The optical sensitivity of SiPM is typically given by the photon detection efficiency (PDE), which is the ratio of detected photo-electrons and the number of incident photons. This value can be used to calculate the responsivity of the sensor by the following equation:

    \[ {\mathrm{R}= \frac{\mathrm{PDE} \cdot \lambda \cdot \mathrm{G} \cdot e \cdot (1+\mathrm{P_{AP}}) \cdot (1+\mathrm{P_{XT}})}{h \cdot c \cdot 100\%}} \]

  • \mathrm{PDE} = Photon Detection Efficiency
  • \lambda= Wavelength
  • \mathrm{G} = Gain
  • \mathrm{e} = Electron Charge
  • \mathrm{P_{AP}} = Afterpulsing Probability
  • \mathrm{P_{XT}} = Crosstalk Probability
  • h = Planck Constant
  • c = Speed of light