Silicon APDs for Photon Counting

The SAP-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 (V_R < V_BR) 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 SAP-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-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.