Multicolor infrared focal plane arrays

Abstract

The multicolor focal plane array of this invention detects and distinguishes between incoming electromagnetic radiation within a first band of wavelengths and incoming electromagnetic radiation within a second band of wavelengths which includes the first wavelength band. The array includes a substrate and a two dimensional array of detectors disposed on the substrate and responsive to electromagnetic radiation within a predetermined range of wavelengths including the first and second wavelength bands. A first thin film filter is disposed on the substrate and interposed between the incoming radiation and a subset of the detectors in the array to prevent radiation outside of the first wavlength band from reaching the detectors. A second thin film filter is disposed on the substrate and interposed between the incoming radiation and all of the detectors in the array to prevent radiation outside of the second wavelength band from reaching the detectors in the subset. The filter design uses a double optimized approach that effectively reduces the thickness of the multilayer stack requiring lithographic patterning. A thickness of less than five microns is achieved which enables the use of a multilayer resist lift-off method. The detectors in the subset are thus made sensitive to wavelengths within the first wavelength band, while the remaining detectors are sensitive to wavelengths within both the first and second wavelength bands.

Dependencies are inferred from the claim text.