Small-Signal Analysis in Two Calculation Sections and Experimental Validation of Up-Converted Coherent Population Oscillations in Semiconductor Optical Amplifiers

Abstract

This paper presents theoretical and experimental analysis of up-converted coherent population oscillations (Up-CPO) in semiconductor optical amplifiers (SOAs) for tunable optical phase shift applications at high frequencies. The study of Up-CPO frequency response is carried out by a small-signal analysis of a SOA modeled by two calculation sections in order to better take into account the nonlinear effects such as the SOA gain saturation. We demonstrate that we can fully determine the dynamic parameters of Up-CPO from the experimental frequency response of an optical probe signal obtained by cross-gain modulation mechanism. The Up-CPO frequency responses are measured for three SOAs with different cut-off frequencies up to 18.45 GHz. We finally validate experimentally the obtained analytical frequency responses for the three SOAs over different operating points, each characterized by the corresponding optical gain.