# Output voltage of a photodiode

1. Jun 23, 2013

### phoneketchup

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!

2. Jun 23, 2013

### Carl Pugh

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

3. Jun 23, 2013

### phoneketchup

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

4. Jun 23, 2013

### phoneketchup

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?

5. Jun 24, 2013

### phoneketchup

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

6. Jun 24, 2013

### davenn

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

7. Jun 24, 2013

### Carl Pugh

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

Good Luck
Carl

8. Jun 27, 2013

### phoneketchup

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.