Grating coupled intersubband transitions in microcavities

Microcavity effects can apply to intersubband transitions if the polarization selection rules are satisfied. We thus propose to insert a grating in a planar microcavity and to take advantage of both the field enhancement due to the cavity and the coupling with intersubband transitions due to the grating. The electromagnetic coupling is reinforced when both the grating and the cavity are resonant with the light wavelength. Accordingly, the spectral width is reduced where the coupling is efficient, which may provide additional advantages for some applications. Various configurations are envisioned and calculations are carried out for dielectric and metallic gratings, These architectures can be used for infrared detection, emission or modulation. Efficient and realistic devices are proposed and optimized. (C) 1996 American Institute of Physics.