Abstract

We demonstrate a novel InSb optical switch that relies on an increasing absorption mechanism and uses only surface reflection. We have observed of external switching of the reflectivity of the InSb surface using a pump beam from a pulsed CO₂ laser. The polarity of the switched-out signal was found to depend on the wavelength of the probe beam. For the same samples and the same experimental setup, all reflected signals from the visible probe beam were positive, whereas the signals switched out from near-infrared light were negative. We propose that this potentially useful effect is based on positive feedback in which the increasing absorption increases the local InSb temperature. The thermal coefficient of the refractive index also depends on the wavelength of radiation. This spectral-dependence effect has been applied to demonstrate optical AND, NAND, and NOR gates by using configurations of one probe with both one and two pump beams. The external switching of the surface reflection also exhibits the potential for parallel optical processing. Based on one pump beam, two probe beams with different wavelengths have been modulated simultaneously.

© 1990 Optical Society of America