POLARIZATION-INSENSITIVE 4-WAVE-MIXING IN A SEMICONDUCTOR OPTICAL AMPLIFIER

We propose and demonstrate a method to obtain polarization-insensitive four-wave mixing in a semiconductor optical amplifier. The method mak es use of two pumps with orthogonal polarization placed at the two sid es of the signal spectrum. Unlike a previously proposed scheme, a larg e bandwidth of the signal does not set a lower limit to the degree of polarization insensitivity obtained. Using a commercially available pi g-tailed semiconductor optical amplifier, we have obtained less than 0 .4 dB of intensity variation of the conjugate field for arbitrary chan ges of the signal polarization. (C) 1998 American Institute of Physics .