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Common terminology in IR sensing explained: sensitivity, responsivity, and noise
Avalanche photodiode (APD) sensors used in near-infrared (NIR) systems underpin fibre-optic communications, LiDAR, medical imaging, scientific instrumentation, and many other applications. The terms sensitivity, responsivity, and noise frequently arise when discussing APD performance. These characteristics are strongly interrelated: the sensitivity of an APD is determined by how efficiently it converts light into current (responsivity) and by the degree of unwanted electrical fluctuations (noise) present in the device. To reliably detect weak optical signals requires high responsivity and low noise, which together yield the best sensitivity for real-world measurement.
Sensitivity in NIR APDs …
