Georgia Tech Research Corporation

Princeton Lightwave, Inc.

Ketan Mukund Patel

Stephen E Ralph

Mark Itzler

Steven W McLaughlin

Xudong Jiang

Cenk Argon

A negative feedback avalanche diode for detecting the receipt of a single photon is described. The photodetector comprises a load element having two load states, one characterized by high impedance and the other characterized by low impedance. The load state of the load element is controlled by a control signal generated within the negative feedback avalanche diode itself.

Two-state negative feedback avalanche diode having a control element for determining load state

The present invention enables the detection of light using an APD that has high gain and/or a wide range of operating temperature. A first APD is biased with a voltage bias that is controlled based on the breakdown voltage of a second APD, which is thermally coupled with the first APD. Changes in the breakdown voltage of the second APD due to aging, temperature chances, and the like, are reflective of changes in the breakdown voltage of the first APD. As a result, the first APD can be operated with greater stability and reliability at high gain and over larger temperature excursions than APDs known in the prior art.

Optical receiver comprising breakdown-voltage compensation

Systems for detection and compensation of modal dispersion in an optical fiber system including a multisegment photodetector coupled to an end of an optical fiber for detecting optical signals exiting the optical fiber and for converting the optical signals to an electrical output are provided. A representative multisegment photodetector includes a plurality of photodetector regions configured such that each of the plurality of photodetectors detects a portion of the plurality of optical signals exiting the end of the optical fiber and modifies the signal to reduce the affects of modal dispersion. Other systems are also provided.

Segmented photodetectors for detection and compensation of modal dispersion in optical waveguides

A system is described that includes a system for correcting modal dispersion and errors in an optical fiber system. The system includes a multisegment photodetector coupled to an end of an optical fiber for detecting optical signals exiting the optical fiber and for converting the optical signals to an electrical output, the multisegment photodetector including a plurality of photodetector regions configured such that one of the plurality of photodetectors regions intercepts a mode in a manner distinct from another of the plurality of photodetectors. The system also includes logic configured to receive a resultant signal output from the photodetector regions and provide forward error correction decoding of the resultant signal.

Spatially resolved equalization and forward error correction for multimode fiber links

Methods for detecting and compensating for multiple optical signals produced in a multi-mode fiber system are provided. A representative method includes detecting a plurality of optical signals radiating from an end of the multi-mode fiber by a multisegment photodetector having different detector regions that detect different portions of the plurality of optical signals, and modifying detected signal by the multisegment photodetector to reduce the affects of modal dispersion among the plurality of optical signals. Other methods also are provided.

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Yardley, PA, United States of America

Ketan Mukund Patel