California Institute of Technology

United States of America As Represented by the Administrator of Nasa

Sumith V Bandara

Sarath D Gunapala

John K Liu

David Z Ting

Daniel W Wilson

Cory J Hill

Kwong Kit Choi

William J Parrish

Sir B Rafol

Jason M Mumolo

An infrared detector having a hole barrier region adjacent to one side of an absorber region, an electron barrier region adjacent to the other side of the absorber region, and a semiconductor adjacent to the electron barrier.

Complementary barrier infrared detector (CBIRD)

A quantum well infrared photodetector (QWIP) focal plane array having structures, each structure having stacked layers of quantum wells and a reflective grating to provide polarization sensitivity. The reflective grating is etched to provide electrical contacts for individual pixels. The reflective gratings comprise grooves, where the grooves for a particular structure run in a particular direction to provide polarization sensitivity. Each structure may comprise groups of quantum well layers, each group sensitive to a particular frequency band. By shorting out unwanted quantum well layers, and by forming the reflective gratings to come into contact with the quantum well layers having a particular frequency band sensitivity, the pixels in the QWIP focal plane array may provide frequency and polarization information.

Polarization-sensitive quantum well infrared photodetector focal plane array

An nBn detector is described where for some embodiments the barrier layer has a concentration gradient, for some embodiments the absorption layer has a concentration gradient, and for some embodiments the absorption layer is a chirped strained layer super lattice. The use of a graded barrier or absorption layer, or the use of a chirped strained layer super lattice for the absorption layer, allows for design of the energy bands so that the valence band may be aligned across the device. Other embodiments are described and claimed.

nBn and pBp infrared detectors with graded barrier layer, graded absorption layer, or chirped strained layer super lattice absorption layer

The present invention is directed to methods of photonic crystal formation, and to methods and apparatus for using such photonic crystals, particularly in conjunction with detector arrays. Photonic crystal parameters and detector array parameters are compared to optimize the selection and orientation of a photonic crystal shape. A photonic crystal is operatively positioned relative to a plurality of light sensors. The light sensors can be separated by a pitch distance and positioned within one half of the pitch distance of an exit surface of the photonic crystals.

Ultra compact spectrometer apparatus and method using photonic crystals

Quantum-well sensors having an array of spatially separated quantum-well columns formed on a substrate. A grating can be formed increase the coupling efficiency.

Quantum well sensor having spatially separated sensing columns

Devices and techniques for coupling radiation to intraband quantum-well semiconductor sensors that are insensitive to the wavelength of the coupled radiation. At least one reflective surface is implemented in the quantum-well region to direct incident radiation towards the quantum-well layers.

Wavelength-insensitive radiation coupling for multi-quantum well sensor based on intersubband absorption

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.

Dual band QWIP focal plane array

A quantum well can be designed to detect light of a particular wavelength by tailoring the potential depth and width of the well. The design produces two energy states in the well separated by the desired photon energy. The GaAs/AlGaAs material system allows the quantum well shape to be varied over a range wide enough to enable light detection at wavelengths longer than approximately 6 &#x3bc;m. Hence, large bandgap materials such as GaAs/AlGaAs material has made fabrication of a large focal plane arrays tuned to detect light at wavelengths from 6 to 25 &#x3bc;m possible.

Broad-band quantum well infrared photodetectors

Device designs and techniques for reducing the dark current in quantum-well detectors.

Multi-quantum-well detector for low-background applications

Device designs and techniques for forming multiple-band quantum-well detectors.

Multi-quantum-well infrared sensor array in spatially-separated multi-band configuration

A three-color QWIP focal plane array is based on a GaAs/AlGaAs material system. Three-color QWIPs enable target recognition and discriminating systems to precisely obtain the temperature of two objects in the presence of a third unknown parameter. The QWIPs are designed to reduce the normal reflection over a significant wavelength range. One aspect of the present invention involves two photon absorptions per transition in a double quantum well structure which is different from typical QWIP structures. This design is expected to significantly reduce the dark current as a result of higher thermionic barriers and therefore allow the devices to operate at elevated temperatures. The device is expected to be fabricate using a GaAs/Al Ga As material system on a semi-insulating GaAs substrate by Molecular Beam Epitacy (MBE).

Three color quantum well infrared photodetector focal plane array

Techniques for coupling radiation into a quantum-well detector by using a two-dimensional array of grating cells to form at least three different grating directions to provide efficient coupling.

Growing community of inventors

Valencia, CA, United States of America

Sumith V Bandara