Polarization-insensitive optical spectral inversion without frequency shift based on four-wave mixing in semiconductor optical amplifiers

Two schemes for polarization-insensitive optical spectral inversion without frequency shift based on four-wave mixing are proposed, both utilizing a conventional semiconductor optical amplifier (SOA) and two pump waves. The significant advantages of the configurations include their simplicity, effective suppression of the signal and one of the pump waves and a reduction in the noise associated with these polarizations. In addition, the schemes offer broad operating parameter ranges from narrow frequency detunings using short devices in one proposed configuration (type I) and wide frequency detunings using long devices in a second configuration (type II). A specific feature of the second scheme is that polarization-sensitive SOAs can be utilized without compromising the operating characteristics.