SINGLE-FREQUENCY LASER PHASE-NOISE LIMITATION IN SINGLE-MODE OPTICAL-FIBER COHERENT-DETECTION SYSTEMS WITH CORRELATED FIELDS.

Abstract

THE PHASE NOISE AFFECTING THE BEAT PHOTOCURRENT PRODUCED BYCOHERENT DETECTION OF A SINGLE-FREQUENCY LASER FIELD WITH ATIME-DELAYED AND FREQUENCY-SHIFTED IMAGE OF ITSELF IN A HETERODYNE TWO-WAVE INTERFEROMETRIC SYSTEM USING A SINGLE-MODE OPTICAL FIBER IS STUDIED AS A FUNCTION OF SOURCE SPECTRUM AND PHASE-DECORRELATION TIME UNDER THE ASSUMPTIONS OF QUANTUM LASER PHASE NOISE AND HIGH-LOCAL-OSCILLATION LEVEL. THE INFLUENCE ON THE PHOTOCURRENT SPECTRUM OF PARTIAL CORRELATION BETWEEN DETECTED FIELDS IS POINTED OUT. THESE CALCULATIONS AREAN EXTENSION OF A PREVIOUSLY REPORTED HIGH-RESOLUTION SPECTROSCOPIC METHOD AND ACCOUNT FOR THE PHASE-NOISE LIMITATION IN UNBALANCED HETERODYNE FIBER SENSORS AND HETERODYNE-TRANSMISSION RECEIVERS WITH AN OPTICAL REFERENCE WAVE GENERATED FROM THE RECEIVED SIGNAL. AN EXPERIMENTAL STUDY IS REPORTED ANDRESULTS ARE FOUND TO BE IN GOOD AGREEMENT WITH THEORY.