PTAB

IPR2020-00326

Infinera Corp v. Oyster Optics LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Dual-Mode Fiber Optic Telecommunications System and Method
  • Brief Description: The ’500 patent describes a dual-mode optical telecommunications system. It discloses a transmitter using a single laser that can be controlled to operate in two distinct modes: a first mode for transmitting amplitude-modulated optical signals and a second mode for transmitting phase-modulated optical signals, with a receiver that includes an interferometer to process the received signals.

3. Grounds for Unpatentability

Ground 1: Obviousness over Barr, Hofstetter, and Henry - Claim 16 is obvious over Barr in view of Hofstetter and Henry.

  • Prior Art Relied Upon: Barr (Patent 4,763,357), Hofstetter (Patent 5,903,376), and Henry (Patent 4,754,452).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of the three references teaches every element of challenged claim 16. Barr teaches a secure communication system that switches between different modulation techniques (including amplitude modulation and phase modulation) at random intervals to prevent interception. While not exclusively optical, Barr explicitly states its applicability to fiber optic links. Hofstetter provides the specific optical components and methods to realize Barr’s concept, disclosing an optical transmitter with a laser and an external modulator. Hofstetter's controller can generate amplitude-modulated signals (by directly modulating the laser's current) and phase-modulated signals (by applying a modulated voltage to the external modulator while the laser emits a constant-intensity light). Henry addresses the receiver side, teaching a system for detecting phase-modulated optical signals. Critically, Henry discloses using an interferometer to convert the received phase-modulated signal into an intensity-modulated signal, which can then be converted to an electrical signal by a photodetector.
    • Petitioner asserted that combining these teachings results in the claimed invention. A POSITA would start with Barr’s secure, dual-mode modulation scheme. To implement it optically, the POSITA would incorporate the laser, external modulator, and control unit from Hofstetter to create a "Modified Optical Transmitter" capable of switching between amplitude and phase modulation. This combined transmitter would be connected to an optical fiber, as taught by both Barr and Hofstetter. Finally, to receive and demodulate the phase-modulated signals, the POSITA would implement a receiver containing an interferometer, as taught by Henry.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would be motivated to combine Barr and Hofstetter to achieve the security benefits of Barr’s switchable modulation scheme within a high-bandwidth, high-speed optical system, for which Hofstetter provides the essential building blocks. The motivation to then incorporate Henry’s teachings stems from the need to solve the consequential problem created by the Barr/Hofstetter combination: detecting the transmitted phase-modulated signals. Henry taught that using an interferometer was a known, primary approach for this purpose, representing one of a finite number of predictable solutions a POSITA would naturally consider.
    • Expectation of Success: Petitioner argued a POSITA would have had a reasonable expectation of success in making this combination. Barr’s disclosure of its applicability to optical communications and its generic controller design would suggest compatibility with Hofstetter’s standard optical components. The systems in Barr and Hofstetter are both based on transmitting digital data, ensuring compatibility. Furthermore, incorporating Henry’s interferometer into the receiver would be a straightforward integration, as it is a known solution for a known problem, and both Hofstetter and Henry describe similar receiver fundamentals (e.g., use of a photodiode connected to an optical fiber).

4. Key Claim Construction Positions

  • Term: "a laser for transmitting amplitude-modulated signals ... and phase-modulated signals" (from claim 16).
  • Proposed Construction: Petitioner argued this term should be construed to mean "a laser for use in connection with transmitting" such signals. This construction was presented as critical because it encompasses systems where the laser's output is externally modulated (as taught in Hofstetter for phase modulation) in addition to systems where the laser is directly modulated (as taught in Hofstetter for amplitude modulation). This interpretation allows Hofstetter’s single laser, which can either be directly modulated or provide a constant-wave input to an external modulator, to satisfy the claim limitation.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claim 16 of the ’500 patent as unpatentable under 35 U.S.C. §103.