Summary: Measurement and plot of shot-noise-intercept-current for PDA10CF.
Motivation:It is to measure the shot noise intercept current for PDA10CF.
Result: The final plot is attached here. The plot suggests that the value of shot-noise-intercept current is 0.21mA
The plot is for the measured data of Noise voltage (V/sqrt(Hz)) vs DCcurrent(A). The fitted plot to this measured data follows the noise equation
Vnoise = gdet* sqrt[ 2e (iDC+idet)] , where gdet= transimpedance of the PD in RF region as described in manual of PDA255 (i.e. 5e3 when it is not in High-impedance region).
To get an approximate idea of the shot noise intercept current, we may follow the same procedure described in 7946
In the present case dark-noise is 4.3e-08 V/sqrt(Hz)
Therefore dark current(in2) ~dark noise voltage/RF transimpedance = 8.6pA/sqrt(Hz)
Therefore the approximate shot noise intercept current ~ (8.6/18)^2=0.22mA
This value matches well with the fitted data.
From PDA10CF manual, NEP=1.2e-11W/sqrt(Hz) and responsivity~0.9A/W. Therefore the noise current level will be ~10pA.