Optically Controlled RF Phase Shifts in SOAs by Adding the XGM Response of an Optical Signal

This study focuses on the possibility to achieve optical control of the radiofrequency (RF) phase shifting in semiconductor optical amplifiers (SOA). Based on the addition of the cross-gain modulation response (XGM) of a CW signal at an SOA output, the phase shift can be independently controlled from the operating conditions of the SOA (optical input power and bias current) by varying the external CW power. The impact of the XGM response of the amplified spontaneous emission (ASE) on the signal relative phase shift has also been studied. Small-signal analysis is developed and a numerical calculation is used to analyze the controllable RF phase shift. The measurement results for several control signal powers are given.