Microcavity enhanced Stark optical modulator for long-wave infrared

A voltage-tunable microcavity modulator is designed, fabricated and characterized. The device active area comprises a stack of type II metamorphic quantum wells (QW) sandwiched between doped contact layers that also serve as optical mirrors. The device operates in the spectral region of 8-16 mu m. The optical transmission of the cavity can be modulated in a range of similar to 2% at a wavelength of 9.5 mu m by application of a bias voltage with an amplitude of 4 V. The sign of the transmission change depends on the voltage polarity as expected from the first order Stark effect in the polar type-II QWs. This results in a two times higher transmission modulation amplitude at a given voltage compared with type I quantum wells and bulk materials.