Patent ID: 7217926

Claim:
A focal plane array (FPA) camera comprising: (I) a tunable voltage source adapted to supply a positive bias voltage and a negative bias voltage, the voltage source comprising: (IA) a positive terminal; and (IB) a negative terminal; (II) a top contact coupled to the positive terminal of the voltage source; (III) a bottom contact coupled to the negative terminal of the voltage source; (IV) a substantially-transparent substrate coupled to the bottom contact, the substantially-transparent substrate being adapted to admit light; and (V) a matrix of detectors, each detector comprising: (VA) a top surface coupled to the top contact; (VB) a bottom surface coupled to the substantially-transparent substrate, the bottom surface being substantially parallel to the top surface; (VC) side surfaces extending from the top surface to the bottom surface, each side surface being substantially non-parallel to an opposing side surface; and (VD) first-wavelength quantum-well infrared photodetector (QWIP) elements, each first-wavelength QWIP element being a first superlattice of quantum wells adapted to detect energy at a first range of wavelengths when the voltage source supplies the positive bias; and (VE) second-wavelength QWIP elements, each second-wavelength QWIP element being a second superlattice of quantum wells adapted to detect energy at a second range of wavelengths when the voltage source supplies the negative bias, the second range of wavelengths being different from the first range of wavelengths; and (VF) wherein an energy relaxation layer is interposed between the first superlattice of quantum wells and the second superlattice of quantum wells.