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Changing the Color of Lasers/LEDs with Liquid Nitrogen!

styropyro

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Here my labmates and I screw around with some liquid nitrogen and freeze some LEDs and lasers. :D

https://www.youtube.com/watch?v=5PquJdIK_z8



This experiment works by utilizing liquid nitrogen to cool the semiconductor to -196ºC, robbing it of much of its thermal energy. This causes the "bandgap" energy to increase, thereby increasing the emitted photon energy and decreasing the emission wavelength. Very cool experiment!!
 

Hap

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Awesome! Really liked how you managed to get a 635nm diode to end up being 610nm :)


-Alex
 

10fenny

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NERD! ha jk
why did I even my my 589 spartan eh?
This is a badass experiment. was the 635 the only laser you tried out?
 

styropyro

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We also tried a 650nm laser diode, but the change was hard to capture on camera. The green and blue laser diodes do not shift much with temperature like the red lasers, so I didn't bother with those.

In the future, I may get a chance to try this with even colder liquid helium! (T=4K... !!!!!!)
 

Gabe

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You have access to liquid helium at your lab?! I'm even more jelly than I was before
 

vk2fro

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Shame the 520 and 462 nm diode don't colour shift as well as the 635. They would have been neat to see. I assumed (before the video) that the 462/455 would shift up into the uv area, and the 520 would blue shift. That was very cool. Plonk in LN2 for a minute, red laser becomes yellow :)
 

styropyro

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Yeah I wish the blue/green diodes would shift more with temperature!

You have access to liquid helium at your lab?! I'm even more jelly than I was before
Yup, we gotta keep our magnets superconducting! :p Unfortunately I haven't gotten to play with any yet, but when the day comes there will be a video. :D
 

Hap

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Knowing this, could one technically make IR diodes visible?

-Alex
 

Teej

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We also tried a 650nm laser diode, but the change was hard to capture on camera. The green and blue laser diodes do not shift much with temperature like the red lasers, so I didn't bother with those.

In the future, I may get a chance to try this with even colder liquid helium! (T=4K... !!!!!!)
Nice!

Now lets think about WHY the blue green didn't shift as much.

:D
 

weeba2kv

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Styro * Good media going on there man ! keep up the great vids on your channel , btw how's that yellow DIY laser going on |mA0 it's been like 2 years now /o/
 
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Gabe

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Nice vid! No laser goggles though? :p
Well if he was pointing it at his lab partner, and the module doesn't have a heat sink, it can't be more than 5mW. Styro would have more sense than that :p

EDIT:Whoops! Didn't see the :p at the end of your sentence, didn't know you were kidding around.
 
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styropyro

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Nice vid! No laser goggles though? :p
The laser diode was running just above threshold, so its output was low! I did this not only for safety reasons, but also to keep the wavelength low.

Knowing this, could one technically make IR diodes visible?

-Alex
This would be a stretch, because the IR visibility curve doesn't really have a dramatic drop off. Maybe a 830nm laser diode cooled to 800nm would do it, but it would still be very dim! Plus, everybody sees the NIR wavelengths different so some would start off seeing the 830nm.
 




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