For applications that require highest sensitivity. The APD Avalanche photodiodes can provide an extremely sensitive alternative to traditional PIN photodiodes. The APD is sensitive and fast enough for the characterization of, for example, pulsed solid-state lasers on the nanosecond scale. It maintains high gain stability over a 10°C to 40°C temperature range by utilizing a temperature compensation circuit which adjusts the ~150 VDC bias to insure operation near the breakdown voltage.