Multiple quantum well optical modulators and spatial light modulators

Abstract

This paper describes multiple quantum well (MQW) modulators and spatial light modulators (SLMs) which utilize field dependent changes in absorption, index of refraction, and polarization (birefringence). These optical parameters are changed either by band filling in quantum wells or by modifying the excitonic interaction between electrons and holes. Modulation can be achieved by impressing RF/microwave fields across MQWs in a variety of ways including direct biasing, induction by transporting charges in an adjacent channel (by charge-coupled devices, CCDs, or heterostructure acoustic charge transport, HACT), and by launching a surface acoustic wave (SAW) in a region adjoining MQWs. High contrast Fabry-Perot, birefringent, and HACT spatial light modulators are discussed in detail. One-dimensional Bragg SLMs (which use electrooptic or acoustooptic gratings) and Mach-Zehnder interferometers are also summarized.