Photon Detection Efficiency Calculator (SiPM)

Created by Dominik Czernia, PhD
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Feb 13, 2023

The photon detection efficiency calculator is designed to minimize the time spent on laborious calculations concerning Silicon Photomultipliers (SiPM). SiPMs are novel silicon detectors that are capable of detecting faint and fast light signals, even at a single photon level. Because of their high gain and quick response, they may find future applications in medical imaging, e.g., Positron Emission Tomography (PET) or Single-Photon Emission Computed Tomography (SPECT). SiPMs are also compact and compatible with magnetic resonance devices.

We have prepared a tool to quickly switch between a photon's energy, frequency, and wavelength. Check the photon energy calculator if you need to analyze this quantum of the electromagnetic field!

Photon detection efficiency formula

The photon detection efficiency PDE is a quantity that measures the sensitivity of SiPMs. You can easily calculate it from the responsivity, R, of the sensor – with responsivity being the average photocurrent produced per unit of optical power. To make the conversion from R to PDE, you can use the following photon detection efficiency formula:

PDE=RhceλG(1+PXT)(1+PAP)\small {\rm PDE} = \frac{Rhc}{{\rm e}\lambda G (1 + P_{\rm XT})(1 + P_{\rm AP})}


  • PDE\rm PDE – Photon detection efficiency;
  • RR – Responsivity, expressed in amps per Watt A/W;
  • h=6.626×1034 m2kg/sh = 6.626 \times 10^{-34}\rm\ m^2·kg/s is Planck's constant;
  • c=2.998×108 m/sc = 2.998 \times 10^8\rm\ m/s is the speed of light;
  • e=1.602×1019 Ce = 1.602 \times 10^{-19}\rm\ C is elementary charge;
  • λ\lambda – Wavelength of the incident light;
  • GG – Gain, i.e., the amount of charge created for each detected photon;
  • PXTP_{\rm XT} – Crosstalk probability; and
  • PAPP_{\rm AP} – Afterpulsing probability.

To accurately determine PDE, you should always take into account contributions due to optical crosstalk and afterpulsing. The former occurs when a single incident photon generates signals equivalent to two or more photons. The latter happens when some carriers become trapped in defects in the silicon. After some time, up to several nanoseconds, they are released, creating an additional signal. You can determine the probability of both phenomena separately by taking the appropriate measurements.

The intrinsic carrier concentration calculator might be a helpful tool if you need to investigate this physical quantity. Intrinsic carrier concentration is a crucial parameter to consider for photoactive materials.

Photon detection efficiency calculator – an example

This photon detection efficiency calculator is straightforward to use and will calculate any missing variable if all of the others are provided. Simply enter any five quantities, and the sixth will be automatically estimated. For example, let's find out what the PDE of a SiPM with the following parameters will be:

  • gain G = 1,000,000
  • crosstalk probability P_XT = 20%
  • afterpulsing probability P_AP = 4%

Let the incident light's wavelength be λ = 420 nm and the responsivity R = 150,000. What is the photon detection efficiency? Fill in the appropriate fields, and you'll find that PDE = 35.48%. Isn't that simple with the photon detection efficiency calculator?

Are you interested in electronics? Check out our other exciting calculators! Visit the Shockley diode calculator to analyze the electrical properties of a real diode or the drift velocity calculator to find out how fast electricity travels.

Dominik Czernia, PhD
Gain (G)
Afterpulsing probability
Crosstalk probability
Wavelength (λ)
Responsivity (R)
Photon Detection Efficiency (PDE)
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