1/F Frequency Noise Effects on Self-Heterodyne Linewidth Measurements for Coherent Communications

Abstract

Prepared for Jie tfportzfent of die Air Force andt-,r GmCenime F L')h2fl-90,C.0092, ABSTRACTThe effects of l/f frequenc) noise on self-heterodyne detection are described and the results are applied to the problem of laser-diode-linew idth measurement. Laser diode line%%idths determined by sef-heterod)ne methods are not adequate predictors of coherent communications system performance because these measurements often include significant broadening due to I/f frequenc) noise. In this report, the autocorrelation functIor. and power spectrum of the detected belf-heterodyne photoLurrent are de eloped in terms of an arbitrary frequency noise spectrum and then e aluated for both the white and the 1/f components of the frequenc) noise. From numerical analysis, the power spectrum resulting from the l/f frequency noise is sho%%n to be approximately Gaussian and an empirical expression is gi-en for its lineNidth. These results are applied to the problem of self-heterodyne linexxidth measurements for c-oherent optical communication. and the amount of broadening due to l/f frequency noise is predicted. Two methods are then prox ided for estimating the portion of the measured self-heterod) ne line idth due to the white component of the frequency noise and the portion due to 1/f frequency noise.