PTAB

IPR2017-01725

Cisco Systems Inc v. Oyster Optics LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Fiber Optic Data Transmission System
  • Brief Description: The ’816 patent discloses a fiber optic data transmission system intended to provide enhanced security against eavesdropping. The system employs a form of differential phase-shift keying (DPSK), where a transmitter uses a controller with a delayed-feedback exclusive-OR (XOR) gate to phase-modulate a continuous wave laser signal, and a receiver uses an interferometer with a corresponding delay to decode the data.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4, and 6 are obvious over Kaneda in view of Heflinger.

  • Prior Art Relied Upon: Kaneda (Japanese Application Publication No. S61-127236) and Heflinger (Patent 6,396,605).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kaneda disclosed all elements of a complete DPSK communication system as claimed in the ’816 patent, including a transmitter with a "finite sum logic conversion circuit" (an XOR gate with feedback delay) controlling a phase modulator, and a receiver with an interferometer. However, Kaneda’s interferometer is constructed using free-space optics (mirrors and prisms). Heflinger, which relates to DPSK demodulators, expressly disclosed that the optical paths of an interferometer could be implemented using various known materials, including optical fiber.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) designing the DPSK system in Kaneda would combine it with Heflinger’s teachings by substituting optical fibers for the free-space paths in the interferometer. The motivation was to achieve predictable and well-known benefits, as optical fiber provides better environmental stability and a higher tolerance to vibration and shock compared to free-space optics. This was presented as a simple substitution of one known element for another to obtain predictable results.
    • Expectation of Success: A POSITA would have had a high expectation of success, as using optical fiber for interferometer arms was a standard and preferred implementation at the time.

Ground 2: Claims 1-4 and 6 are obvious over Kaneda, Heflinger, and Alexander.

  • Prior Art Relied Upon: Kaneda, Heflinger, and Alexander (Patent 5,726,784).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds upon the combination of Kaneda and Heflinger by adding Alexander to address the laser wavelength limitations of dependent claims 2 and 3. Alexander disclosed a continuous wave laser for wavelength division multiplexing (WDM) systems with a precise operating wavelength that varies by only 0.1 nm (one angstrom). This level of precision satisfies the limitations of claims 2 (< 2 nm variation) and 3 (< 1 nm variation).
    • Motivation to Combine: Petitioner contended that Kaneda itself acknowledged the problem of "waveform distortion occurring due to effects of wavelength dispersion" from a laser. A POSITA implementing Kaneda's system would therefore be motivated to use a more precise and stable laser source, such as the one taught by Alexander, to improve system performance and mitigate known distortion issues. The laser from Alexander was argued to be a mere substitution of one known component for another.
    • Expectation of Success: Using a precise laser as taught by Alexander in the Kaneda system would have predictably resulted in improved signal quality and reduced distortion.

Ground 3: Claims 5, 19, and 20 are obvious over Kaneda, Heflinger, and Corke.

  • Prior Art Relied Upon: Kaneda, Heflinger, and Corke (Patent 5,510,917).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground adds Corke to the Kaneda/Heflinger combination to teach the monitoring features of claims 5, 19, and 20. Corke disclosed a system for monitoring communications in an optical network where a tap coupler diverts a portion of an incoming signal to a detector. This detector monitored the intensity (i.e., energy level or amplitude) of the signal to detect faults. This directly mapped to the "tap detection monitor" and "energy level detector" limitations.
    • Motivation to Combine: A POSITA would be motivated to add the monitoring features of Corke to the communication system of Kaneda for the common purpose of improving network reliability and enabling fault detection. Applying this known technique to Kaneda's system was argued to be an obvious improvement.
    • Expectation of Success: A POSITA would expect that adding a standard tap coupler and detector to the receiver of the Kaneda system would successfully provide performance monitoring capabilities without negatively impacting the system's primary data transmission function.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including claims challenged over Kaneda alone (Ground 2); Kaneda and Alexander (Ground 4); Kaneda and Corke (Ground 6); and four-way combinations including all references (Grounds 7 and 8). These grounds relied on the same core prior art teachings and combination rationales outlined above.

4. Relief Requested

  • Petitioner requested institution of an inter partes review (IPR) and cancellation of claims 1-20 of Patent 6,469,816 as unpatentable.