Linear and nonlinear operation of a time-to-space processor.

The operational characteristics of a time-to-space processor based on three-wave mixing for instantaneous imaging of ultrafast waveforms are investigated. We assess the effects of various system parameters on the processor's important attributes: time window of operation and signal conversion efficiency. Both linear and nonlinear operation regimes are considered, with use of a Gaussian pulse profile and a Gaussian spatial mode model. This model enables us to define a resolution measure for the processor, which is found to be an important characteristic. When the processor is operated in the linear interaction regime, we find that the conversion efficiency of a temporal signal to a spatial image is inversely proportional to the resolution measure. In the nonlinear interaction regime, nonuniform signal conversion due to fundamental wave depletion gives rise to a phenomenon that can be used to enhanced the imaging operation. We experimentally verify this nonlinear operation.