Cambridge Industries USA Inc v. Applied Optoelectronics Inc

1. Case Identification

• Case #: IPR2025-00437
• Patent #: 10,788,690
• Filed: January 17, 2025
• Petitioner(s): Cambridge Industries USA, Inc.
• Patent Owner(s): Applied Optoelectronics, Inc.
• Challenged Claims: 1-19

2. Patent Overview

• Title: Optical Isolator Array
• Brief Description: The ’690 patent is directed to an optical isolator array for use in an optical subassembly module, such as a transmitter optical subassembly (TOSA) within a transceiver. The invention purports to solve alignment and space constraint issues by mounting a plurality of optical isolators on a common magnetic base in a predefined, parallel arrangement, secured with an adhesive, thereby creating a compact and modular profile.

3. Grounds for Unpatentability

Ground 1: Claims 1-10 are unpatentable under 35 U.S.C. § 102 as anticipated by Wang

• Prior Art Relied Upon: Wang (Chinese Patent No. CN 208421455U).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Wang, which teaches a multichannel optical isolator array, discloses every limitation of independent claim 1 and dependent claims 2-10. Wang’s disclosed substrate served as the claimed "first magnetic base" with a "mounting surface." On this base, Wang mounted multiple optical isolators in parallel channels, secured by an adhesive that fills gaps to ensure positional accuracy, thus meeting the limitations for the plurality of isolators and the adhesive layer. Petitioner further asserted that Wang discloses the dependent claim features, including forming the base from a permanent magnet (claim 2), generating a magnetic field that intersects the isolators to establish a propagation direction (claim 3), including a Faraday rotator in each isolator (claim 4), using angled light-receiving surfaces to reduce back reflection (claim 5), arranging isolators uniformly (claim 6), applying adhesive between isolators (claim 7), and including a flat substrate mating surface (claim 8). Finally, Petitioner pointed to embodiments in Wang that disclose a second magnetic base coupled to the top of the isolators to generate a second, annular magnetic field, anticipating claims 9 and 10.

Ground 2: Claims 11-19 are obvious over Wang in view of Xiong

• Prior Art Relied Upon: Wang (Chinese Patent No. CN 208421455U), Xiong (Patent 9,563,073).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that this combination renders the transceiver claims obvious. Xiong was argued to supply the foundational elements of claim 11: an optical transceiver with a housing, a TOSA, and a ROSA. Xiong’s TOSA includes a substrate and a plurality of laser diodes emitting different wavelengths. Petitioner contended it would have been obvious to replace the single isolator concept in Xiong’s TOSA with the superior multi-channel optical isolator array taught by Wang. In this combination, Wang’s magnetic base would serve as the TOSA substrate, and its array of isolators would be mounted adjacent to Xiong’s laser diodes for optical alignment. The limitations of dependent claims 12-19 were argued to be obvious for the same reasons claims 2-10 were anticipated by Wang’s express teachings.
  • Motivation to Combine: A POSITA would combine the references to achieve the recognized goals of optimizing space and simplifying assembly in optical transceivers. Wang explicitly provides a compact, modular isolator array designed for multi-channel components. Xiong provides the exact context—a TOSA within a transceiver—where such an improved component would be utilized. Petitioner argued that since both references use the Faraday effect for light propagation control, a POSITA would naturally look to incorporate Wang's improved array into a system like Xiong's to gain Wang's stated benefits of reduced size and simplified assembly.
  • Expectation of Success: A POSITA would have had a high expectation of success, as the combination involves placing a known type of component (a modular isolator array) into its intended environment (a TOSA) to achieve predictable improvements in form factor and manufacturability. The integration was argued to be straightforward and would not produce any new or unpredictable results.

4. Arguments Regarding Discretionary Denial

• Petitioner presented arguments that discretionary denial would be inappropriate under both 35 U.S.C. §325(d) and 35 U.S.C. §314(a).
• §325(d) (Same or Substantially Same Art): Petitioner argued that the grounds rely on prior art (Wang and Xiong) that is substantively different from the art considered during prosecution. The Examiner considered references disclosing only single optical isolators, whereas the petition's primary reference, Wang, teaches an optical isolator array. This distinction was argued to be material to patentability, and therefore the art is not the same or cumulative of that previously presented to the Office.
• §314(a) (Fintiv Factors): Petitioner contended that the Fintiv factors weigh strongly against discretionary denial. The parallel district court litigation is in a very early stage, with the trial scheduled for June 8, 2026, well after the statutory deadline for a Final Written Decision. Investment by the court and parties was described as minimal, with a claim construction hearing not yet held. To address issue overlap, Petitioner stipulated it would not pursue the same invalidity grounds in the district court if the IPR is instituted. Finally, the merits of the petition were argued to be strong, presenting challenges not previously considered by the USPTO.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-19 of the ’690 patent as unpatentable.