# Output voltage of a photodiode

Hello everyone!

I'm trying to figure out how to calculate the output voltage of a photodiode in the photovoltaic mode.
I want to generate about 5-10V using lasers and a series of photodiodes without using an op-amp (just Vout of the photodiode equvivalent circuit). If I could get any help with this I will be very appreciative.

Cheers!

## Answers and Replies

A start would be to go to digikey.com and search for photovoltaic.
CPC1832N has 10 volt output.
Get datasheet for CPC1832N.

Do you know how I can calculate the output voltage of the photodiode due to a laser of a given wavelength and power?

Or is it something like for any given wavelength/intensity (as long as its bright enough and above the threshold wavelength) the output voltage will be very close to the open circuit voltage?

Yeah I was talking about photodiodes but solar cells would work just as well. Basically what I need to do is use a laser(s) to illuminate photodiodes/solar cells and get a constant output voltage of about 5-10V which is the voltage input for an HV module that will give me an output of 2kV which will power a PMT. Everything apart from the laser will be at cryogenic temperatures. So i'm basically trying to power a PMT optically. The website you sent me really helped -- just to confirm do I just go by the open circuit voltage of the photodiode/solar cell? How do I know what voltage output I will get for a given intensity and wavelength of a laser? Will it be close to Voc at a high enough power as it increases logarithmically with the energy of the light? Cheers

davenn
Science Advisor
Gold Member
I don't know how a solar cell would respond to a single wavelength of light
I could only assume it would not be able to generate its full potential as it would when exposed to the full spectrum of sunlight
It would at least be a good experiment for you to try and report back :)

Dave

Try Googling "power over fiber optic", you may be able to purchase something that has already been designed.

Good Luck
Carl

Carl, I'm really liking the solar cell you suggested and I may even get it for fun since its so cheap. I sent an e-mail to the company twice to get the spectral response---no reply. Anyway cheers for that! Also for telling me about digikey.

You're right Dave I don't think any photodiode would respond to a single wavelength. I guess I'll try to find a laser of wavelength closest to the wavelength for which I will get the highest response. Haha yes it's a fun experiment. But before I go ahead and do that I'm gonna have to check how they perform at 77K-- so some liquid nitrogen fun! :P

Thanks for the help! I shall update you'll on how it all turns out.

P.S I googled power over fiber optic earlier but didn't find much. Although I don't think I looked hard enough so I'll probably give it another go.