Abstract

Semiconductor alloys of InGaAsP are of great importance for the technology of optical communication. Relatively few experiments which measure the ultrafast response of photoexcited carriers in these materials have been reported. In this contribution, the dynamics of dense electron-hole plasmas in InGaAsP films subsequent to ultrashort optical pulse excitation are examined by probing transient transmission and reflection. Typical results are shown in Fig. 1. From the transmission data one sees short-time bleaching or gain, long-time induced absorption, and regular oscillations of the induced absorption. The oscillations are due to coherent acoustic phonon generation subsequent to relaxation of the hot, photo-excited carriers, a phenomonon that has been observed and described by Thomsen, et al, for films of a-As₂Te₃ and cis-polyacetylene.^[1] From the observation and analysis of the oscillations for the InGaAsP films, it is possible to deduce acoustic velocities and acoustic deformation potentials for these materials.

© 1985 Optical Society of America