Abstract

It is believed that optical computing will be able to vastly outperform electronic computing in the future. Logic gates performing data manipulations are essential building blocks of any computer. All-optical logic gates can eventually replace the electronic and electro-optic ones. We demonstrate how specific material properties can be used to construct such an all-optical logic gate based on light interaction with a nonlinear interface (NI). The NI comprises a linear dielectric material in contact with an intensity-dependent nonlinear material, which exhibits a controllable intensity-dependent reflectivity and transmissivity. We chose a material with a thermal nonlinearity that is among the largest, has a response time well suited for real-time visual demonstration, and requires a minimum of high-technology equipment. A thin film of nonlinear material is sandwiched between two identical linear materials. Both types of material have the same index of refraction for low light intensity. Absorption of light in the nonlinear medium results in heating, leading to density decrease and corresponding refractive index reduction. The angle of incidence of the air-cooled Ar⁺ laser beam is chosen so that a low-intensity light beam is transmitted, and a high-intensity light beam is totally reflected. Thus, by changing the light intensity, one controls light switching with this optical gate.

© 1990 Optical Society of America