Plasmonic micro-disk cavity quantum well infrared photodetectors

A subwavelength-in-thickness three-layer (gold micro-disk/quantum well infrared photodetector (QWIP)/metal reflector, MIM) plasmonic micro-cavity structure has been developed as a coupling resonator to enhance the photo-responsivity of the QWIP. The disk cavity structure captures and confines the incident light at the resonant wavelengths due to the near-field plasmonic effect. Comparing with the reference 45-degree edge-coupled device from the same wafer, the responsivity has been promoted by a factor of 3.3. By carefully selecting the resonant order, this micro-disk MIM plasmonic structure is very much helpful for reducing the pixel size for high definition focal plane arrays.