Optical coupling mechanisms in Quantum Well Infrared Photodetectors

Light coupling systems, such as gratings are required because Quantum Well Infrared Photodetectors do not respond to normal incident light due to the quantum mechanical selection rules associated with intersubband transitions. The resolution of the photolithography and accuracy of the etching become key issues in producing smaller,orating feature sizes especially in shorter wavelengths. An enhancement factor of three due to 2D periodic,orating fabricated on a QWIP structure was observed. Variation of the enhancement factor with groove depth and feature size of the grating can be theoretically explained.