High contrast Fabry–Perot optical modulator using quantum confined Stark effect tuning in InGaAs‐GaAs multiple quantum well cavity

Tunable Fabry–Perot modulators, consisting of strained InGaAs‐GaAs multiple quantum well (MQW) layers, have been shown to yield a contrast over 1200:1. Tuning is achieved by varying the index of refraction of the MQW layers forming the cavity using a quantum confined Stark effect. The mirrors are realized by AlAs‐GaAs quarter wave λ/4 dielectric stacks having 12 and 15.5 periods, respectively. The device has the potential of achieving even higher tunable contrast ratios when the number of periods of the λ/4 mirrors are increased. A contrast ratio of 6000:1 has been achieved for a nontunable structure. Measured data on optical transmission and contrast ratio are presented for various wavelengths as a function of applied bias. Results of simulation of transmitted output are also discussed.