1. Semiconductor Optical Single-Photon Diode
Jie Zhang
Department of Electrical and Computer Engineering

2. Outline Introduction Avalanche Effect APD vs. SPAD Qenching Circuit
Conclusion

3. PMT vs. APD Photomutiplier Tube High amplification Slow Fragile Bulky
EM field susceptible
Relatively expensive
Avalanche photodiode
Similar amplification
Fast
Rugged
Small
Not susceptible
Cheap

4. Structure

5. Avalanche Effect

6. APD – SPAD comparison APD SPAD
BIAS :
MODE :
GAIN :
Below BD
linear
e-/ph
Above BD
Geiger
infinite
AMPLIFIER
TRIGGER
How to observe faint and fast photon sources with the highest QE?

7. Qenching circuit VA hν R1
Vout(t) R2

8. Active Qenching circuit

9. Compact modules
in the 90’s
Integrated AQC
today
Earlier modules
in the 80’s

10. Conclusion
APDs operated at geiger mode together with a quenching circuit can be used as single photon detectors particular in the red and near IR spectral range.
This photon counting techniques provide the ultimate sensitivity and accuracy in measurements of weak and/or fast optical signals.

11. The end……
Thank you!