Multiple quantum well spatial light modulators for optical processing

Recent theoretical and experimental work in the area of multiple quantum well (MQW) modulators for optical processing applications is presented. The theoretical work includes the application of the effective mass approximation to compositional MQW structures and the use of a two-band tight-binding approximation to doping-modulated nipi structures. The theoretical calculations are used to obtain electric-field-dependent absorption and refractive index in the above MQW structures. The experimental results of a 4-microns thick GaAs/GaAlAs MQW modulator show an about 10:1 on/off ratio with an applied voltage of about 20 V (absorption change of about 6000/cm at E of about 50 kV/cm) and about 0.4 pi rad of phase shift with an applied voltage of about 10 V. Such high electro-optical modulations have previously been reported only in the MQW optical waveguide modulator. Concepts of photoactivated, electrically addressed MQW spatial light modulators and IR-to-visible MQW spatial light modulators are presented. Finally, theoretical evaluation of quantum dot arrays and their potential use in spatial light modulators are discussed.