MICROBOLOMETER DETECTORS WITH RESONANT CAVITIES FOR ENHANCED OPTICAL ABSORPTION

A microbolometer detector for detecting electromagnetic radiation is disclosed. The microbolometer detector includes a substrate, a vacuum package, and an array of microbolometers disposed on the substrate inside the vacuum package. Each microbolometer includes a platform supported above the substrate, a thermistor disposed on the platform and having an electrical resistance that varies with its temperature, and an optical absorber including a frequency-selective surface and configured to absorb the electromagnetic radiation to generate heat and change the temperature of the thermistor. The microbolometer detector also includes a reflector disposed on the substrate under the array of microbolometers, and an optical window configured to allow the electromagnetic radiation to pass therethrough and reach the optical absorbers. The optical window is spaced apart from the reflector to form therebetween an optically resonant cavity. The resonant cavity is tuned to an absorption band of the optical absorbers.