Distributed Bragg Reflector Improves Photodetector

Using a distributed Bragg reflector, a new method has dramatically reduced a type of image distortion caused by spectral cross-talk between dual-band long-wavelength photodetectors.

Dual-band photodetectors provide numerous advantages in infrared imaging, including higher image quality and more data for image processing algorithms. However, spectral cross-talk interference between the two channels can limit performance, resulting in poor spectral contrast and preventing infrared camera technology from reaching its full potential.

The findings pave the way for developing a new generation of high spectral-contrast infrared imaging devices with applications in medicine, defense and security, planetary sciences, and art preservation.

Dual-band imaging makes objects visible in multiple wavelength channels using a single infrared camera. For example, in night-vision cameras, dual-band detection can help the wearer distinguish between moving targets and objects in the background.

The absorption of a portion of the light from one wavelength channel by the second is called spectral cross-talk. As detection wavelengths lengthen, the problem becomes more severe.

To counteract this, the researchers created a new version of a distributed Bragg reflector (DBR), a highly-refractive, layered material placed between the two wavelengths’ channels. The DBR structure divided the two channels in an antimonide type II superlattice photodetector.

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