Patent ID: 6897447

Claim:
A multi-spectral infrared radiation photodetector comprising: a plurality of elongate infrared radiation absorbing elements for absorbing at least two bands of infrared radiation, each of the plurality of elements having first and second opposite longitudinal surfaces, the at least two bands of infrared radiation incident upon the first surfaces of the plurality of elements; a plurality of electrically interconnected strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a reflector for the at least two bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity for the at least two bands of infrared radiation, and wherein a ratio between a photoresponse to each of the at least two bands of infrared radiation is a function of an external bias applied between the plurality of strips and the bottom contact.