Phase-modulation-induced two-wave mixing in semiconductors

Two-wave mixing amplification of a weak probe beam interfering with a powerful pump beam of the same Linear polarization is demonstrated when the probe beam enters the semiconductor sample before the pump pulse. This mixing of two beams of the same frequency is made possible by the difference between self-phase modulation and cross-phase modulation, which modify differently the instantaneous frequencies of both beams. Net gain coefficients up to 5.5 cm(-1) are obtained for experiments performed in CdTe. Theoretical calculations quantitatively confirm this interpretation and predict much higher gain for more resonant configurations or higher pump energies, making this process of potential interest for optical processing. (C) 1997 Optical Society of America.