Differential heterodyne detection with diffractive optics for multidimensional transient-grating spectroscopy

Abstract

Heterodyne detection with a local oscillator generated by a diffractive optic provides good phase stability, but suffers from interfering single-beam-bleach signals. This interference is a problem in four-beam transient gratings, but becomes more severe in higher order transient gratings. A simple and low noise method to eliminate this interference is demonstrated in both a four-wave-mixing, first-order-transient-grating experiment and in a six-wave-mixing, second-order-transient-grating experiment.