Eoptolink Technology USA Inc. v. Applied Optoelectronics, Inc.

Eoptolink Technology USA Inc. initiated an Inter Partes Review (IPR2026-00019) at the Patent Trial and Appeal Board (PTAB) to challenge U.S. Patent No. 9,448,367, owned by Applied Optoelectronics, Inc.. Eoptolink Technology USA Inc. is the U.S. entity of Eoptolink Technology Inc., Ltd., a prominent Chinese manufacturer of high-speed optical transceivers and modules used in telecommunications, data centers, and AI applications. Applied Optoelectronics, Inc. (AOI) is a U.S.-based operating company that designs, manufactures, and sells fiber-optic networking products for internet data centers, cable television (CATV), telecom, and fiber-to-the-home (FTTH) markets.

This IPR proceeding is directly related to a patent infringement lawsuit filed by Applied Optoelectronics against Eoptolink in the U.S. District Court for the Northern District of California (Case No. 3:24-cv-08165), filed on November 19, 2024. In that district court action, AOI alleges that several Eoptolink optical transceivers, including various 400G QSFP-DD and 100G QSFP28 models, infringe AOI's optical transceiver patents. U.S. Patent No. 9,448,367, titled "Optical coupling device," describes an optical coupling device that facilitates the reflection of light beams between two optical fiber arrays using an optical lens array with a reflective layer, a core technology in optical transceivers.

The procedural posture of this case is at the Patent Trial and Appeal Board (PTAB), where the IPR petition (IPR2026-00019) was filed on October 10, 2025. The PTAB ultimately decided not to institute the review, with its status listed as "Not Instituted - Procedural." Specifically, the Board entered a "Denial on the Request for Discretionary Denial" on February 3, 2026, followed by a "Decision of Termination," leading the petitioners to request a refund of post-institution fees. This non-institution means the validity challenge for U.S. Patent No. 9,448,367 did not proceed to a full trial before the PTAB. The district court case (Applied Optoelectronics, Inc. v. Eoptolink Technology USA Inc.) has been stayed pending these IPR institution decisions.

This case is notable due to its context within the highly competitive fiber-optic networking industry, where both parties are significant operating companies. The IPR's direct linkage to an ongoing district court patent infringement lawsuit underscores the strategic importance of PTAB proceedings in challenging asserted patents and influencing the course of parallel litigation. The "Not Instituted - Procedural" status, particularly following a denial of a discretionary denial request and subsequent termination, reflects the complex and evolving landscape of PTAB institution decisions, including the Director's discretion in managing the PTAB's docket.

Legal Developments and Outcome in Eoptolink v. Applied Optoelectronics Patent Litigation

This case involves a patent infringement lawsuit filed by Applied Optoelectronics, Inc. (AOI) against Eoptolink Technology USA Inc. in district court, which led Eoptolink to file multiple Inter Partes Review (IPR) petitions at the Patent Trial and Appeal Board (PTAB), including IPR2026-00019. The district court litigation is currently stayed pending the outcomes of these IPRs.

District Court Litigation: Applied Optoelectronics, Inc. v. Eoptolink Technology USA Inc. (N.D. Cal. Case No. 5:24-cv-08165-NW)

Filing & Initial Pleadings:
Applied Optoelectronics, Inc. (AOI) initiated a patent infringement lawsuit against Eoptolink Technology USA Inc. on November 19, 2024, in the U.S. District Court for the Northern District of California. AOI's complaint alleged infringement of multiple optical transceiver patents, including U.S. Patent No. 9,448,367, and sought monetary damages and a permanent injunction. Eoptolink, in its defense, contended that each of the six asserted patents in the lawsuit was invalid.

Discovery Milestones:
Between June and December 2025, the parties engaged in initial discovery. AOI served its infringement contentions on June 13, 2025, and Eoptolink served its invalidity contentions on August 18, 2025.

Pre-trial Motions:
On December 5, 2025, both parties filed a Joint Administrative Motion to Stay the district court proceedings. This motion was based on Eoptolink's recently filed IPR petitions challenging the patents-in-suit. The District Court, presided over by Judge Noël Wise, granted the motion to stay on January 13, 2026. The court vacated all existing deadlines and stayed the case until June 5, 2026, instructing the parties to file joint status reports within seven days of any PTAB decisions regarding the institution of the IPRs.

Claim Construction (Markman):
Before the stay, the district court had set a schedule for claim construction. The parties were due to exchange preliminary claim constructions and extrinsic evidence by December 19, 2025, and submit a Joint Claim Construction and Prehearing Statement and Expert Reports by January 13, 2026, with claim construction briefing anticipated to begin in February 2026. However, these deadlines were subsequently vacated by the January 13, 2026, stay order.

Current Posture:
The district court case is currently stayed, with a further case management conference scheduled for June 30, 2026.

Parallel PTAB IPR Proceedings

Eoptolink, as the defendant in the district court infringement case, filed several IPR petitions challenging the validity of AOI's asserted patents. Applied Optoelectronics, Inc. (AOI) subsequently filed Requests to the Director for Discretionary Denial against some of these petitions.

IPR2026-00019 (U.S. Patent No. 9,448,367):
Eoptolink Technology USA Inc. filed an IPR petition challenging U.S. Patent No. 9,448,367 on October 10, 2025. The PTAB ultimately decided not to institute this IPR, with the status recorded as "Not Instituted - Procedural." AOI had filed a Request to the Director for Discretionary Denial of this petition, along with others, citing grounds similar to those raised in IPR2026-00122. These discretionary denials often relate to factors like the Fintiv framework, which considers the proximity of a district court trial date and the overlap of issues.

Other IPRs Filed by Eoptolink:
Eoptolink filed additional IPR petitions challenging other patents asserted by AOI:

• IPR2026-00094: Challenging U.S. Patent No. 10,578,818, filed on November 5, 2025. AOI also filed a Request to the Director for Discretionary Denial for this petition.
• IPR2026-00122: Challenging U.S. Patent No. 10,714,890, filed on November 25, 2025.
• IPR2026-00123: Challenging U.S. Patent No. 11,177,887, filed on December 1, 2025.

The decision of the PTAB Director to deny institution for IPR2026-00019 (and potentially others) means that the validity challenge for U.S. Patent No. 9,448,367 will not proceed before the PTAB, thereby leaving the patent's validity to be fully litigated in the district court if the stay is lifted. The PTAB institution rate has seen significant changes, with Director John Squires taking over all IPR institution decisions in October 2025, around the time these IPRs were filed.

Eoptolink Technology USA Inc. is represented by the following counsel from Perkins Coie LLP:

• Arpita Bhattacharyya, Ph.D.

  • Role: Counsel for Petitioners (likely lead or co-lead counsel in the IPR).
  • Firm: Perkins Coie LLP, Palo Alto, California.
  • Note: Dr. Bhattacharyya focuses on patent and trade secret litigation, post-grant proceedings at the USPTO (including IPRs and PGRs), and IP counseling. She has experience in a range of technologies, including emerging and deep technologies like AR/VR, AI, robotics, liquid cooling, medical devices, diagnostics, computer software, and hardware. She has managed complex patent litigation cases before district courts, the ITC, and the U.S. Court of Appeals for the Federal Circuit.

• Robert F. McCauley

  • Role: Counsel for Petitioners (likely lead or co-lead counsel in the IPR).
  • Firm: Perkins Coie LLP, Palo Alto, California.
  • Note: Mr. McCauley is an experienced trial lawyer specializing in intellectual property litigation, including patent litigation, trade secrets, and trial practice. He has first-chaired more than 30 jury trials and over 50 bench trials, litigating across various technologies such as semiconductor devices, optical amplifiers and networks, liquid cooling systems for data centers, medical devices, software and hardware, and pharmaceuticals. He has litigated before numerous U.S. district courts, the ITC, the U.S. Court of Appeals for the Federal Circuit, and the PTAB.

Both attorneys were noted as partners who joined Perkins Coie's Intellectual Property and Patent Litigation practices in Palo Alto in March 2025. They are also listed as featured speakers discussing "Evolving Strategies in U.S. Patent Litigation" with a focus on federal district courts and the PTAB, indicating their expertise in this area.

Applied Optoelectronics, Inc., as the Patent Owner in IPR2026-00019, is represented by attorneys from Weintraub Tobin Chediak Coleman Grodin Law Corporation. The primary counsel identified are:

• Name and role: Jo Dale Carothers, Ph.D., Shareholder, Chair of the Intellectual Property group, Registered Patent Attorney.

  • Firm and office location: Weintraub Tobin Chediak Coleman Grodin Law Corporation, San Francisco, CA.
  • Note on relevant patent litigation experience: Dr. Carothers is an experienced intellectual property litigator and registered patent attorney who advises clients on a wide range of IP issues, including patents, and proceedings before the United States Patent and Trademark Office (USPTO). She has represented Applied Optoelectronics Inc. in IPR petitions. She has significant experience in electronics, embedded systems, and wireless communications.

• Name and role: Eric A. Caligiuri, Of Counsel, Registered Patent Attorney.

  • Firm and office location: Weintraub Tobin Chediak Coleman Grodin Law Corporation, Los Angeles, CA.
  • Note on relevant patent litigation experience: Mr. Caligiuri advises clients on complex intellectual property disputes and transactions, with a practice focusing on patent litigation in federal district courts, state courts, and before the International Trade Commission (ITC). He is also admitted to practice before the U.S. Patent and Trademark Office and handles patent and trademark prosecution.

These attorneys also represent Applied Optoelectronics, Inc. in the related district court patent infringement case, Applied Optoelectronics, Inc. v. Eoptolink Technology USA Inc., Case No. 5:24-cv-08165-NW (N.D. Cal.).