Long-range surface plasmon electrooptic modulator.

An electrooptic modulator based on electrically varying the degree of coupling of a light beam to a long-range surface plasmon excitation is modeled. A specific embodiment of a modulator is shown to be capable of changing its reflectance from 0.00 to 0.84 on the application of 100 V across a 1-microm thick electrooptic film with a second-order susceptibility of 2 x 10(-7) esu. The affect that the width of the long-range surface plasmon excitation resonance has on the performance of the modulator is considered. Plane-wave calculations show that decreasing the width of the resonance increases the amount of modulation possible for a given voltage change. More realistic calculations which take into account diffraction of a beam of finite width show that a decrease in resonance width can in some cases degrade device performance.