Fig. 1. Diagram of Si APD performance testing

Fig. 2. Si APD current as a function of bias voltage

Fig. 3. Si APD multiplication factor with voltage

Fig. 4. Two-stage amplifier circuit

Fig. 5. Schematic diagram of an adjustable high voltage power supply

Fig. 6. Testing system for detector

Fig. 7. Change of bias voltage gain under direct current light

Fig. 8. Comparison of output sensitivity between Si PIN photodetector and APD two-stage gain adjustable photodetector under pulsed light