Agilent Technologies, Inc.

Mohan Gurunathan

Richard D Pering

William Ian McAlexander

Zoltan Azary

Bogdan Szafraniec

Tun Sein Tan

Joseph Newhall West

Greg C Richtenburg

In one embodiment, a method determines the spectral content of an optical signal. Specifically, the optical signal and an optical local oscillator (LO) signal are provided to inputs of an optical hybrid (e.g., an N&#xd7;N optical coupler where N is greater than two). The phase-diverse components from the optical hybrid are photodetected allowing for mixing of the optical signal and the optical local oscillator. Bandpass filtering is performed to eliminate or reduce relative intensity noise (RIN). The filtered signals are mixed with an electrical LO signal. A quadrature representation of a phase-diverse heterodyne signal is generated from signals from the mixing. The negative image and the positive image from the quadrature representation are separated. The spectral content of the optical signal is determined from the images.

Systems and methods for determining the spectral content of an optical signal

An optical fiber device with reduced thermal sensitivity comprises a first optical fiber arm having a first composite coefficient of thermal expansion and a first length and a second optical fiber arm having a second composite coefficient of thermal expansion and a second length. A ratio of the first and second lengths inversely matches a ratio of the first and second composite coefficients of thermal expansion to minimize thermal sensitivity in the device.

Systems and methods for fiber optic devices with reduced thermal sensitivity

A phase-diverse coherent optical spectrum analyzer is presented. An optical receiver receives a first input signal and a second input signal, and produces at least a first output signal, a second output signal, and a third output signal based on mixing the first input signal and the second input signal. A processing unit isolates heterodyne components from the first output signal, the second output signal and the third output signal, wherein the heterodyne components comprise a first signal and a second signal that represent the phase-diverse nature of the optical mixing process. Phase diversity of the heterodyning between the first input signal and the second input signal is achieved by the coherent optical spectrum analyzer.

Phase-diverse coherent optical spectrum analyzer

A high dynamic range receiver includes a detector that produces a current at a pair of terminals. A first gain element, implemented as a current-to-voltage converter for example, is coupled to the first terminal, receiving the current and generating a first output signal corresponding to the current. A second gain element, implemented as a current-to-voltage converter for example, is coupled to the second terminal, receiving the current and generating a second output signal corresponding to the received current. A switch selectively couples the first output signal or the second output signal to a port based on a comparison of at least one of the first output signal and the second output signal to a threshold.

High dynamic range receiver

A zero calibration system and method for an optical receiver include an illuminated photodetector, switchably coupled to an amplifier. The photodetector is de-coupled from the amplifier while illumination of the photodetector is maintained and an error signal is measured at the output of the amplifier The photodetector is then coupled to the amplifier and subsequent signals measured at the output of the amplifier are corrected according to the measured error signal, based on a comparison of the relative values of a feedback resistor, coupled between the output and an input of the amplifier, and an equivalent resistance of the photodetector. When the ratio of the feedback resistor to the equivalent resistance does not exceed a predetermined threshold, the subsequently measured signals at the output of the amplifier are corrected by offsetting the subsequently measured signals by the measured error signal. When the ratio exceeds the predetermined threshold, the subsequently measured signals at the output of the amplifier are corrected by offsetting the subsequently measured signals by the measured error signal as modified by a correction factor.

Growing community of inventors

San Francisco, CA, United States of America

Mohan Gurunathan