PTAB

IPR2020-01347

Cisco Systems Inc v. Oyster Optics LLC

Log In
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 an optical transmitter for telecommunications that can operate in two distinct modes. The transmitter includes a laser, a phase modulator, and a controller that, in a first mode, phase-modulates light from the laser, and in a second, alternate mode, amplitude-modulates the light, with a switch to select between the modes based on an input data stream.

3. Grounds for Unpatentability

Ground 1: Obviousness over Barr and Hofstetter - Claims 1-2, 4-9, and 17-19 are obvious over Barr in view of Hofstetter.

  • Prior Art Relied Upon: Barr (Patent 4,763,357) and Hofstetter (Patent 5,903,376).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Barr teaches a secure communications transmitter that switches between different modulation techniques (e.g., amplitude modulation (AM) and phase modulation (PM)) at random intervals to prevent interception. While applicable to fiber optics, Barr does not detail the optical components. Hofstetter discloses the necessary components for a modern optical transmitter, including a laser, an optical modulator, and a control unit capable of generating both phase-modulated (e.g., PSK) and amplitude-modulated (e.g., ASK, QAM) optical signals via either direct or external modulation. Petitioner contended that combining Hofstetter’s optical transmitter components with Barr’s modulation-switching system results in the claimed dual-mode transmitter. The combined system’s controller would switch between a phase-modulation mode and an amplitude-modulation mode at different times to achieve Barr's security objectives.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the references to implement Barr's security-enhancing technique of switching modulation types in a high-speed, high-bandwidth optical context. This combination would leverage the known security advantages of Barr and the performance benefits of the optical components taught by Hofstetter.
    • Expectation of Success: Petitioner asserted a high expectation of success because Barr explicitly states its applicability to fiber optic channels and is compatible with various modulation techniques, including the AM and PM schemes detailed in Hofstetter.

Ground 2: Obviousness over Sasaki and Ishii - Claims 1-2, 4, and 17-19 are obvious over Sasaki in view of Ishii.

  • Prior Art Relied Upon: Sasaki (Patent 6,486,992) and Ishii (a 1995 IEEE article).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sasaki describes an optical transmitter that dynamically switches its modulation format (e.g., between phase-modulated QPSK and amplitude-modulated higher-order QAM) to optimize communication quality based on factors like distance. Sasaki’s modulator generates a modulated radio frequency (RF) signal to drive a light-emitting element. Ishii discloses an RF-to-Optic Converter (ROC) that implements external modulation, converting a modulated RF signal into an optical signal with the same modulation format. Petitioner asserted that a POSITA would replace Sasaki’s light-emitting unit with a laser and Ishii’s ROC. In this combination, Sasaki’s controller would select the modulation format (QPSK or QAM), and the resulting RF signal would drive Ishii's ROC to modulate light from the laser, creating the claimed dual-mode transmitter.
    • Motivation to Combine: A POSITA would integrate Ishii’s ROC into Sasaki’s system to gain the benefits of external modulation, such as improved signal quality from reduced spectral spreading (“chirping”), while retaining Sasaki’s intelligent modulation-switching capability.
    • Expectation of Success: Success was expected because Ishii’s ROC is explicitly designed to convert the types of modulated RF signals (QPSK and QAM) that Sasaki’s system produces into optical signals.

Ground 3: Obviousness over Sasaki, Ishii, and Davarian - Claim 5 is obvious over the combination of Sasaki, Ishii, and Davarian.

  • Prior Art Relied Upon: Sasaki (Patent 6,486,992), Ishii (a 1995 IEEE article), and Davarian (a 1989 IEEE article).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on Ground 2 to address the "operator-activated" switch limitation of claim 5. Davarian discloses a multipurpose digital modulator where the modulation format can be selected via a "manual and/or an electronic switch." Petitioner argued it would have been obvious to add Davarian’s operator-activated manual switch to the Sasaki/Ishii combination. This would provide a manual override or alternative to Sasaki’s automated switching logic.
    • Motivation to Combine: A POSITA would add a manual switch to provide an operator with the flexibility to select modulation systems for purposes like field testing, troubleshooting, or overriding the automatic system, a common design goal for configurable communications equipment.
    • Expectation of Success: Adding a manual switch to a system with automated controls was argued to be a simple and well-known design choice for providing enhanced flexibility and control.

4. Key Claim Construction Positions

  • "amplitude-modulating [] light from the laser" (claims 1, 17): Petitioner proposed this term means "causing the intensity of the laser light to be altered to create an amplitude-modulated optical signal." This construction was argued as crucial because it encompasses both direct modulation (altering the laser’s power source) and external modulation (altering the light after emission), allowing prior art teaching either method to be applied.
  • "a switch for switching between the first and second modes" (claim 4): Petitioner proposed this term encompasses "hardware or software that functions to cause the controller to switch between the first and second modes." This broad construction was asserted to cover control circuitry and software-based logic, not just a physical toggle, which is relevant for applying prior art like Barr and Sasaki where the switching is performed by integrated circuits controlled by a microprocessor.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-2, 4-9, and 17-19 of the ’500 patent as unpatentable.