if necessary, present inventor declaration evidence under 37 C.F.R. § 1.132 to support the non-obviousness of the tapered approach. We will also emphasize the unexpected technical advantages of the tapered impedance-matching feature, including superior modulation bandwidth and reduced insertion loss, as supported by OWS's internal simulation and measurement data. Application A1 is the single most important filing in the family, and its loss or abandonment would eliminate OWS's ability to obtain the broadest claims covering the design-around.
Application A2 — U.S. Continuation
Filing type: U.S. continuation application under 35 U.S.C. § 120
Target filing date: Approximately March 2023 (Q1 2023)
Priority claim: Claims benefit of A1 (and through A1, the provisional 63/297,841)
Subject matter: Claims directed to alternative embodiments and dependent-claim subject matter from A1, elevated to independent claim status. A2 serves two primary purposes: first, it provides claim-set diversification by presenting claims with different scope and structure than those in A1, thereby creating multiple overlapping layers of patent protection; second, it serves as a hedge against potential narrowing amendments that may be required during prosecution of A1. If the A1 claims are narrowed during prosecution to overcome prior art rejections, the A2 claims — which will be independently pending — can be crafted to capture claim scope that was surrendered in A1.
Drafter: Christy Bauer, with input from Catherine Bloom on claim strategy.
Prosecution strategy: A2 will be filed while A1 is still pending, ensuring copendency. The claims will be drafted to avoid double-patenting issues with A1 (or, if necessary, a terminal disclaimer will be filed). A2 provides flexibility to pursue claim amendments in A1 without sacrificing overall portfolio breadth.
Application A3 — U.S. Continuation-in-Part (CIP)
Filing type: U.S. continuation-in-part under 35 U.S.C. § 120
Target filing date: Approximately June 2023 (Q2 2023)
Priority claim: Claims benefit of A1 (and through A1, the provisional 63/297,841) for subject matter supported by the provisional specification; new matter added in A3 will not enjoy the January 10, 2022 priority date
Subject matter: A3 will incorporate new matter from OWS's ongoing R&D activities, particularly enhanced tapered impedance-matching geometries that have been developed or are expected to be developed after the provisional filing date of January 10, 2022. OWS's engineering team, led by Dr. Strickland and Dr. Chen, is actively refining the tapered electrode design, and the A3 CIP is specifically reserved to capture these incremental innovations.
Named inventors: Same as A1 (Dr. Menon, Dr. Strickland, Dr. Chen, Dr. Dasgupta), with the possible addition of new contributors if additional inventors are identified in connection with the new matter.
Critical limitation: It is essential to understand that the CIP new matter will not enjoy the January 10, 2022 priority date. Only claim elements that are fully supported by the disclosure of the provisional specification (i.e., that satisfy the written-description and enablement requirements of 35 U.S.C. § 112(a) as of the provisional filing date) will be entitled to the provisional's priority date. Claim elements that rely on the new matter added in A3 will have an effective filing date of A3's actual filing date, likely in June 2023. This means that prior art dated between January 10, 2022 and the A3 filing date could be cited against claims that depend on the new matter.
Prosecution strategy: A3 provides a second layer of protection for OWS's design-around features, particularly for refined taper geometries that may prove to be more commercially significant than the original geometries disclosed in the provisional. The claims in A3 will be drafted to maximize the portion of each claim that is supported by the provisional specification, while adding specific limitations drawn from the new R&D data only where necessary to capture the most commercially relevant embodiments.
Application A4 — PCT International Application
Filing type: PCT international application under the Patent Cooperation Treaty
Target filing date: January 9, 2023
Receiving Office: United States Patent and Trademark Office (USPTO), acting as Receiving Office under the PCT
Priority claim: Claims priority to Provisional 63/297,841, filed January 10, 2022
Subject matter: A4 will include claims directed to the core modulator architecture and the tapered impedance-matching traveling-wave electrode, substantially mirroring the A1 claim set but with certain modifications to address international claim-format conventions. A4 will also include process claims directed to the electrode fabrication methodology, so as to provide a basis for European and Japanese prosecution of both apparatus and process claims.
PCT Chapter I Examination: International search and preliminary examination will be elected under PCT Chapter I. The International Searching Authority (ISA) will be the USPTO. We expect to receive the International Search Report and Written Opinion of the International Searching Authority (ISR/WO) approximately 16 to 18 months from the priority date, i.e., approximately July to August 2023.
Purpose within the family: A4 serves as the vehicle for entering the European regional phase (Application B3) and the Japanese national phase (Application B4). By filing A4 as a PCT application rather than filing directly at the EPO and JPO, OWS benefits from the 30-month national-phase entry deadline, which provides additional time to assess commercial priorities and refine claims before committing to the costs of regional- and national-phase prosecution.
30-month national-phase entry deadline: July 9, 2025 (calculated as 30 months from the January 10, 2022 priority date). This deadline applies to any jurisdictions beyond the EP and JP entries already planned for July 2023.
Drafter: Peter Vassiliev (lead), coordinating with Christy Bauer.
Chapter II (IPER): We do not recommend electing PCT Chapter II (International Preliminary Examination Report) at this time. The cost of Chapter II examination is not justified given that OWS plans to enter the European and Japanese national/regional phases well in advance of the 30-month deadline, and the Chapter I ISR/WO report will provide sufficient preliminary patentability guidance for our purposes.
Application A5 — PCT International Application
Filing type: PCT international application under the Patent Cooperation Treaty
Target filing date: January 9, 2023
Receiving Office: USPTO
Priority claim: Claims priority to Provisional 63/297,841, filed January 10, 2022
Subject matter: A5 is a second PCT filing, with claims directed to the packaging and thermal-management aspects of OWS's silicon-photonic modulator module. A5 is distinct from A4 in that A5 focuses on the module-level innovations (packaging, heat dissipation, thermal interface structures) rather than the core device-level modulator architecture.
Purpose within the family: A5 serves as the vehicle for entering the European regional phase (Application C2) and the Japanese national phase (Application C3), providing a basis for foreign patent protection on OWS's packaging and thermal-management innovations.
Chapter I ISR/WO report: Expected approximately August 2023.
30-month national-phase entry deadline: July 9, 2025.
Drafter: Peter Vassiliev, coordinating with Christy Bauer and Dr. Feng-Yi Chen.
C. Sub-Family B — Electrode Fabrication Process (4 Planned Applications)
Sub-Family B is directed to the fabrication process for the segmented traveling-wave electrode with tapered impedance-matching structure. Process claims are a critical complement to the apparatus and device claims in Sub-Family A, as they provide an independent basis for asserting patent rights against competitors who manufacture (or have manufactured on their behalf) electrode structures using OWS's proprietary fabrication methods, even if such competitors' final products are structurally distinguishable from OWS's apparatus claims.
Application B1 — U.S. Non-Provisional
Filing type: U.S. non-provisional utility application
Target filing date: Approximately July 2023 (Q3 2023)
Application number: To be assigned (anticipated serial number: 17/814,057)
Subject matter: Claims directed to the fabrication process for the segmented traveling-wave electrode with tapered impedance-matching structure. The claims will recite the key fabrication steps that are unique to creating the tapered electrode segments, including specific lithographic patterning steps, metal deposition sequences (e.g., copper damascene or gold electroplating processes), etch steps, and post-processing treatments. The specification will include detailed process-flow diagrams and fabrication parameters.
Prosecution strategy: We anticipate that the USPTO may issue a Restriction Requirement under 35 U.S.C. § 121, requiring election between the process claims and any apparatus claims that may be included in B1. Our plan is to include both process claims and apparatus claims directed to the electrode structure as fabricated in the initial filing, elect the process claims in response to the Restriction Requirement, and pursue the non-elected apparatus claims in a divisional application (B2). This strategy is designed to maximize the number of distinct claim sets that OWS can obtain from a single filing, while ensuring that the process claims — which are the primary objective of B1 — are prosecuted without delay.
Application B2 — U.S. Divisional
Filing type: U.S. divisional application under 35 U.S.C. § 121
Target filing date: To be filed upon receipt of a Restriction Requirement in B1 (placeholder; no fixed date)
Subject matter: B2 will pursue the non-elected claim set from B1. Based on the planned prosecution strategy, B2 is expected to carry apparatus claims directed to the electrode structure as fabricated — i.e., product-by-process claims or structural claims directed to the specific electrode geometry that results from the fabrication process claimed in B1.
Note: B2 is a placeholder in the current docket. It will not be filed until a Restriction Requirement is actually issued in B1. If the examiner does not issue a Restriction Requirement (a possibility, though we consider it unlikely given the distinct statutory categories of the process and apparatus claims), B2 may not be needed. We will reassess the B2 filing decision upon receipt of the first Office Action in B1.
Application B3 — European Regional Phase
Filing type: European regional-phase entry from PCT Application A4
Target entry date: Approximately July 2023
PCT parent: PCT/US2023/010584 (Application A4)
Filing authority: European Patent Office (EPO)
Foreign associate: Breitenfeld & Vogt Patentanwälte PartGmbB, Leopoldstrasse 44, 80802 Munich, Germany. Lead attorney: Dr. Matthias Vogt. B&V is a well-established patent law firm with deep expertise in semiconductor and photonics patent prosecution at the EPO.
Prosecution strategy: Upon entry into the European regional phase, we expect the EPO to issue a Rule 161/162 communication inviting the applicant to file observations, amendments, or a response to any deficiencies identified during the international phase. Subsequently, the EPO will conduct its own search and issue an Extended European Search Report (EESR), which will include the examiner's preliminary opinion on patentability. The response deadline for observations following the EESR is typically six months from the deemed date of notification.
European claims will need adaptation to comply with European Patent Convention (EPC) requirements, including, where appropriate, the two-part claim format (preamble and characterizing portion) that is customary in EPO practice. C&H will provide claim sets and prosecution instructions to B&V; B&V will handle translations into the required EPO languages, formal requirements, and direct communications with the EPO. Monthly status updates from B&V to C&H are planned, with quarterly summary reports to OWS.
Estimated costs per substantive EPO response: €3,500 to €5,000 (B&V professional fees), plus EPO official fees (approximately €580 for the examination fee; additional fees for designation, search, and grant).
Application B4 — Japanese National Phase
Filing type: Japanese national-phase entry from PCT Application A4
Target entry date: Approximately July 2023
PCT parent: PCT/US2023/010584 (Application A4)
Filing authority: Japan Patent Office (JPO)
Foreign associate: Nakashima & Togawa Patent Professional Corporation, 2-4-16 Toranomon, Minato-ku, Tokyo 105-0001, Japan. Lead attorney: Kenji Nakashima.
Translation: A full Japanese translation of the PCT application specification, claims, and abstract is required for national-phase entry. N&T will manage the translation process using its in-house translation team and will coordinate with C&H to ensure accuracy of technical terminology.
Examination request: Under Japanese patent law, an examination request must be filed within three years of the PCT international filing date. Since PCT Application A4 will be filed on January 9, 2023, the examination request deadline is January 9, 2026. Our recommended strategy is to defer the examination request until close to the three-year deadline, in order to maximize pendency and minimize near-term prosecution costs, unless commercial developments in the Japanese market dictate earlier action. If OWS identifies significant commercial activity or competitive threats in Japan that warrant accelerated prosecution, we can file the examination request earlier, and the JPO offers accelerated examination procedures (including the Patent Prosecution Highway program) that can be leveraged to expedite the process.
Status reporting: N&T will provide updates to C&H upon receipt of any JPO communication. C&H will consolidate and report to OWS.
D. Sub-Family C — Packaging & Thermal Management (3 Planned Applications)
Sub-Family C addresses OWS's innovations in advanced packaging and thermal management for the silicon-photonic modulator module. These innovations are distinct from the core modulator architecture and electrode fabrication process claims in Sub-Families A and B, and represent an additional layer of patent protection — an "IP moat" — around OWS's commercial products.
Application C1 — U.S. Non-Provisional
Filing type: U.S. non-provisional utility application
Target filing date: Late Q4 2023 or early Q1 2024
Application number: To be assigned (anticipated serial number: 18/102,776)
Subject matter: Claims directed to advanced packaging and thermal-management innovations for the silicon-photonic modulator module. Specific innovations include novel thermal interface structures, heat-spreader configurations, coefficient-of-thermal-expansion (CTE) matching substrates, and integrated thermal monitoring and feedback mechanisms designed to maintain optimal modulator performance across a wide range of operating temperatures.
Relationship to other applications: C1 is a standalone filing — it is not a continuation of A1. However, the C1 specification may reference and incorporate by reference portions of the A1 specification where relevant to the packaging context (e.g., descriptions of the modulator die that is packaged). C1 may claim priority to Provisional 63/297,841 directly for subject matter that is supported by the provisional specification, but the majority of the C1 claims are expected to be directed to innovations that postdate the provisional and that are the product of OWS's ongoing thermal-management R&D. To the extent C1 claims rely on subject matter not disclosed in the provisional, those claims will have an effective filing date of C1's actual filing date.
Dependency on R&D timeline: The filing timeline for C1 is dependent on the completion of OWS's ongoing thermal simulation and prototype validation work. Dr. Strickland and Dr. Chen have indicated that the thermal-management R&D is expected to yield publishable results by late 2023, at which point the data will be available for incorporation into the C1 specification. The filing timeline may shift if the R&D is delayed or if the results suggest a need for additional design iterations.
Drafter: Christy Bauer, with extensive technical input from Dr. Chen and Dr. Dasgupta.
Application C2 — European Regional Phase
Filing type: European regional-phase entry from PCT Application A5
Target entry date: Approximately July 2023
PCT parent: PCT/US2023/010612 (Application A5)
Foreign associate: Breitenfeld & Vogt Patentanwälte PartGmbB (Dr. Matthias Vogt)
Prosecution strategy: Similar to B3. Upon entry, expect Rule 161/162 communication from the EPO. An Extended European Search Report (EESR) is anticipated in mid-2024 or later, depending on EPO workload and examination timing. B&V will handle all EPO communications in coordination with C&H. Claim adaptation to EPC requirements will be managed by B&V with C&H input.
Application C3 — Japanese National Phase
Filing type: Japanese national-phase entry from PCT Application A5
Target entry date: Approximately July 2023
PCT parent: PCT/US2023/010612 (Application A5)
Foreign associate: Nakashima & Togawa Patent Professional Corporation (Kenji Nakashima)
Translation and filing: N&T will manage Japanese translation and filing formalities.
Examination request deadline: Three years from the PCT international filing date of A5, i.e., January 9, 2026. As with B4, we recommend deferring the examination request to near the deadline unless commercial developments warrant earlier action.
IV. Claim Differentiation Strategy vis-à-vis Pinnacle Optics Prior Art
A. Overview of Pinnacle's Patent Claims
A thorough understanding of Pinnacle Optics' patent claims is essential to crafting OWS's claims in a manner that maximizes scope while maintaining clear differentiation from the prior art. The following summarizes the key independent claims of Pinnacle's two relevant patents. Full claim texts are reproduced in Appendix C.
U.S. Patent No. 10,823,417 (the "'417 Patent"): The '417 patent contains three independent claims (Claims 1, 12, and 20). Independent Claim 1 is representative and recites, in relevant part:
A silicon-photonic Mach-Zehnder modulator comprising: a silicon substrate having an optical waveguide formed therein defining a first arm and a second arm of a Mach-Zehnder interferometer; a plurality of traveling-wave electrode segments disposed along the optical waveguide, each electrode segment having a substantially uniform impedance-matching characteristic across the plurality of segments; a radio-frequency (RF) input configured to receive a modulation signal; and an optical output configured to output a modulated optical signal.
The critical element in Claim 1 of the '417 patent for purposes of differentiation is the recitation of "a substantially uniform impedance-matching characteristic across the plurality of segments." This language requires that the electrode segments share a common impedance-matching design — i.e., that they are uniform, not tapered or progressively varying. Independent Claims 12 and 20 contain similar limitations expressed in system-level and method-of-modulation claim formats, respectively.
The dependent claims of the '417 patent add further specificity regarding segment count (e.g., "between 4 and 16 segments"), electrode material (e.g., "copper or gold"), and waveguide geometry (e.g., "rib waveguide" or "ridge waveguide"). None of the dependent claims recite or suggest a tapered or progressively varying impedance-matching characteristic.
U.S. Patent No. 11,105,662 (the "'662 Patent"): The '662 patent, a continuation of the '417 patent, contains narrower but related claims. Independent Claim 1 of the '662 patent recites, in relevant part:
A silicon-photonic modulator comprising: a Mach-Zehnder interferometer formed in a silicon-on-insulator substrate; a segmented traveling-wave electrode having N electrode segments, where N is between 6 and 12, the electrode segments being spaced apart by a uniform segment pitch of between 200 micrometers and 800 micrometers; each electrode segment having an impedance substantially equal to a characteristic impedance of the electrode transmission line.
The '662 patent's claims are more specific than those of the '417 patent, reciting numerical ranges for segment count, segment spacing, and impedance characteristics. However, the '662 claims retain the fundamental requirement that each segment have "an impedance substantially equal to a characteristic impedance" — i.e., a uniform impedance across segments. The '662 patent does not disclose or suggest any variation, tapering, or progressive change in impedance along the electrode path.
In summary, both Pinnacle patents describe and claim a uniform (non-tapered) electrode segmentation geometry. This is the key point of distinction upon which OWS's entire claim differentiation strategy is founded.
B. OWS's Tapered Impedance-Matching Feature as Design-Around
OWS's core innovation — and the centerpiece of the planned application family — is the traveling-wave electrode architecture in which the electrode segments are tapered along the optical waveguide path with progressively varying impedance-matching characteristics. Rather than maintaining a uniform impedance across all electrode segments (as in Pinnacle's design), OWS's modulator employs a deliberate and controlled variation in the impedance of successive electrode segments, such that the impedance changes progressively from the RF input end to the terminated end of the traveling-wave electrode.
This tapered impedance-matching architecture yields significant technical advantages over Pinnacle's uniform-impedance approach, including:
• Superior modulation bandwidth: The progressive impedance taper reduces parasitic reflections and improves the velocity match between the electrical RF signal and the optical wave propagating in the waveguide, resulting in a wider electro-optic modulation bandwidth.
• Reduced insertion loss: The tapered electrode geometry reduces RF losses along the electrode path, leading to lower insertion loss in the modulated optical signal.
• Improved Signal integrity: The progressive impedance matching suppresses standing-wave effects and improves the uniformity of the modulation index across multiple channels in a multi-channel modulator configuration, which is particularly important for 800G and 1.6T applications.
Based on our review of the prior art, including the Pinnacle patents, the broader patent literature, and the published technical literature in the field of silicon-photonic modulators, the tapered impedance-matching feature as implemented in OWS's architecture is not disclosed or claimed in any Pinnacle patent or other known prior art reference. This assessment is preliminary and will be refined in connection with the freedom-to-operate analysis being prepared for delivery in Q3 2022.
All Sub-Family A independent claims will recite the tapered impedance-matching limitation as a distinguishing structural element. This limitation serves the dual purpose of (i) differentiating OWS's claims from Pinnacle's prior art and (ii) capturing the specific design-around feature that OWS is incorporating into its next-generation commercial products.
Application A1 carries the broadest claims to this feature and is therefore the single most critical application in the family. If A1 were lost or abandoned, OWS would lose its ability to obtain the broadest possible claims covering the tapered impedance-matching design-around. Application A3 (the CIP) provides a second layer of protection by capturing enhanced tapered geometries developed through ongoing R&D, but A3's new matter will not enjoy the January 10, 2022 priority date, making it more vulnerable to intervening prior art.
C. Claim Drafting Guidelines
The following guidelines will govern claim drafting across all sub-families:
Independent Claims: Each independent claim must recite the tapered impedance-matching structure with sufficient specificity to distinguish over Pinnacle's uniform-impedance prior art, while maintaining sufficient breadth to capture competitor variations and design-arounds of OWS's own technology. The key recitation in each independent apparatus claim should include language such as: "a plurality of traveling-wave electrode segments disposed along the optical waveguide, wherein at least a subset of the electrode segments has a progressively varying impedance-matching characteristic along the direction of optical wave propagation." This language captures the essence of the tapered feature without unnecessarily limiting the claim to any specific taper profile. Apparatus, system, and method claims should all include the tapered impedance-matching element as a distinguishing limitation.
Dependent Claims: Dependent claims will layer in progressively more specific limitations, including:
• Specific taper profiles: linear taper, exponential taper, stepped taper, and hybrid taper profiles;
• Segment counts: specific ranges (e.g., "between 4 and 24 segments") and preferred values;
• Impedance ratios: the ratio of the impedance of the first electrode segment to the impedance of the last electrode segment (e.g., "between 1.05:1 and 2.5:1");
• Materials: copper, gold, aluminum, and alloy compositions;
• Multi-channel configurations: specific numbers of Mach-Zehnder modulators on a single chip (e.g., 4-channel, 8-channel);
• Modulation bandwidth specifications: minimum 3-dB electro-optic bandwidth values;
• Integration features: co-integrated driver circuitry, photodetector monitors, and wavelength-division multiplexing (WDM) elements.
Process Claims (Sub-Family B): Process claims will recite the fabrication steps that are unique to creating the tapered electrode segments, including lithographic patterning steps that define the progressively varying electrode segment geometries, metal deposition sequences (e.g., damascene processes, electroplating with varying current densities), etch steps, chemical-mechanical polishing (CMP), and post-deposition annealing. The process claims should be drafted to capture both OWS's preferred fabrication flow and reasonably foreseeable alternative fabrication methods.
Packaging and Thermal Claims (Sub-Family C): Packaging claims will recite thermal-management structures that are specific to the tapered-electrode modulator module, including thermal interface materials, heat-spreader geometries optimized for the non-uniform power dissipation profile of the tapered electrode, CTE-matched substrates, and integrated thermal-monitoring circuitry. These claims serve as an additional moat around OWS's commercial products, capturing the system-level innovation that complements the device-level claims in Sub-Families A and B.
D. Anticipated Prosecution Arguments and Examiner Responses