Phenomenological model analysis for semiconductor optical amplifiers and application to time-domain digital polarization encoding

We propose and demonstrate that semiconductor optical amplifiers (SOAs) for each wavelength of the input can be described by a lumped-elements sequence of a partly linear polarizer and a retarder followed by a polarization-independent amplifier, and further obtain two necessary conditions for the valuable orthogonal polarization rotation (OPR), which will be instructive for SOA-based all-optical signal processing. Subsequently we implement photoinduced OPR by controlling an similar to 2.5 mW pump laser and find the optimal pump,wavelength should be an similar to 0.4 nm interval around the central wavelength of the probe laser. Therefore we propose a time-domain digital polarization encoding scheme based on photoioduced OPR with cross-gain modulation in a SOA and perform it well in a 15 km single-mode-fiber system at 2.5 Gbits/s, which is applicable to optical-power-equalized fiber communication. (C) 2008 Optical Society of America