Pixelless imaging by transmissive quantum-well infrared photodetectors integrated with light emitting diodes

A large pixel-less thermal imager based on the epitaxial integration of GaAdAlGaAs quantum-well infirared photodetector and a GaAs light-emitting diode is demonstrated. The device transforms a mid-infixed ( 9~) scene at to a near-infrared ( 0 . 8 2~) image.The maturity of 111-V materials has been a strong incentive for the development of 111-V based infrared focal plane arrays (FPA). Today, quantum-well infiared photodetectors (QWIP) are marketed commercially. The QWIP FPA technology is based on the hybridization of a pixellated QWIP to a Si readout circuit. The hybridization for focal plane arrays is a standard technique nowadays, but this is also one of the factors for the high cost of such imagers. To circumvent the hybridization we have explored a different approach by reading the photocurrent map optically. We have proposed to put, during the epitaxial growth, a QWIP stack in series with a near-infiared light emitting diode (LED). In 1995, single QWIP-LED up-conversion elements have been demonstrated [l] and, in 1997, large area, un-pixellated devices have demonstrated upconversion of far-infiared scenes to near-infrared images which are read by a Si CCD camera [2]. Since then, the image transfer quality has been improved [3,4]. So far, only high temperature scenes could be imaged by the up-conversion technique [5]. Recently, by properly designing the grating coupler we have demonstrated the ability of QWIP-LED devices to up-convert room temperature infiared scenes to near-infrared.

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Pixelless imaging by transmissive quantum-well infrared photodetectors integrated with light emitting diodes

Cited by 2 publications

References 8 publications

Pixelless thermal imaging with integrated quantum-well infrared photodetector and light-emitting diode

Pixelless thermal imaging with integrated quantum-well infrared photodetector and light-emitting diode

Infrared thermal imaging without pixellation

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