Instantaneous time reversal of complex amplitude ultrafast waveforms

In this paper we report the generation of an exact time-reversed waveform when the signal contains complex amplitude information. For real-time generation of the time-reversed signal, we utilize a nonlinear wave mixing process. As with spectral holography, the wave mixing is performed with spectrally decomposed waves (the temporal frequency components of the ultrafast waveforms are spatially dispersed). The wave mixing is based on an arrangement employing cascaded second-order nonlinearities for a four-wave interaction