Optical modulation in very thick coupled InxGa1−xAs/GaAs multiple quantum well structures

We report optical modulation results on InGaAs/GaAs coupled multiple quantum well spatial light modulators. The structure consists of an n+-GaAs buffer, an undoped 250-period coupled multiple quantum well layer, and a p+-GaAs/InAs cap. The samples are probed at room- and liquid-nitrogen temperatures using photoabsorption spectroscopy. At room temperature an absorption peak is observed at 969 nm, and this shifts to 982 nm as the field is increased from 0 to 71 kV/cm, in good agreement with theory. For a single pass through the structure, this results in a contrast ratio ≳8:1 at 969 nm. At 80 K, the contrast ratio increases to approximately 60:1 at 914 nm. A second modulator exhibits a contrast ratio ≳8:1 at 1.04 μm at room temperature.