As the SiPM photocurrent couldn't be measured directly, a new method was investigated for measuring the SiPM's PDE. To summarize, the photodiode will be used to measure the power of the white light source, which will then be converted into a number of photons per second using Equation 1:
(1),
where P is the power (W) of the white light source measured by the photodiode at a given wavelength
Then, as the photodetection efficiency is defined in Equation 2:
(2),
Equation 1 can be used to find the number of incident photons per second at a given wavelength, giving Equation 3:
(3),
where rL(λ) is the number of photons detected per second by the SiPM when illuminated by light of wavelength λ and rD(λ) is the number of photons detected per second when no light source is present (dark count rate). The photon counts per second along with the expected power must all be corrected for detector area. The rate of photons per second can be measured using the TB4 board and similar analysis to determining the dark count rate.
Photodiode active area: 1cm^2
SiPM active area: 1.33mm^2
| Figure 1: Power Spectrum Measurement |
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An integrating sphere was added to ensure area corrections could be done properly.
| Figure 2: SiPM PDE Measurement |
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An Agilent 81101A pulse generator controlled using the LabVIEW program shown in Figure 3 was used to trigger the TB4 board.
| Figure 3: LabVIEW Program |
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