Non-uniform Transient Gratings Induced by Laser Pulses in Nonlinear Media

Abstract

The excitation of transient gratings induced by the interference of two equal parts of a short laser pulse in nonlinear media with one- or two-photon absorption is considered. The pulse-induced grating displays completely the pulse self-interference pattern; it is not periodic but has the form of a spatially non-uniform permittivity stratification. The grating amplitudes are described by pulse correlation functions. They contain information on the pulse shape and are sensitive to its phase modulation. The diffraction efficiency of the induced grating is calculated using electrodynamic perturbation theory. It is shown that the measurement of the spectral or angular distribution of the diffracted probe light enables the grating amplitude to be computed. The correlation functions of individual pulses can be determined in this way. Some applications of the pulse-induced gratings are proposed, as is a simplified technique for measuring the pulse width. The practicability of the grating in real nonlinear media is estimated.