Liquid Nitrogen Cooled Oclaro 638nm Laser Diode??

In the lab I work in I have access to oodles of liquid nitrogen...we use it to help keep the liquid helium in our NMR magnets cool. So of course, the idea of cooling the piss out of laser diodes to induce a massive blue shift came up and now I want to try it.

So I took a look at the datasheets for some of our more common hobby laser diodes to see what kind of wavelength shift I can expect. Unfortunately, the green and blue laser diodes don't shift that much with temperature. What did catch my attention is that the 635nm laser diodes do have quite a wavelength/temperature slope...about 0.2nm/K near room temperature. Assuming this trend is linear, a 635nm laser diode cooled to liquid nitrogen temperatures could be blue shifted to ~595nm.

So that makes me wonder...has anybody here played around with liquid nitrogen cooled laser diodes and had any success? If so, any tips? I can see condensation being a major issue...so I am thinking about building a thermally conductive cell to contain the laser diode, and throw some desiccant in there to suck up as much water as possible before cooling.

Any input would be greatly appreciated! If I have any success with the experiment I'll be sure to post spectral/power data and a video. :beer:

If it helps, this was a 660 in N2


and heres what they measured:

"Wavelength:
659nm @ 25°C
628nm @ -196°C
shift: ~0.14nm/°C"

and this an orange LED


The shift in the wavelength for the LED is very interesting.

I think Ive seen 638 or 635 diodes discussed so Ill see if I can dig something up.:beer:

Edit: IIRC Boomie was also discussing it a while back and was thinking of designing an hermetically sealed host with silica as dessicant.

Edit 2: Heres an LPF thread with some interesting videos on the topic:
http://laserpointerforums.com/f54/anyone-tried-laser-diode-huge-wavelength-shift-88534.html

Third video from Boomies post :

Well, there is a video on youtube where a 638 nm laser gets cooled down enough to emmit 605 nm which is orange, i just dont have the link. Someone posted it in a thread here on LPF but i couldnt find it.

Moisture isn't really a problem. I have
flooded one of my C-mount diodes with
isopropanol before and it still works. It
didn't seem to have any detrimental effects
on output power. It probably isn't a good
idea to power it while it's wet, but ultra
pure water (condensation) is a good
electrical insulator. Water is even used
during the manufacturing process.

Now ice building up on the die face or
window could be a problem, as it will
scatter light and possibly reflect some
back into the resonator. If anything
though it will only decrease the power
required to induce optical damage. It
shouldn't be a problem if the diode is run
below spec.

The bigger problem will be thermal shock.
If the crystal and the case expand and
contract at different rates, the die may
become dislodged. The temperature should
change about 6° or less per second. At
least that is what JDEC recommends for
reflow soldering. That is a little
different, I know, but it is good practice,
anyway.

Closed can diodes will have the added issue
of the window. If the diode heats up too
quickly, the pressure buildup could burst
the window.

If all you are doing is measuring
wavelength shift, just cool the heatsink
slowly with increasing amounts of LN2 and
then flood the thing. That will cover any
ice that may have formed. Make sure
everything stays submerged during the
remainder of the test.

For warmup with open can/die diodes,
nothing special needs to be done other than
controlling the speed of the warming
process. For a closed can diode, either
decan them or allow the liquified gasses to
evaporate slowly out of the can (they are
usually not a perfect hermetic seal) and
then proceed the same as with the others.

Here it is, i found it.

http://www.youtube.com/watch?v=0w4czym1FFg

If you wanna see the color, go to 30 mins, there you have your beautiful 608 nm orange.

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.

Hey Styro did you manage to make any progress yet on this experiment? Wondering if a shift from a 635 down to the ~ 590 range would be plausible?

Not yet! I will be visiting my family over the next week so I'll be away from the lab, but that should give me some time to create a cooling cell of some sort for the laser diode. Assuming that works, I'll get the cooling experiment done near the end of next week. I am excited!

Will watch with interest, subbed

I found this - (The Cryogenic Laser)
https://www.youtube.com/watch?v=0w4czym1FFg

Near the end of the video the diode was lasing at ~605nm, close to 1/2 watt. It appeared almost yellow. Through a grating it was a sunrise/sunset color.

Unfortunately doing this requires an expensive apparatus and liquid nitrogen

Thanks for the find, very interesting video, I wonder if the guy has ever been a member on these forums?

Very nice, indeed! I have some of these diodes and am thinking of trying this too. I was unaware that one could get such a dramatic sift in the wavelength.

SteveT said:

Thanks for the find, very interesting video, I wonder if the guy has ever been a member on these forums?

Click to expand...

Yes, he is planters on both LPF and PL, although he is mostly on PL.

Just did a trial run...it was AWESOME!! I'll see if I can get pics up before long.

Here's a pic...I do have some videos too that I may post!

Wow, thats awesome, cant wait to see the video.

Aww, to bad i can't rep you atm