Photocurrent shot noise correlation function

  • Thread starter Niles
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  • #1
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Hi

I have stumpled upon the following expression for the correlation function of the photocurrent shot noise for a photodiode
[tex]
<\delta i(t)\delta i(t+\tau)> = \frac{e^2\eta}{h\nu}P\delta(\tau)
[/tex]
where η is the quantum efficiency and P the power in the signal. δ(τ) denotes the Dirac delta, which makes good sense as shot noise is white noise. However I am unsure of how the prefactor is derived. Can anyone point me in the right direction?

Best,
Niles.
 

Answers and Replies

  • #2
732
3
Hi

I have stumpled upon the following expression for the correlation function of the photocurrent shot noise for a photodiode
[tex]
<\delta i(t)\delta i(t+\tau)> = \frac{e^2\eta}{h\nu}P\delta(\tau)
[/tex]
where η is the quantum efficiency and P the power in the signal. δ(τ) denotes the Dirac delta, which makes good sense as shot noise is white noise. However I am unsure of how the prefactor is derived. Can anyone point me in the right direction?

Best,
Niles.
I can point in a direction. Sorry that I don't have a text editor, but I think you will see what I am getting at.
{h\nu} is the energy per photon. "P" is the power of the light illuminating the photodiode, which means energy per second. So {h\nu}P is the number of photons per second illuminating the photodiode.
 
Last edited:
  • #3
marcusl
Science Advisor
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No, P/(hv) is the photon flux, which equals the number of electrons/sec. The current is therefore eP/(hv). So I think the question from Niles is: why doesn't the expression above have units of {eP/hv}^2?
 
  • #4
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No, P/(hv) is the photon flux, which equals the number of electrons/sec. The current is therefore eP/(hv). So I think the question from Niles is: why doesn't the expression above have units of {eP/hv}^2?
Hi

Thanks, that is exactly my question.
 

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