Femtosecond Dynamics of the Nonlinear Index Near the Band Edge in AlGaAsWaveguides

摘要

The transient behavior of the nonresonant nonlinear index is investigated inAlGaAs waveguides with femtosecond time resolution. Both the refractive index and the absorption changes are measured by time division interferometry and pump probe techniques. Different mechanisms which contribute to the nonlinear index are distinguished by examining their dynamics, including the optical Stark effect, resonantly excited carriers, and two-photon absorption processes. The relative contribution from each mechanism is a strong function of wavelength near the band edge. Studies of nonlinear optical properties of semiconductors near the band edge provide essential information for the development of optical and electro-optical switching devices. Reprints. (JES)