Method for characterizing single photon detectors in saturation regime by cw laser

Area of Science:

• Photonics and Optical Engineering
• Quantum Optics
• Detector Physics

Background:

• Accurate modeling of single photon detectors (SPDs) is crucial for quantum information processing and low-light imaging.
• Existing models often fail to account for afterpulsing effects across a wide range of optical power.
• Afterpulsing, where a previous detection event triggers a false detection, significantly impacts SPD performance.

Purpose of the Study:

• To derive a comprehensive analytical expression for the count probability of an SPD.
• To incorporate the effects of afterpulsing into the count probability model.
• To validate the derived expression using experimental data from a commercial SPD.

Main Methods:

• Derivation of an analytical model for SPD count probability.
• Inclusion of an afterpulsing term within the probability expression.
• Experimental validation using a saturated commercial SPD illuminated by a continuous-wave (cw) laser.

Main Results:

• An analytical expression accurately describing SPD count probability was successfully derived.
• The model effectively accounts for afterpulsing effects over a broad range of input optical power.
• Fitting the model to experimental data yielded detector efficiency and afterpulsing probability values consistent with manufacturer specifications at low repetition frequencies.

Conclusions:

• The developed analytical expression provides a robust tool for characterizing SPD performance.
• The model's validity is confirmed by its agreement with experimental data, particularly regarding efficiency and afterpulsing.
• This work offers improved accuracy for SPD performance analysis, especially in scenarios with significant afterpulsing.