Computation of Phase Noise Spectrum in Optoelectronic Oscillator

Abstract

A method for the phase noise characterization of single-loop optoelectronic oscillators (OEO) is presented. Based on the injection-pulling dynamics of OEO under radio frequency (RF) signal injection, this method is used to compute the phase noise spectrum of a free-running single-loop OEO. From the injection locking equation, the expression for the output RF spectrum of single-loop OEO under the influence of a single sinusoidal RF signal injection is derived and this analysis is then utilized to study the RF output power spectrum of the single-loop OEO when injected by two weak and equally strong RF sinusoidal signals with mirror frequencies with respect to the free-running frequency of the OEO. An expression for the far-out phase noise spectrum of a free-running single-loop OEO is presented to capture the far-out phase noise characteristics of the OEO. Also, we derive the expression for the close-in phase noise spectrum of the free-running single-loop OEO by considering the multiplicative noise as the overall loop-gain perturbation in the OEO loop. The experimental results are also given in partial support to the conclusions of the analysis.