SWIR avalanche photodetectors (APD) utilize reverse voltage to produce an internal gain. This allows them to have a high SNR (signal-to-noise ratio) compared to PIN diodes. It also offers faster response time, better sensitivity, as well as lower current and image noise. The spectral response of APDs is also a suitable match for the SWIR range.
What’s more, the InGaAs system seems to be ideal for SWIR detectors. Namely, it provides a standard cutoff at 1,700 nm. This covers most laser emission lines at standard wavelengths. SWIR APDs utilize avalanche gain to generate signal amplification. One of the biggest advantages of this is that they allow the use of eye-safe lasers. Plus, this also results in a sensor that doesn’t require cooling.
