We used an SRS Spectrum Analyzer in parallel with an oscilloscope to measure various sources of noise in the 495 mW NPRO laser. We sent the beam into a PDA10CS photodetector and fed that signal to the spec analyzer and the scope. We measured the dark noise, and then the total noise at 2 mW, 4 mW, 7mW, and 9mW. We then did a theoretical calculation for the shot noise, as follows:
N = (Po*dt) / (h*f)
dN = sqrt(Po*dt / h*f)
dE = sqrt(h*f*Po*dt)
dI = dE*(Responsivity of PD)
dV = dI*(Gain of PD)
We plotted all three of these noise sources in matlab. The plot and the code are attached. The directories are:
/users/mstephens/NPRONoise.m
/users/mstephens/495mW_NPRO_Noise.pdf
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