High‐speed all‐optical switching experiment in Mach–Zehnder configuration using GaAs waveguide

We report the results of a high‐speed all‐optical switching experiment in Mach–Zehnder configuration using a GaAs waveguide. The all‐optical switching is based on the nonlinear refractive index change induced by the band‐filling effect in the GaAs waveguide. To achieve high‐speed operation without being limited by the slow carrier relaxation time, a dc electric field is externally applied to the nonlinear waveguide to sweep carriers away from the light guiding region. The FWHM (full width at half maximum) of the switching waveform without the externally applied electric field is about 800–900 ps. As the electric field is increased, the FWHM is reduced to about 80–90 ps.