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 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.
