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Understanding APD noise and sensitivity
Avalanche photodiodes (APDs) convert light into electrical current. They are widely used in applications where high sensitivity and fast response are required, such as in fibre optic communication systems, laser rangefinders, LiDAR, and optical test equipment.
APDs exhibit internal gain through a process called avalanche multiplication. An applied reverse voltage generates a strong electric field across the diodes’ PN junctions. The generated electrons and holes are accelerated by this electric field. As these carriers move, they gain enough kinetic energy to ionise other atoms in the semiconductor material, creating more electron-hole pairs.The avalanche gain mechanism in APDs …
