Penalty-free polarization insensitive wavelength conversion using bidirectional four-wave mixing in a single semiconductor optical amplifier

Four-wave mixing (FWM) in Semiconductor Optical Amplifiers (SOAs) has been extensively investigated for a number of applications in optical communications. The strong polarization sensitivity of the mixing process is, however, a major issue in the utilization of the FWM technique in practical networks. Several schemes for polarization insensitive FWM in SOAs have been demonstrated, which utilise rather complex configurations involving several optical components. Recently, we proposed an extremely simple scheme for polarization insensitive FWM, utilizing just one polarization insensitive SOA and one pump wave. Furthermore, employing two pump sources in the scheme, polarization insensitive and frequency-conversion frequency-interval independent FWM can be also obtained. In all the aforementioned configurations, polarization insensitive SOAs were employed to achieve the polarization insensitive FWM performance. In this paper, we will show that polarization insensitive FWM operation can also be realised, using a polarization sensitive SOA by modifying the configuration