Study of injection-locking and injection-pulling in injection-locked optoelectronic oscillator under radio frequency signal injection

Abstract

We present a detailed study of injection-locking (IL) and injection-pulling behavior of an IL single-loop optoelectronic oscillator (OEO) when injected by radio frequency (RF) signal. From the locking equation, the expression for the output spectrum of the IL-OEO under RF injection is derived in the time domain, to evaluate the spurious performance of the system. The frequency response of the spurious outputs due to RF injection signal is investigated in terms of the injection transfer function. Also, a dual-loop model of the IL-OEO is developed to study the phase noise performance of the system with a cofrequency RF injection signal. Also, the effect of Gaussian minimum shift keying signal interference on the IL-OEO output spectrum is investigated. An analytical expression for the side-mode attenuation is presented to describe the influence of IL on the side-modes of free-running OEO. The experimental results corroborating the theoretical findings are given.