Fig. 1. Schematic of a TO-66 packaged InGaAsP/InP single-photon avalanche diode (SPAD): (a) Cross-sectional schematic of the InGaAsP/InP APD structure; (b)APD chip; (c) Physical appearance

Fig. 2. Schematic diagram of gated-mode single-photon detection system

Fig. 3. Dark current before and after irradiation: (a) Device 1#; (b) Device 2#

Fig. 4. Results of the dark current by in-situ test（Device 3#）

Fig. 5. Dark current before and after irradiation: (a) Device 4; (b) Device 5

Fig. 6. Change of the dark current increment before and after irradiation for Device 5#

Fig. 7. PDEs of APDs before and after irradiation: (a) Device 1#; (b) Device 2#; (c) Device 4#; (d) Device 5#

Fig. 8. PDEs of APPs before and after irradiation: (a) Device 1#; (b) Device 2#; (c) Device 4#; (d) Device 5#

Fig. 9. DCRs of APPs before and after irradiation: (a) Device 1#; (b) Device 2#; (c) Device 4#; (d) Device 5#