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Message ID: 2745     Entry time: Wed Mar 31 19:29:58 2010
Author: Hartmut 
Type: Update 
Category: Electronics 
Subject: (1cm-) Si PD transfer functions update 

Recorded transfer functions for the 1cm Si-PD as described on p. 2708

for different biases. I put the plots in there, to keep the info in one place,

where the label on the PD case (which Steve made without asking him) points

to.

I talked to some people recently about the fact that the responsivity (A/W) of the PD

changes even at DC for different biases. I tested this again and should be more precise about this:

The first time I observed this was in the transfer functions as shown on p. 2708.

With 'DC' I meant 'low frequency' there, as you can still see an effect of the bias as low as 100kHz.

Then at one point I saw the responsivity changing with bias also at true DC.

However, it turned out that this is only the case if the photocurrent is too high.

If the photocurrent is 4mA, you need 400mV bias to get the max. responsivity.

For 2mA photocurrent, the responsivity is already maximal for 0V bias.

An effect for relative low frequencies remains however.

The DC check of responsivity was done with white light from a bulb.

 

 

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