PTAB

IPR2020-00325

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 an optical transmitter for telecommunications that can operate in two different modes. The system includes a laser, a phase modulator, and a controller that can switch between a first mode (transmitting phase-modulated optical signals) and a second mode (transmitting amplitude-modulated optical signals).

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 4, 6-9, and 17-19 are obvious over Barr in view of Hofstetter.

  • Prior Art Relied Upon: Barr (Patent 4,763,357), Hofstetter (Patent 5,903,376).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Barr teaches a data transmitter that improves security by switching between different modulation techniques, including phase modulation (PM) and amplitude modulation (AM), at random intervals. Hofstetter discloses a complete optical transmitter with a laser, an optical modulator, and a control unit capable of generating both phase-modulated (e.g., PSK) and amplitude-modulated (e.g., ASK) optical signals. The combination results in Barr’s controller directing Hofstetter’s optical components to switch between phase and amplitude modulation modes based on an input data stream, thereby meeting the limitations of the independent claims.
    • Motivation to Combine: A POSITA would combine these references to implement Barr's security-enhancing modulation switching technique in a high-bandwidth optical communications context. Barr itself suggests its invention has applications in fiber optic links, providing a direct motivation to use an optical transmitter like that taught by Hofstetter. This combination would achieve the security benefits of Barr with the speed and bandwidth advantages of optical transmission.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because Barr’s system is described as compatible with various carrier media, including fiber optics, and various modulation techniques, including the AM and PM techniques disclosed by Hofstetter. Both systems are designed to operate on digital data streams.

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

  • Prior Art Relied Upon: Sasaki (Patent 6,486,992), Ishii (a 1995 IEEE journal publication).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Sasaki describes an optical transmission apparatus that dynamically switches its modulation format (e.g., between QPSK phase modulation and higher-order QAM amplitude modulation) based on communication distance and speed. Ishii teaches an efficient RF-to-Optic converter (ROC) that uses a laser to convert modulated RF signals into corresponding modulated optical signals. Petitioner argued for modifying Sasaki’s light emitting unit by incorporating Ishii’s laser and ROC. In this combination, Sasaki’s controller selects a modulation format and generates a corresponding RF signal (QPSK or QAM), which is then fed into Ishii’s ROC to produce the final switched optical signal.
    • Motivation to Combine: A POSITA would be motivated to integrate Ishii's ROC into Sasaki's system to gain the benefits of external modulation, such as reduced signal chirp and improved signal quality, while retaining Sasaki’s intelligent, adaptive modulation switching capability. Further motivation existed to incorporate a laser for its known advantages in wireless optical communications, including higher modulation frequency and power.
    • Expectation of Success: Success was expected because both Sasaki and Ishii operate using compatible RF signals and modulation formats (QPSK and QAM). Ishii’s ROC is explicitly designed to convert such RF signals into optical signals, making it a suitable component to integrate into Sasaki’s transmitter architecture.

Additional Grounds

Petitioner asserted an additional obviousness challenge against claim 5, arguing it would be obvious to modify the Sasaki/Ishii combination with the teachings of Davarian (a 1989 IEEE magazine article). Davarian teaches a digital modulator with a manual, operator-activated switch for selecting the modulation format, which Petitioner argued would be a simple and desirable addition to provide manual override or testing capabilities.

4. Key Claim Construction Positions

  • "amplitude-modulating [] light from the laser" (claims 1, 17): Petitioner proposed this phrase encompasses “causing the intensity of the laser light to be altered to create an amplitude-modulated optical signal.” This construction was argued to cover both direct modulation (altering the laser’s power source) and external modulation (altering the light after it has been emitted), both of which are disclosed in the prior art and consistent with the patent’s specification.
  • "as a function of the electronic data stream" (claim 1): Petitioner proposed this means the modulation is “based at least in part on the electronic data stream.” This construction was asserted to be consistent with the intrinsic record, where the input data stream dictates the resulting modulated output signal.
  • "in direct relation to the input data stream" (claim 2): Petitioner proposed this means amplitude modulating light as a function of the input data stream “without using an output of a delayed-feedback exclusive-or gate.” This construction distinguishes the claimed direct modulation path from an alternate, more complex path described in the ’500 patent’s specification.

5. Relief Requested

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