Nonlinear optical effects in low-temperature-grown GaAs

GaAs semiconductor material grown at temperatures well below the normal growth temperature of 6OO C has been shown to contain an excess of As. This excess As acts to substantially reduce the carrier recombination time, and to give the material some remarkable electrical and optical properties. We have recently shown that low temperature-grown GaAs can be tailored to provide ultrashort response times for optically induced refractive index changes while exhibiting a large nonlinearity for light energies near the band edge. In fact, we have measured in this material the largest known nonlinear optical index changes with picosecond response