HETERODYNE PUMP PROBE TECHNIQUE FOR TIME-DOMAIN STUDIES OF OPTICAL NONLINEARITIES IN WAVE-GUIDES

We describe a novel pump-probe technique in which pump and probe pulses are collinear and have parallel polarizations but are still distinguishable. This new technique is especially useful for femtosecond time-domain studies of waveguides. We present experimental results for bulk (V-groove) semiconductor optical amplifiers at 1.5-mu-m and compare them with results for orthogonally polarized pump-probe measurements. The comparison demonstrates differences that are due to anisotropy of the group velocity as well as of the waveguide nonlinearity.