Spectral dependence of the third-order optical nonlinearity in a bulk crystal of GaSe is studied at room temperature. The experimental techniques involved are nonlinear transmission and laser-induced self-diffraction. A theory of self-diffraction, which for the first time takes into account the multiple-beam interferences, is developed. The measurements are carried out in the spectral range around the excitonic transition of GaSe. The refractive-index changes resulting from electron–hole plasma effect contribute to the generation of a phase grating below the band gap.
© 1997 Optical Society of America
Marie May, Solange Debrus, Katarzyna Zakrzewska, Henri Benisty, and Alain Chevy, "Room-temperature optical nonlinearities in bulk GaSe," J. Opt. Soc. Am. B 14, 1048-1056 (1997)