Wave division multiplexing channel telemetry by phase modulation

Abstract

A wave division multiplexing system in which low frequency intensity modulation of the optical channels is avoided in order to reduce or substantially prevent inter-channel cross-talk of low frequency telemetry signals by phase modulating the low frequency telemetry signal so as to recover the transmitted signal at the receiver. The system includes multiple transmitters and receivers. Each transmitter includes an optical source, such as a laser, a radio frequency generator having a low frequency telemetry signal impressed thereon, and an optical phase modulator. The phase modulated low frequency telemetry signal generated by each transmitter is combined using a multiplexer before being amplified and transmitted through a single optical fiber. A demultiplexer receives the transmitted signal and separates it into respective optical channels based on the particular frequency of each transmitter. Respective signals for each optical channel are transmitted to an associated receiver. Each receiver includes a splitter for tapping off a portion of power into a first portion and a second portion. A data recovery device reestablishes data information from the first portion of power, while an interferometer and detector are used to recover the low frequency telemetry information from the second portion of power.