Transient Grating Spectroscopy of LaP₅O₁₄: Nd³⁺

Degenerate four-wave mixing spectroscopy is used to measure the diffusion of electronic excitation in the system Nd_xLa_{(1 - x)}P₅O₁₄. For samples with x= 0.2, 0.5, and 1.0, diffusion lengths of 165, 242, and 253 nm were obtained. When the period of the grating is less than 1.3, µm and greater than 2.2 µm, the observed scattered beam decay exhibits unusual features which are discussed in terms of excitation trapping and the influence of other types of laser-induced grating phenomena.