Enhancing the Performance of Electro-Optical Heterodyne Receivers Using Gain Switched Photonic Local Oscillators

The performance of a Gain Switched (GS) optical source used as a Photonic Local Oscillator (PLO) in an Electro-Optical (EO) heterodyne receiver is experimentally evaluated and compared to the use of a traditional linearly modulated PLO. The EO heterodyne receiver used is based on an Ultra Nonlinear Semiconductor Optical Amplifier (XN-SOA) that provides a compact, cost effective and energy efficient receiver with a remote distribution of both PLO and Intermediate Frequency (IF) signals and a direct 50-ohms input for the Radiofrequency (RF) component. The comparison between both GS and linearly modulated PLO is made in terms of the conversion efficiency (conversion ratio); linearity (1-dB compression point) and noise (integrated RMS timing jitter). The analysis results in a significant improvement of the evaluated figures of merit when using a Gain Switched PLO.