Self-diffraction in population gratings

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Abstract
We present a nonperturbative theory of self-diffraction in thick, pseudostationary population gratings induced by the interference of two nearly collinear incident laser beams of arbitrary relative and absolute intensities. At large saturation parameters, the grating becomes nonsinusoidal, and high-order diffraction occurs efficiently. We obtain an exact expression for the Fourier coefficients of the grating that significantly simplifies the interpretation of the various coherent coupling mechanisms and permits efficient computer simulations. In the case of small depletion of the pump waves, we obtain simple analytic expressions for the scattered intensity into any order of selfdiffraction. We present our results in a manner that should aid an experimenter in choosing the optical thickness of the unsaturated medium and the sum and ratio of the pump intensities to obtain optimum diffraction intensity in a given order.