Contract analysis

I. INTRODUCTORY LETTER / TRANSMITTAL September 1, 2023 To: European Patent Office Receiving Section 80298 Munich Germany From: Breitenfeld & Vogt Patentanwälte PartGmbB Leopoldstrasse 44 80802 Munich, Germany 1.1 Reference Information Dear Sir or Madam, 1.2 Identification of Filing This response is filed on behalf of the applicant, Optiwave Semiconductor Corp., a corporation organized and existing under the laws of t

1. Amendments to the claims as permitted under Rule 161(2) EPC. The applicant submits a set of amended claims, narrowing the scope of the independent claims to more precisely define the packaging architecture and thermal management features of the claimed silicon-photonic Mach-Zehnder modulator assemblies, thereby further distinguishing the claimed invention over the prior art cited in the International Search Report

2. Amendments to the description to conform the description to the requirements of the European Patent Convention. These amendments include the incorporation of references to the prior art cited in the International Search Report and Written Opinion in the introductory portion of the description, as required by Rule 42(1)(b) EPC, as well as conforming amendments to align the description with the amended claim scope.

3. Voluntary submission of amended claims addressing matters raised in the International Search Report and Written Opinion (Chapter I report issued August 2, 2023) for PCT/US2023/010612 (designated as Application A5 in the applicant's prosecution docket). The applicant addresses the examiner's findings regarding novelty and inventive step, and presents supporting remarks in Section VI below.

4. No observations under Rule 161(1) EPC are submitted at this time. The applicant elects to amend the application in the manner described herein, and respectfully reserves the right to submit further observations and arguments upon receipt of the Extended European Search Report. The amended claims are submitted in clean copy format as Appendix A and in marked-up format (showing additions by underlining and deletions

II. PROCEDURAL BACKGROUND 2.1 International Application History The present European patent application EP 23 765 901.7 derives from International Application No. PCT/US2023/010612, designated in the applicant's prosecution docket as Application A5. The international application was filed on January 9, 2023, at the United States Receiving Office (USPTO/RO) under the Patent Cooperation Treaty. The international applic

III. SUMMARY OF THE INTERNATIONAL SEARCH REPORT AND WRITTEN OPINION FINDINGS 3.1 Cited Prior Art References The International Search Report issued on August 2, 2023, by the USPTO as International Searching Authority (ISA/US) for PCT/US2023/010612 cited the following prior art references: Pinnacle Optics, Inc. is a Delaware corporation headquartered at 7200 Gateway Boulevard, Newark, California 94560, and is recognize

IV. AMENDED CLAIMS 4.1 Basis for Amendments The claim amendments set forth herein are made under Rule 161(2) EPC, which permits the applicant to amend the application of its own volition upon entry into the European regional phase in response to the Rule 161/162 communication. The amendments are also consistent with the amendment opportunities available under Article 19 PCT and Rule 137(2) EPC. All amendments find fu

V. AMENDMENTS TO THE DESCRIPTION 5.1 Adaptation of Description to EPC Requirements The applicant has made the following conforming amendments to the description to satisfy the formal requirements of the European Patent Convention: Terminology Adaptations: References to United States-specific patent terminology have been converted to EPC-compliant language where appropriate. For example, references to "claims" as "the

VI. REMARKS IN SUPPORT OF AMENDMENTS 6.1 Response to Novelty Objections The applicant respectfully submits that the amended claims are novel over each of the cited prior art references, considered individually, and addresses the specific novelty objections raised in the Written Opinion as follows. Distinguishing Amended Claim 1 Over D2 (U.S. Patent No. 11,105,662, Pinnacle Optics): The Written Opinion found original

VII. FORMAL MATTERS 7.1 Power of Attorney / Authorization Breitenfeld & Vogt Patentanwälte PartGmbB is authorized to act as European professional representative for Optiwave Semiconductor Corp. before the European Patent Office pursuant to a general authorization filed with the EPO on July 8, 2023, upon entry of the present application into the European regional phase. A copy of the general authorization (Form EPO 10

1. Dr. Rajan Menon, residing at 2817 Greenmont Lane, Los Altos, California 94024, United States of America

2. Dr. Lena Strickland, residing at 14 Thornberry Circle, Sunnyvale, California 94086, United States of America

3. Dr. Feng-Yi Chen, residing at 951 Rosewood Drive, Palo Alto, California 94303, United States of America

4. Dr. Arjun Dasgupta, residing at 408 Bayshore Road, Apt. 12B, Mountain View, California 94043, United States of America Each of the named inventors has executed a declaration of inventorship and waiver of right to be mentioned as inventor (to the extent applicable) in connection with the filing of the international application. The applicant is the sole assignee of the entire right, title, and interest in and to th

1. A multi-channel silicon-photonic Mach-Zehnder modulator assembly, comprising: a silicon photonic integrated circuit die comprising a plurality of Mach-Zehnder modulator channels, each modulator channel comprising at least one optical waveguide region; a thermally conductive submount comprising a coefficient-of-thermal-expansion-matched aluminum nitride substrate having a thermal conductivity of at least 170 W/m·K,

2. The assembly of claim 1, wherein the aluminum nitride substrate has a coefficient of thermal expansion in the range of 4.0 to 5.5 ppm/°C, and the copper-tungsten alloy body of the lid structure has a coefficient of thermal expansion in the range of 6.0 to 7.5 ppm/°C.

3. The assembly of claim 1 or claim 2, wherein the patterned indium-tin alloy solder preform has a thickness in the range of 15 to 50 micrometers, and wherein each through-aperture has a lateral dimension that is at least 1.2 times a lateral dimension of the corresponding optical waveguide region.

4. The assembly of any one of claims 1 to 3, wherein the thermal resistance of the first thermal zone is in the range of 0.6 to 1.0°C/W, and the thermal resistance of the second thermal zone is in the range of 0.3 to 0.6°C/W.

5. The assembly of any one of claims 1 to 4, wherein the internal thermal vias of the lid structure comprise copper pillars embedded in the copper-tungsten alloy body, the copper pillars having a diameter in the range of 100 to 500 micrometers and arranged in an array aligned with the plurality of Mach-Zehnder modulator channels.

6. The assembly of any one of claims 1 to 5, wherein the first thermal zone and the second thermal zone are thermally isolated from each other by a thermal resistance of at least 15°C·cm²/W.

7. The assembly of any one of claims 1 to 6, further comprising an external heat sink attached to the heat sink mounting surface of the lid structure, the external heat sink providing a total thermal dissipation capacity of at least 15 watts at an ambient temperature of 85°C. Claims 8–13: Method Claims

8. A method of assembling a thermally managed silicon-photonic Mach-Zehnder modulator package, the method comprising: providing a thermally conductive submount comprising a coefficient-of-thermal-expansion-matched aluminum nitride substrate having a thermal conductivity of at least 170 W/m·K; forming a patterned indium-tin alloy solder preform having a plurality of through-apertures, each through-aperture configured

9. The method of claim 8, further comprising establishing a multi-zone thermal interface arrangement by configuring the patterned solder preform to provide a first thermal zone associated with the plurality of Mach-Zehnder modulator channels and a second thermal zone associated with a driver electronics region, the first and second thermal zones having independently specified thermal resistance values.

10. The method of claim 8 or claim 9, wherein the temperature-profiled reflow process comprises: a preheat stage at a temperature in the range of 100 to 150°C for a duration of 30 to 90 seconds; a ramp stage increasing the temperature from the preheat temperature to the peak temperature at a rate not exceeding 3°C per second; and a peak stage at the peak temperature not exceeding 200°C for a duration of 10 to 30 seco

11. The method of any one of claims 8 to 10, wherein forming the patterned solder preform comprises: providing a sheet of indium-tin alloy having a thickness in the range of 15 to 50 micrometers; and forming the plurality of through-apertures by laser ablation or mechanical punching, each through-aperture having a lateral dimension that is at least 1.2 times a lateral dimension of the corresponding optical waveguide

12. The method of any one of claims 8 to 11, wherein establishing the multi-zone thermal interface arrangement further comprises thermally isolating the first thermal zone from the second thermal zone by a thermal resistance of at least 15°C·cm²/W.

13. The method of any one of claims 8 to 12, further comprising attaching an external heat sink to the heat sink mounting surface of the lid structure, the external heat sink providing a total thermal dissipation capacity of at least 15 watts at an ambient temperature of 85°C. APPENDIX B — AMENDED CLAIMS (MARKED-UP COPY) CLAIMS (Marked-Up Copy — Additions Underlined, Deletions Struck Through) Claims 1–7: Apparatus Cl

1. A multi-channel silicon-photonic Mach-Zehnder modulator assembly, comprising: a silicon photonic integrated circuit die comprising a plurality of Mach-Zehnder modulator channels, each modulator channel comprising at least one optical waveguide region; a thermally conductive submount ~~comprising a thermally conductive substrate~~ comprising a coefficient-of-thermal-expansion-matched aluminum nitride substrate havi

2. The assembly of claim 1, wherein the aluminum nitride substrate has a coefficient of thermal expansion in the range of 4.0 to 5.5 ppm/°C, and ~~wherein the submount has a thermal conductivity of at least 170 W/m·K~~ the copper-tungsten alloy body of the lid structure has a coefficient of thermal expansion in the range of 6.0 to 7.5 ppm/°C.

3. The assembly of claim 1 or claim 2, wherein the ~~thermal interface material comprises an indium-based solder preform~~ patterned indium-tin alloy solder preform has a thickness in the range of 15 to 50 micrometers, and wherein each through-aperture has a lateral dimension that is at least 1.2 times a lateral dimension of the corresponding optical waveguide region.

4. The assembly of any one of claims 1 to 3, wherein ~~the indium-based solder preform has a specified thermal conductivity~~ the thermal resistance of the first thermal zone is in the range of 0.6 to 1.0°C/W, and the thermal resistance of the second thermal zone is in the range of 0.3 to 0.6°C/W. ~~5. The assembly of claim 4, wherein the indium-based solder preform has a thickness in the range of 15 to 50 micrometer

5. The assembly of any one of claims 1 to 4, wherein the internal thermal vias of the lid structure comprise copper pillars embedded in the copper-tungsten alloy body, the copper pillars having a diameter in the range of 100 to 500 micrometers and arranged in an array aligned with the plurality of Mach-Zehnder modulator channels.

6. The assembly of any one of claims 1 to 5, wherein ~~the modulator channels are substantially thermally isolated from a driver electronics region~~ the first thermal zone and the second thermal zone are thermally isolated from each other by a thermal resistance of at least 15°C·cm²/W. ~~7. The assembly of claim 6, wherein a driver electronics region is substantially thermally isolated from the modulator channels.~~

7. The assembly of any one of claims 1 to 6, ~~wherein the lid structure comprises a metal lid with external cooling fins~~ further comprising an external heat sink attached to the heat sink mounting surface of the lid structure, the external heat sink providing a total thermal dissipation capacity of at least 15 watts at an ambient temperature of 85°C. ~~8. The assembly of claim 7, wherein the metal lid is a copper

8. A method of assembling a thermally managed silicon-photonic Mach-Zehnder modulator package, the method comprising: providing a thermally conductive submount ~~comprising a thermally conductive substrate~~ comprising a coefficient-of-thermal-expansion-matched aluminum nitride substrate having a thermal conductivity of at least 170 W/m·K; forming a patterned indium-tin alloy solder preform having a plurality of thro

9. The method of claim 8, further comprising establishing a multi-zone thermal interface arrangement by configuring the patterned solder preform to provide a first thermal zone associated with the plurality of Mach-Zehnder modulator channels and a second thermal zone associated with a driver electronics region, the first and second thermal zones having independently specifie