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Strange behavior of the red laser

Snecho

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Oct 2, 2019
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Thanks for your honesty. No hard feelings...

I don't know if that particular diode with the burnt spot was from back reflection but i strongly suspect it was. I do specifically remember decanning a 9mm 660nm that had back reflection cod and seeing the same type of damage/burn though. In my experience with the 650nm-660nm diodes if you over drive it to the point of failure it will either blow/lift the top gold layer on the semiconductor or vaporize a section of the bonding wire/s, thus causing an open circuit. I have also seen facets burnt do to overdriving but just not as often. Unfortunately I've killed more diodes than I'd like to mention... Usually if your overdriving a diode and it just stops working (doesn't go led), you have a chance (my record is about 50/50) at saving it if just a bonding wire blew. It's a pita of a soldering job to bridge the connection but if you have a REALLY steady hand it can be done. Just keep in mind that a soldering iron tip is gonna look like the size of a baseball bat next to that bonding wire under magnification and a slight flinch and it's all gone.
What did you mean by the term "led the diode"?
 



Ramsey_innovations

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May 10, 2009
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What did you mean by the term "led the diode"?
It can happen when a laser diode is overdriven or back reflected causing a point of failure where it will no longer emit light at its previous potential output. It will only glow faintly, indicating that it had suffered from overheating of the semiconductor resulting in melting and recrystallization of the facet and/or damage to the p-n junction.
 

Snecho

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Oct 2, 2019
Messages
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It can happen when a laser diode is overdriven or back reflected causing a point of failure where it will no longer emit light at its previous potential output. It will only glow faintly, indicating that it had suffered from overheating of the semiconductor resulting in melting and recrystallization of the facet and/or damage to the p-n junction.
Ah ok, so basically catastrophic damage occurs and it physically changes the die, making it only faintly emit light rendering the diode useless.
 




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