Abstract

To date, we have demonstrated the high-speed, high efficiency and high-repetition capabilities of a symmetric Mach-Zehnder (SMZ) all-optical switch.^1–4 As described in Refs. 1–4, this SMZ all-optical switch contains nonlinear waveguides and control pulse injection ports in both arms of a Mach-Zehnder interferometer. In each nonlinear waveguide, a control pulse excites photocarriers and induces a highly efficient nonlinear refractive index change accompanied by a band-filling effect. A signal light is switched only during the time interval between the two control pulses injected into the corresponding nonlinear waveguides. Ultrafast switching can thus be expected, although the utilized band-filling effect relaxes on a nanosecond time scale. Recently, other groups have also reported all-optical switches containing nonlinear waveguides in both arms of a Mach-Zehnder interferometer.^5–6 In the devices described in Refs, 5–6, however, the switching time is limited by the lengths of the nonlinear waveguides, because the control light and the signal light are counter-propagated in the nonlinear waveguides. This limitation in speed is not present in the SMZ all-optical switch; in this report, we experimentally demonstrate subpicosecond switching with the SMZ all-optical switch.

© 1996 Optical Society of America