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Liquid Nitrogen Cooled Oclaro 638nm Laser Diode??

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Wow, I did NOT expect the diode to drop that quickly- I guess I was comparing it to Planters vid where he slowly lowered the temp, though. That'e awesome, thanks for sharing!

I'm sure you could get some sort of air tight "capsule" machined to transfer this to a handheld, but I'm not sure I would want to be waving a canister of liquid nitrogen around. May be better suited for a [stationary] labby type setup ;)
 
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Just watched that vid. That is amazing how much these can shift by cryogenic cooling them. I sure didn't expect it to go past orange and start going towards yellow at all.
 
It looks like it might of went under 600nm.

as that one pic looked closer to a 589nm laser
 
Just got some spectro readings done!! Before cooling, the laser was running at 635.6nm, and after freezing it ran at 610.6nm. I would have thought it dropper further based on the color, but I guess not! I also got some more good footage...I might be able to post a public video now. :p
 
styropyro said:
Just got some spectro readings done!! Before cooling, the laser was running at 635.6nm, and after freezing it ran at 610.6nm. I would have thought it dropper further based on the color, but I guess not! I also got some more good footage...I might be able to post a public video now. :p
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Thanks for the update Styro and looking forward to the vid; I too thought it was closer to ~600nm. Since your experiment I've placed an order for a 589 Spartan...something magical about that yellow!
 
Awesome let me know how that turns out!! I'll probably bite the bullet and order one of those eventually...
 

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I too expected a bigger shift based off how it looked, but then again look at how different 520 and 532 look with only a 12nm shift. It doesn't take much to make a pronounced difference!
 
Would this also work with other colors? Like, a 520nm diode cooled to 500nm, or a 405nm diode cooled to the UV :wtf:? That would be really cool to see. Keep it up styro!
 
So I recently got the chance to play with some liquid helium (4 degrees C above absolute zero :D ). I dropped this diode in the helium, and it went from 635nm to 605nm before popping. The forward voltage jumped from around 2V to near 8V!!! I'll try to get around to posting a video.
 
(Understanding that I don't know how cold Dry Ice could get the diode) Would it be possible to make a metal host and have a smaller sealed "block" that could cool the host only through contact. So basically drop in a couple cubes of dry ice and wait for it to cool the host. Would it be capable of blue shifting enough to notice? Would the can need to be opened? In no way would the dry ice come into direct contact with the diode, just the "heat sink". :thinking:
 
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styropyro said:
So I recently got the chance to play with some liquid helium (4 degrees C above absolute zero :D ). I dropped this diode in the helium, and it went from 635nm to 605nm before popping. The forward voltage jumped from around 2V to near 8V!!! I'll try to get around to posting a video.
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The forward voltage going up is not a good thing here. I reckon there is some reason the laser diode doesn't function properly at such a low temperature causing the problem/failure.

At dry-ice temperatures semiconductors typically behalve similar to room temperature, apart from lower losses and in case of laser diodes a significant shift in wavelength. Once you go to liquid nitrogen problems start to arise, and at liquid helium i reckon they don't really "work" that well any longer.

It would be a bit like trying to overclock a processor: that usually works fine with CO2 and liquid nitrogen, but with helium cooling it might get so cold that it actually doesn't function any longer. Obviously semiconductors can be built to operate at very low temperature, but regular stuff built for room temperature doesnt always work reliably under extremely low temperatures.
 
Trendkilla254 said:
(Understanding that I don't know how cold Dry Ice could get the diode) Would it be possible to make a metal host and have a smaller sealed "block" that could cool the host only through contact. So basically drop in a couple cubes of dry ice and wait for it to cool the host. Would it be capable of blue shifting enough to notice? Would the can need to be opened? In no way would the dry ice come into direct contact with the diode, just the "heat sink". :thinking:
Click to expand...

Reminds me of an idea I had a while ago.

Anybody know what would happen if you stuck a stirling refrigerator to a diode?
 
I'm not sure, but wether you can notice the color shift: It often is about 0.2 nm/K - at least at reasonable temperatures.

This would mean that a 405 nm diode would shift to about 409 at 70 celcius vs ambient. On the red end cooling a 638 nm down with dry ice would result in a shift to perhaps 625 nm (depends on the actual die temperature, not just the case!).

Both changes could be visible if you compare the color to a unit running at normal temperature. Color difference is probably less specatcular than brightness improvement when going from 638 to 625-ish.

I'm not sure how far down that 0.2nm/K keeps up though, i doubt it holds true at dry ice, and i'm quite sure it doesnt remain at that value at LN2 temperatures.
 
styropyro said:
Oh wow, LOTS of good input here, thank you! Thermal shock is another good point, I will make sure to try my best to smooth out the cooling of the laser diode. Maybe I'll do some trial runs with cheaper laser diodes before I throw a nice mid power SM 638nm laser diode in there.

All the videos in here are awesome too! The LED was pretty cool too, I'll have to give that one a try. Plus, that 608nm beam is awesome!! This gives me more fuel to get going on this project. :D
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I wonder how this affects the current requirement. That is why liquid helium is used in clinical MR. You have virtually no resistance as you know. So, is the diode simply capable of handling more current and this produces the shift or is the shift directly related to temperature?
 
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