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Thermal sensitivity of red diodes?

grenadier

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Hi forum;

I recently got my hands on quite a large red laser diode. I am not sure how powerful it is, /several watts at the very least/, but, the threshold current is 4.5A, and my power supply can only do 5 :)

>>Photo of diode<<

Nonetheless, I have noticed a very strange characteristic with this laser diode. Its output power reduces, substantially, if it is even a tad bit warmer than ambient.

I have not noticed this, with 445 (InGanAs) chemistries. Does anyone know why a red diode would behave this way?
 
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Richie89

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I honestly don't know but holy hell thats a mean looking red!
 

paul1598419

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It's most likely a 808nm diode which is sometimes called red, but belongs to the near IR family of diodes. These are used to pump solid state systems to get a 1064nm output which is then frequecy doubled to get 532nm green laser light. It can also be used to pump other wavelengths.
 

grenadier

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My spectrometer says 650nm :)

If it were 808, I'd be quite afraid. The whole room illuminates bright red when this is on.
 

paul1598419

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What case is it in? It is very unusual for a 650nm diode to be so very thermally sensitive. What spectrometer do you have? Mine is an Ocean Optics USB2000.
 

Benm

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Certainly interesting, i suppose your supply is limiting current at 5 amps?

Perhaps the problem is that forward voltage on diodes drops as they heat up, and there might be some parasitic current in there as well that increases with temperature.

Where did you get this diode from, and do you have any clue on it's typical/maximum forward current? Looks like it needs to be in a big heatsink to operate at full power if you want to test that in any case ;)
 




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