liquid nitrogen cooled laser power?

[neskusen]

I've seen few people on youtube use liquid nitrogen to cool a red laser until its wavelength shifts to orange.
That's pretty cool, although impractical.
What might also be cool but impractical is cooling a laser diode in liquid nitrogen and overdriving it. To people who actually know how the technology works: how much do you think someone can add to the recommended current in such temperatures and still not fry the diode? Or is it too little to bother testing even just for fun?

[mixedgas]

Supercooling the diode lowers its damage threshold at some point as you cool. The diode becomes more and more efficient to the point the intracavity power builds up to cause a COD (Catastrophic Optical Damage) failure. So as you chill diodes very cold, you have to actually back off on the pump current. The gain in efficiency is thus offset by the need to reduce power. In Thermodynamics, there is no free lunch, according to the 2nd Law...
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Most diodes are specified at currents that are very close to their damage threshold, divided by one point two five or so. Call it a sensible engineering reserve selected by the manufacturer. A common thing from diode using hobbyists is to push the diode harder then spec, to begin with, thus eating away at overall lifetime and getting closer to COD. All in the name of "More Power!"
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The gain in power for chilling the diode that far is miniscule compared to the time value of money for making and obtaining the LN2 and the additional hardware needed to do this.
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Sadly, most things that are "Physics according to Hollywood" are pretty bad distortions of the truth.
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Cooling diodes helps, but there is a limit to how well it helps.

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Steve

[neskusen]

Thanks for clearing that up

[VDX]

... I was surprised to see, that some IR-diodes with max 9Watts@975nm at 9Amps of power while testing with a new developed driver could melt a clean plastic lens, specified for powers >20Watts!!!

Then, while testing this driver with a 445nm-diode I've noticed some serious spikes and oszillation at specific power settings.

Then tested with a shunt resistor only and got spikes of up to 30 Amps with duration times of some ten nanoseconds!

So the 9W-diode emitted a lot of power spikes (some minutes testing) with much more than 20 Watts before dying away ... could be interesting to try this again with serious cooling

Viktor