THEORY OF AND EXPERIMENT WITH THE ELECTROOPTIC EFFECT IN INTERNAL-REFLECTION NEAR THE CRITICAL ANGLE

The electro-optic effect in intemal reflection near the critical angle can directly modulate the reflectance of anoptical beam with microwav e electrical signals. The measured change in reflectance is 1.3 x 10(- 6) V(rms)-1 cm for each applied microwave electric field, and modulati on has been detected with input microwave signals as small as 10 mV(rm s). We present the theoretical explanation of this interaction in two complementary pictures, one picture based on nonlinear-optical theory and one based on electro-optics. Our experiments with fundamental opti cal and electrical properties match the predictions of both theories. The most salient feature of the electro-optic effect in internal refle ction is that the strength of the modulation peaks sharply at the crit ical angle.