Wavelength converter based on four-wave mixing in a bulk semiconductor optical amplifier assisted by a Sagnac Interferometer and polarizer

Several works has recently been focused on the study of the Four Wave Mixing (FWM) process developed into a Semiconductor Optical Amplifier (SOA) for the implementation of all-optical wavelength converters. In this process, the maximum conversion efficiency is generally obtained at very close pump and probe wavelengths. In this condition, however, the engendered signal has a significant intensity. For this reason, it is important to develop filtering techniques allowing isolating the conjugated signal from all the others. In this manner, we show in this work a novel configuration of a wavelength converter based on FWM developed into a SOA and assisted by a Sagnac interferometer and a polarizer. In particular, the Sagnac interferometer is used to filter out the input pump and probe signals, whilst the polarizer filters the engendered signal and suppress the SOA-amplified spontaneous emission. As a result, it was obtained that for a wavelength difference as small as 0.43 nm between the pump and probe beams, the overall system output powers corresponding to the pump, probe and engendered signals were reduced approximately in 27, 29 and 29 dBm, respectively, allowing a complete filtering of the wavelength converted conjugated signal.