PTAB

IPR2017-02190

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 ’952 patent describes a fiber optic data transmission system using differential phase shift keying (DPSK) to enhance security against eavesdropping. The system employs a transmitter with a time-delayed control circuit and a phase modulator, and a receiver with a corresponding interferometer to encode and decode phase-modulated optical signals.

3. Grounds for Unpatentability

Ground 1: Claims 1-3 and 5 are obvious over Bauch in view of Schneider

  • Prior Art Relied Upon: Bauch (Patent 6,826,371) and Schneider (Patent 6,700,907).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Bauch discloses the foundational optical DPSK communication system, including a transmitter with a delayed-feedback exclusive-OR (XOR) encoder and a receiver with a corresponding delay-line interferometer. However, Bauch lacks specific details for a stable phase modulator. Petitioner contended that Schneider remedies this deficiency by teaching a Mach-Zehnder (MZ) modulator with a detailed feedback control circuit that includes a digital-to-analog converter (DAC). This DAC, part of a bias control loop, alters the modulator's phase to compensate for environmental factors, thereby satisfying the final limitation of independent claim 1. Petitioner further mapped Bauch’s XOR encoder to claim 2, Bauch’s inherent 180-degree phase difference in its receiver to claim 3, and Schneider’s bias control algorithm to the "phase-compensation circuit" of claim 5.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) designing the DPSK system in Bauch would combine it with Schneider’s well-known MZ modulator and control circuitry. The motivation was to address the known need for long-term operational stability by compensating for environmental noise, temperature changes, and component aging, a detailed solution which Schneider provides and Bauch lacks. This combination represented the use of a known solution to solve a known problem for predictable results.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved implementing a standard DPSK system (Bauch) with a well-understood, stable modulator technology (Schneider) to achieve the desired stability benefits.

Ground 2: Claim 4 is obvious over Bauch and Schneider in view of Heflinger

  • Prior Art Relied Upon: Bauch (Patent 6,826,371), Schneider (Patent 6,700,907), and Heflinger (Patent 6,396,605).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds upon the system established by the Bauch and Schneider combination to address claim 4, which depends from claim 3 and adds the limitation of an "additional phase modulator" in one of the receiver interferometer's arms for tuning purposes. Petitioner argued that while the Bauch/Schneider combination discloses the system of claim 3, it does not teach this additional element. Heflinger discloses an optical interferometer for a DPSK receiver that includes an integrated thermal heater in one arm to precisely tune the optical path difference. Petitioner asserted that this thermal heater functions as the claimed "additional phase modulator" by altering the phase of light to compensate for temperature variations.
    • Motivation to Combine: A POSITA would combine Heflinger’s teachings for two primary reasons. First, Bauch explicitly references Heflinger as describing a method for "precisely controlling the optical path difference of such an interferometer," directly guiding a skilled artisan to Heflinger's solution. Second, it was a widely known problem that optical interferometers are thermally unstable. Heflinger provided a known and practical solution—a tunable arm—to achieve the predictable result of improved temperature stability in the Bauch receiver.
    • Expectation of Success: A POSITA would expect success in substituting Bauch's generic interferometer with Heflinger's improved, tunable version to solve the known problem of thermal instability, particularly given Bauch's express suggestion to consider Heflinger's teachings.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-5 of Patent 6,476,952 as unpatentable under 35 U.S.C. §103.