Fig. 1. (Color online) Structure Diagram of the SPAD.

Fig. 2. (Color online) (a) Edge of double diffusion profile of the optimized device observed by SEM. (b) Simulated optimized device electric field diagram after breakdown (V_ex = 0.5 V).

Fig. 3. (Color online) (a) Dark current versus reverse bias voltage at different temperatures and the photo current versus reverse bias voltage at 298 K. (b) Breakdown voltage versus temperature data (symbols) and linear fitting (line).

Fig. 4. (Color online) Dark current versus multiplication factor and its linear curve fit at 298 K.

Fig. 5. (Color online) Natural logarithm ofI_d /T² versuse/kT at different reverse voltages.

Fig. 6. (Color online) The test system diagram of dual-balanced single-photon detectors.

Fig. 7. (Color online) Dual SPADs balanced detector with fiber-coupled package.

Fig. 8. (Color online) Oscilloscope output under different conditions. (a) The external single period sinusoidal pulse gating signal. (b) Capacitive spike pulse responses of the individual APD1 in the dark with a single sinusoidal signal biased. (c) Output in the absence of incident photons, two SPAD sinusoidal bursts biased. (d) Output when a photon is incident and an avalanche pulse is generated.

Fig. 9. (Color online) The photon detection efficiency versus dark count rate at different temperatures.

Fig. 10. (Color online) The relationship between NEP and excess bias voltage at different temperatures.

Table 1. Comparision of our detector with similar detectors recently described in literature.