Cascaded wavelength conversion based on cross-gain modulation and cross-phase modulation in SOAs

Abstract

All-optical wavelength converters (AOWCs) that utilize nonlinearities in semiconductor optical amplifiers (SOAs) have attracted considerable research interest. AOWCs based on cross gain modulation (XGM) have a large dynamic range of the input optical signal power but a low extinction ratio (ER) and a high chirp, whereas AOWCs based on cross phase modulation (XPM) provide a low chirp and a high ER but suffer from a relative small input power dynamic range. We point out that there seems to be some complementarity between XGM and XPM. Based on this, we propose a novel scheme for cascaded wavelength conversion based on cross gain modulation and cross phase modulation in SOAs thus is expected to have a high ER and a large input power dynamic range simultaneously. The wavelength conversion operation includes two stages, that is, XGM in the first stage followed by the stage of XPM. In the XGM stage, we use a band pass filter to increase the frequency response of the SOA. In the XPM, we use the bidirectional input scheme for MZI to improve the response of XPM and cancel XGM-induced intensity unbalance to get a relative perfect interference.