Thorlabs offers single photon detectors and counting modules with a range of photon detection efficiencies (PDEs), detector sizes, gain options, and wavelength ranges.

The SPDMA Single Photon Detection Module, designed for use from 350 to 1100 nm, features continuously adjustable gain and an SMA electrical connector from which the TTL output can monitored by an oscilloscope or external counter. Comparatively, the SPDMHx Fixed-Gain Single Photon Detection Modules, for use from 400 to 1000 nm, combine a higher PDE in the NIR (see the graph to the right) with low maximum dark count rates; the output TTL pulses are accessible via a LEMO connector. Finally, the SPCMxxA(/M) Single Photon Counting Modules have an internal 31-bit photon counter, include a software package for controlling the detector and reading the output, and are intended for use from 350 to 900 nm.

• Single Photon Detection or Counting Modules
• Low Dark Counts
• Detector Sizes of Ø20 µm, Ø50 µm, Ø100 µm, or Ø500 µm
• Active Quenching and Temperature Stabilization

The Photon Detection Efficiency (PDE) is shown here as a function of wavelength for the SPDMA module at both Max and Min Gain, the SPDMHx modules, and the SPCMxxA(/M) modules. The operating range of the SPDMA module is 350 nm - 1100 nm, for the SPDMHx modules it is 400 nm - 1000 nm, and the operating range of the SPCMxxA(/M) modules is 350 nm - 900 nm.

Each single-photon detector or module uses a silicon avalanche photodiode. The active quenching circuit integrated into the diode of these single photon detection systems enables high count rates, allowing users to detect a photon every 35 ns - 45 ns, depending on the model chosen. The diodes are actively temperature stabilized to achieve low maximum dark count rates of 60 Hz - 1500 Hz, depending on the model and settings, with power level detection down to fW. 

Software for SPCMxxA(/M) Counting Modules

The Single Photon Counter Modules include a software package with GUI for out-of-the-box operation. The following operating modes can be set by the software:

• Manual Mode for manual operation, where the counter is started and stopped manually by pressing the Start/Stop button (toggle function).
• Free Running Timer Counter for counting incident photons for a certain number of "Time Bin Lengths."
• Externally Triggered Timer Counter for triggering the timer start for counting incident photons for a certain time period.
• Externally Triggered Counter for starting and stopping the counter by an external trigger.
• External Gating for activating the counter and the APD externally.