When trying to detect not single photons but still very small amounts of light in the pW range, use the LCSA or LCIA series APD modules.
Equipped with low-noise Si or InGaAs avalanche photodiodes that have a preamplifier, an integrated high voltage supply, and built-in temperature compensation, these modules can be used comfortably in data transmission, laser radars, rangefinders, or biomedical systems.
All components are integrated into a small, shielded metal housing. The dimensions are just 75 mm x 56 mm x 26 mm.
Operation only requires a standard 12 VDC voltage supply, which is also available for delivery.