[Laser] APD diodes in Geiger mode

[F1AVYopto at aol.com]

Charles 
I  use today a CA30817 APD silicon diode in Geiger mode for my laser  
experiments. 
Most  of silicon APD can works in Geiger mode if they are cooled at less than 
-40° but  some of them give very poor results. 
I  use a simple adjustable HT PSU to reach the Geiger point and a very simple 
 passive RC quenching circuit. 
I  get about 2500 dark count pulses / second at - 20° with my best 
adjustments but  this functional point is very unstable and change all the  time.  
For  your application you need a very stable HT PSU with a sophisticated 
temperature  feed back loop, an active electronic quenching circuit, a TE cooled 
regulated  package... 
The  best is to buy an all made photon counting module from Hamamatsu  or 
Perkin Helmer but these modules are very expensive.... 
With these  modules you can reach less than 100 dark count pulses in a 
second, a very high  data rate and a great stability. 
73  Yves.