Abstract: A photo detection device comprising a contact layer through which light enters; an absorbing region positioned such that light admitted through the contact layer passes into the absorbing region; at least one diffractive element operatively associated with the absorbing region operating to diffract light into the absorbing region; the configuration of the at least one diffractive element being determined by computer simulation to determine an optimal diffractive element (or elements) and absorbing region configuration for optimal quantum efficiency for at least one predetermined wavelength detection range, the at least one diffractive element operating to diffract light entering through the contact layer such that phases of diffracted waves from locations within the photo detection device or waves reflected by sidewalls and waves reflected by the at least one diffractive element form a constructive interference pattern inside the absorbing region.

Abstract: A photodetector comprising a contact layer; an absorbing region positioned such that light admitted passes into the absorbing region; a diffractive region comprising at least one diffractive element operating to diffract light into the absorbing region; the configuration of the photodetector being determined by computer simulation to determine an optimal diffractive region and absorbing region configuration for optimal quantum efficiency for at least one predetermined wavelength range, the diffractive region operating to diffract light entering through the contact layer such that phases of diffracted waves from locations within the photodetector including waves reflected by sidewalls and waves reflected by the diffractive elements form a constructive interference pattern inside the absorbing region.

Abstract: A photo detection device comprising a contact layer through which light enters; an absorbing region positioned such that light admitted through the contact layer passes into the absorbing region; at least one diffractive element operatively associated with the absorbing region operating to diffract light into the absorbing region; the configuration of the at least one diffractive element being determined by computer simulation to determine an optimal diffractive element (or elements) and absorbing region configuration for optimal quantum efficiency for at least one predetermined wavelength detection range, the at least one diffractive element operating to diffract light entering through the contact layer such that phases of diffracted waves from locations within the photo detection device or waves reflected by sidewalls and waves reflected by the at least one diffractive element form a constructive interference pattern inside the absorbing region.

Abstract: A photodetector comprising a contact layer; an absorbing region positioned such that light admitted passes into the absorbing region; a diffractive region comprising at least one diffractive element operating to diffract light into the absorbing region; the configuration of the photodetector being determined by computer simulation to determine an optimal diffractive region and absorbing region configuration for optimal quantum efficiency for at least one predetermined wavelength range, the diffractive region operating to diffract light entering through the contact layer such that phases of diffracted waves from locations within the photodetector including waves reflected by sidewalls and waves reflected by the diffractive elements form a constructive interference pattern inside the absorbing region.

Abstract: A method for designing a photodetector comprising an array of pixels: selecting at a material composition for the photodetector; determining a configuration of at least one pixel in the array of pixels using a computer simulation, each pixel comprising an active region and a diffractive region, and a photodetector/air interface through which light enters, the computer simulation operating to process different configurations of the pixel to determine an optimal configuration for a predetermined wavelength or wavelength range occurring when waves reflected by the diffractive element form a constructive interference pattern inside the active region to thereby increase the quantum efficiency of the photodetector. An infrared photodetector produced by the method.

Abstract: An infrared photodetector comprising: a thin contact layer substantially transparent to infrared light; an absorption layer positioned such that light admitted through the substantially transparent thin contact area passes through the absorption layer; the absorption layer being configured to utilize resonance to increase absorption efficiency; at least one reflective side wall adjacent to the absorption layer being substantially non-parallel to the incident light operating to reflect light into the absorption layer for absorption of infrared radiation; and a top contact layer positioned adjacent to the active layer.

Abstract: An infrared photodetector comprising: a thin contact layer substantially transparent to infrared light; an absorption layer positioned such that light admitted through the substantially transparent thin contact area passes through the absorption layer; the absorption layer being configured to utilize resonance to increase absorption efficiency; at least one reflective side wall adjacent to the absorption layer being substantially non-parallel to the incident light operating to reflect light into the absorption layer for absorption of infrared radiation; and a top contact layer positioned adjacent to the active layer.

Abstract: An infrared photodetector comprising a thin contact layer substantially transparent to infrared light; an absorption layer positioned such that light admitted through the substantially transparent thin contact area passes through the absorption layer; the absorption layer being configured to utilize resonance to increase absorption efficiency; at least one reflective side wall adjacent to the absorption layer; the at least one reflective side wall being substantially non-parallel to the incident light; the at least one sidewall operating to reflect light into the absorption layer for absorption of infrared radiation; a top contact layer positioned adjacent to the active layer.

Abstract: A quantum well infrared photodetector comprising a tunable voltage source; first and second contacts operatively connected to the tunable voltage source; a substantially-transparent substrate adapted to admit light; first and second layers operatively connected to the first and second contacts; a quantum well layer positioned between the first and second layers; light admitted through the substantially transparent substrate entering at least one of the first and second layers and passing through the quantum well layer; at least one side wall adjacent to at least one of the first and second layers and the quantum well layer; the at least one side wall being substantially non-parallel to the incident light; the at least one sidewall comprising reflective layer which reflects light into the quantum well layer for absorption.

Abstract: The present disclosure relates to detection of light (or radiation) at different wavelengths. A voltage-tunable multi-color infrared (IR) detector element receives incident radiation through a substantially-transparent substrate. Side surfaces of the voltage-tunable multi-color IR detector element reflect the incident radiation, thereby redirecting the radiation. The reflected radiation is directed through a voltage-tunable multi-color infrared (IR) detector. Energy proportional to different ranges of wavelengths is detected by supplying different bias voltages across the voltage-tunable multi-color IR detector element.

Abstract: A plurality of quantum-grid infrared photodetector (QGIP) elements are concatenated to form a spectrometer. Each of the QGIP elements is adapted to detect light at a particular range of wavelengths. Additionally, each QGIP element is adapted to produce a photocurrent that is proportional to the amount of light detected at its respective range of wavelengths. This type of configuration permits spectrometry within a spectrum that spans the aggregate ranges of wavelengths of each QGIP element.

Abstract: A quantum well infrared photodetector (QWIP) that provides two-color image sensing. Two different quantum wells are configured to absorb two different wavelengths. The QWIPs are arrayed in a focal plane array (FPA). The two-color QWIPs are selected for readout by selective electrical contact with the two different QWIPs or by the use of two different wavelength sensitive gratings.

Abstract: A quantum well infrared photodetector (QWIP) that provides two-color image sensing. Two different quantum wells are configured to absorb two different wavelengths. The QWIPs are arrayed in a focal plane array (FPA). The two-color QWIPs are selected for readout by selective electrical contact with the two different QWIPs or by the use of two different wavelength sensitive gratings.

Abstract: A polarization-sensitive infrared (IR) detector array for use in infrared cameras and other IR based instruments, is comprised of multiple corrugated quantum well infrared photodetector elements (C-QWIP) that form a unitary detector unit (cell). The array is preferably two-dimensional, which can detect polarization contrast of an observed object in a scene. Each detector unit (cell) is formed by a group of C-QWIP detector elements having different groove orientations and cross sections. Each detector unit (cell) has at least two C-QWIP detector elements with their respective corrugations orthogonally oriented. Infrared detection by these detector cells is primarily by polarization contrast, compared to intensity contrast, which is well known in the art. By measuring polarization of reflected light from the observed object, the type of material can also be identified. A first array embodiment of the invention comprises four C-QWIP elements that form a cell.

Abstract: A quantum grid infrared photodetector (QGIP) includes a semiconductor substrate with a quantum well infrared photodetector (QWIP) mounted thereon. The QWIP includes a lower contact layer formed on a planar surface of the substrate and a stack of alternate planar barrier layers and planar well layers sandwiched between the lower contact layer and an upper contact layer. The planes of the barrier layers and well layers are substantially parallel to the plane of the planar surface. A plurality of single-slit diffraction units are arranged as a grid in the stack for diffracting incident infrared radiation into a continuum of radiation components directed toward the well layers at different angles with respect to the planes of the well layers. The diffraction units are composed of cavities that extend through the barrier layers, the well layers and the upper contact layer. The cavities have rectangular, square and round shapes and are arranged in rows and columns to form the grid.

Abstract: A semiconductor infrared detector having a transistor structure with a superlattice base. The superlattice base is between a multiple quantum well (MQW) structure and an electron energy high pass filter. The superlattice base restricts electrons to minibands resulting in no overlap in energy between the energies of the photoelectrons and the dark electrons. As a result, more photoelectrons reach the collector, and the emitter to collector photocurrent transfer ratio is increased. The increased transfer ratio results in increased sensitivity of the detector. The superlattice base between the MQW structure and the electron energy high pass filter comprises multiple alternating wells and barriers. The wells are preferably made of GaAs and the barriers are preferably made of Al.sub.x Ga.sub.1-x As, where x is equal to 0.25.

Abstract: A tunable radiation detector comprises a superlattice structure having a rality of quantum well units each separated by a first potential barrier and each having at least two doped quantum wells separated by a second potential barrier. The wells each have a lower energy level and a higher energy level. The first potential barriers substantially impede electrons at the lower levels from tunneling therethrough. The second potential barriers permit electrons at the lower levels to tunnel therethrough and prevent energy-level coupling between adjacent ones of the doped quantum wells. A biasing circuit is connected across the semiconductor superlattice structure. A photocurrent sensor is provided for measuring the amount of radiation absorbed by the semiconductor superlattice structure. The superlattice structure is made a part of a hot-electron transistor for providing amplification.

Abstract: A circuit incorporating an infrared hot electron transistor having a common base and biasing voltages. In one embodiment, the circuit is configured to take advantage of the photovoltage amplification capabilities of the infrared hot electron transistor. In another embodiment, the infrared hot electron transistor is configured to take advantage of the photovoltaic mode of operation of the infrared hot electron transistor. The present invention can therefore be used to directly replace a photodiode used in infrared detection. The present invention additionally provides an amplified output voltage and permits direct DC coupling to a high gain operational amplifier.

Abstract: A high-speed semiconductor device which comprises an emitter layer, a base layer, a collector layer, a potential barrier layer disposed between the emitter layer and the base layer, and a superlattice disposed between the base layer and the collector layer. The superlattice provides a multitude of quantum-mechanical transmission coefficients which can be applied to linear analog circuits and high frequency circuit. In addition, the high speed semiconductor device may act as a frequency multiplier, providing an output signal having 2n times as many frequencies as an input signal when n is the number of energy pass bands in said superlattice below a predetermined applied voltage.

Abstract: A multicolor .[.infrared.]. detection device comprising a number of doped antum well structural units. Each unit consists of a thick well and a thin well separated by a thin barrier. This arrangement produces strong coupling. .[.Infrared radiation.]. .Iadd.Radiation .Iaddend.incident on the device gives rise to intersubband absorption. For each transition a photosignal results which allows the detection of a plurality of incident frequencies.