Si APDs

Silicon avalanche photodiodes are used in the wavelength range between 250 nm and 1100 nm. The avalanche effect of these photodiodes makes them well suited for the detection of extremely weak light intensities.

Silicon APDs for Photon Counting

The SAP-series silicon avalanche photodiodes are primarily used in photon counting. This series features highest efficiency and lowest dark current rates.

Si APDs

The SAP series

The SAP500 series is based on a "reach through” structure with excellent quantum efficiency as well as extremely low noise and dark current. This APD, which has an active area of D=500 µm, can either be operated in normal linear mode (VR < VBR) with an internal gain of 250 or more or in "Geiger” mode.

In "Geiger” mode the APD is operated at a voltage that is larger than the breakdown voltage (VR > VBR); in this mode, single photons can be detected.

Applications

The new SAP500 series is well suited for applications that quantify the weakest light signals (including single photons) and detect them in a time-resolved manner (e.g., LIDAR, spectroscopy, fluorescence measurements, or photon counting). The advantages compared to photomultipliers (PMTs) are as follows:

Small compact design
Very high quantum efficiency
Not sensitive to magnetic fields
Robust
Long lifetime
Very good time resolution
Inexpensive
Smaller operating voltage

The SAP-500 series is available in a modified, hermetically-sealed TO-46 housing. A version is also available with a single-stage thermoelectric cooler in a TO-37 housing or a double-stage TEC in a TO-8 housing.