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 c onventional semiconductor optical amplifier (SOA) and two pump waves. The s ignificant advantages of the configurations include their simplicity, effec tive suppression of the signal and one of the pump waves and a reduction in the noise associated with these polarizations. In addition, the schemes of fer broad operating parameter ranges from narrow frequency detunings using short devices in one proposed configuration (type I) and wide frequency det unings using long devices in a second configuration (type II). A specific f eature of the second scheme is that polarization-sensitive SOAs can be util ized without compromising the operating characteristics.