US 8805185

As a senior US patent analyst, here is a concise summary of US patent 8,805,185.

Patent Information:

• Title: Wavelength-division multiplexing transmission device
• Assignee: Mitsubishi Electric Corp
• Inventor: Hajime Okada
• Filing Date: June 20, 2011
• Issue Date: August 12, 2014
• Abstract: A wavelength-division multiplexing transmission device including: a dummy light source configured to emit and quench dummy light; a monitoring unit configured to monitor an optical level relating to the received wavelength-division multiplexed light; a dummy light controller configured to control the dummy light source to emit dummy light in case where the monitoring unit determines based on the monitored optical level that the wavelength-division multiplexed light is in a condition of input interruption; and a multiplexer configured to multiplex the light of the wavelength modulated based on the transmission data and the dummy light emitted by the dummy light source, wherein the transmitter transmits wavelength-division multiplexed light generated by the multiplexer.

Plain-Language Overview of Independent Claim:

This patent introduces a system for maintaining stable optical signal strength in a wavelength-division multiplexing (WDM) network, particularly in scenarios where a signal may be temporarily interrupted. The core of the invention is a device that can detect a loss of the incoming light signal and, in response, inject a "dummy" light signal to take its place.

• Independent Claim 1: The primary claim describes a WDM transmission device that includes both a receiver and a transmitter. This device is designed to handle situations where some light signals are meant to be received and processed, while others are simply passed through to the next node in the network. The key components are:
  • A dummy light source that can be turned on and off.
  • A monitoring unit that continuously checks the power level of the incoming light signals.
  • A dummy light controller that, upon detecting a signal interruption by the monitoring unit, activates the dummy light source.
  • A multiplexer that combines the locally generated data signals with the dummy light signal (when it's active) to create a new, stable output signal for transmission.

In essence, this claim outlines a fail-safe mechanism. If the incoming "pass-through" signal is lost, the device intelligently substitutes it with a locally generated, content-free light signal. This prevents the downstream optical amplifiers from becoming unstable due to the sudden drop in total optical power, thus maintaining the overall integrity and quality of the network.

Litigation Search:

A search of the CAFC (Court of Appeals for the Federal Circuit) dockets for 2026 for "US patent 8805185" yielded no results. As of today, May 5, 2026, there is no indication of any appellate litigation involving this patent in the specified period. There is no certainty that this patent has not been or will not be the subject of litigation in other courts or in other time periods.