Dynamic holographic phase gratings in multiple-quantum-well asymmetric Fabry-Perot reflection modulators

Dynamic holographic pi-phase gratings can be written in a multiple-quantum-well asymmetric Fabry-Perot reflection modulator by spatial modulation of the quantum-confined exciton absorption. Operating near the Fabry-Perot resonance, the phase grating quenches the zero-order reflection and enhances the first-order diffraction efficiency. The diffraction efficiency of these structures as diffractive optics elements is not sensitive to the contrast ratio, which eases the constraints for device fabrication. Numerical simulations for multiple-quantum-well structures are presented that fully include refractive-index changes in response to a spatial modulation of the exciton absorption, which can be caused by any of several techniques, including free-carrier gratings, absorption bleaching, electro-optic effects, and photorefractive effects.