Infrared phototransistor validation for atmospheric remote sensing application using the Raman-shifted eye-safe aerosol lidar

The validation was performed using the Raman-shifted eye-safe aerosol lidar (REAL) at the National Center for Atmospheric Research. Although the device is optimized for detection around the 2-μm wavelength, the validation was performed at 1.543 μm, where mature commercial detectors are available.

Simultaneous measurement of the atmospheric backscatter signals using the custom-built phototransistor and commercial InGaAs avalanche photodiode indicated good agreement between both devices. The validation included detecting 11-km-range hard targets, 5-km atmospheric structure consisting of cirrus clouds, and a near-field boundary layer. Far-field low intensity and spatially narrow atmospheric features were also detectable with the new phototransistor.