Fig. 1. Simplified circuit for the SPAD detector with temperature controlling. SPAD, single-photon avalanche photodiode; CO, the ultrafast comparator; TCM 1, 2, temperature control module of the SPAD chip and of the CO chip, respectively.

Fig. 2. Simplified scheme of the TCSPC chain. BS, beam splitter; PD, photodiode; Rb clock, rubidium reference clock; TCM 3, temperature control module for the detector.

Fig. 3. (a) Experimental setup. TR, temperature recorder; ET, event timer. (b) Si-SPAD chip. (c) SPAD chip with three-stage thermoelectric cooler in TO-8 housing. (d) SPAD detector module.

Fig. 4. (a) Detection delay of the detector at 18°C and 45°C, respectively. (b) Linear dependence of the detection delay of the SPAD module on its temperature. (c) Propagation delay of the CO chip at 18°C and 45°C, respectively. (d) Relative propagation delay as a function of the CO’s temperature.

Fig. 5. (a) Real-time temperature monitored by Sensors 1–3 during the test of about 120 min. (b) Stabilized real-time relative detection delay.

Fig. 6. (a) Relative detection delay dependent on the ambient temperature. Solid line is the linear fit of the experiment data. (b) The TDEV before and after optimization within a temperature variation of 24°C to 44°C.