Gated InGaAs Detector Characterization with Sub-Picosecond Weak Coherent Pulses

TL;DR

This paper introduces a method to characterize gated InGaAs single-photon detectors using ultrashort weak coherent pulses, enabling measurement of detection probabilities, afterpulse behavior, and timing jitter with high precision.

Contribution

The study presents a novel characterization technique employing sub-picosecond pulses to analyze detector parameters and afterpulse dynamics in InGaAs SPDs.

Findings

Estimated a 2.1 microsecond half-life for trapped carriers.

Quantified the detector's timing jitter as 55 ps.

Demonstrated uneven detection probabilities within the gate window.

Abstract

We propose and demonstrate a method to characterize a gated InGaAs single-photon detector (SPD). Ultrashort weak coherent pulses, from a mode-locked sub-picosecond pulsed laser, were used to measure photon counts, at varying arrival times relative to the start of the SPD gate voltage. The uneven detection probabilities within the gate window were used to estimate the afterpulse probability with respect to various detector parameters: excess bias, width of gate window and hold-off time. We estimated a lifetime of 2.1 microseconds for the half-life of trapped carriers, using a power-law fit to the decay in afterpulse probability. Finally, we quantify the timing jitter of the SPD using a time to digital converter with a resolution of 55 ps.