Avalanche Current Waveform Estimated From Electroluminescence in InGaAs/InP SPADs

We demonstrated that the avalanche current waveform in InGaAs/InP single-photon avalanche diodes (SPADs) can be estimated from the measurement of the electroluminescence emitted by the SPAD itself. We simultaneously acquired and compared both optical and electrical waveforms and we extracted the dependence of avalanche current on electroluminescence, showing that the number of collected photons is almost proportional to the number of carriers flowing through the p-n junction, whereas the excess bias (that sets the electric field in the multiplication region when the avalanche is triggered) has a negligible impact. This non-invasive optical technique for estimating the avalanche current can be used when the electrical measurements of the SPAD current are not feasible.