SOA nonlinear polarization rotation with linear polarization maintenance: Characterization and applications

We present characterization and applications of the nonlinear polarization rotation (NPR) with linear polarization maintenance arising in polarization-insensitive semiconductor optical amplifiers (SOAs). The NPR with linear polarization maintenance is characterized in terms of probe and pump power, bias current, pump polarization, as well as wavelength. The NPR with linear polarization maintenance is then exploited for simultaneous inverted and noninverted polarization-insensitive wavelength conversions (WCs) with 2R regeneration using a single polarization beam splitter (PBS). WC of 10 Gb/s with 2R regeneration is experimentally demonstrated in the whole G-band with a power penalty reduction of 1.2 dB for the inverted WC and 0.8 dB for the noninverted WC. The NPR with linear polarization maintenance is also applied to perform on-off-keying (OOK) to polarization-shift-keying (PoISK) format conversion in conjunction with WC function, where the power fluctuation caused by the SOA cross gain modulation (XGM) is successfully mitigated using two cascaded SOAs. The power fluctuation of the converted PoISK signal is reduced to less than 0.6 dB, while the extinction ratio (ER) of polarization modulation is maintained at larger than 30 dB.