Diode lives AND lases at -100F?

Just some considerations (so you can hate me j/k )

First, closed cans can become damaged as the others, cause the extreme low temperatures can detach or shatter the window (more than other the temperature change, but you have also to considerate that the expansion / contraption rate of the can (metal) is usually not the same of the window, and the mechanical stress can cause detach of the glue or damage of the glass.

Same consideration, also if for a different thing, can be made about the chip ..... don't think to the soldering material, that have a rate similar to the glass, but about the metallic part where the chip is soldered on ? ..... usually, in the constructive process, is kept in consideration the increase of the temperature, not so much the decreasing of it ..... ok, the wavelenght can change a bit, cause also when the chip contract, the distance between the resonant faces (coating) decrease, but if the decreasing rate of the metal support is too much different of the one of the chip material, there's always the risk of breaking (chips and creeks) ..... especially pumping in the chip a big amount of energy, when it's at very low temperatures, making it expanding more quick than the support (but, maybe, IF it can work fully immersed in the cooling liquid .....)

Also about this ..... as you probably know, reflection characteristics of surfaces changes when you change the medium in which they are immersed (think to glass in air and water differences) ...... in full immersion in a liquid, the dielectric coating that make the resonant cavity, can, maybe, change its reflective properties enough to make the chip just not lasing, or changing it basically ?

Just an idea

Lots of unknowns here - the window on a closed can could shatter, filling the diode with solvent and causing problems there. Its an experiment, not something i'd consider using any expensive diode for. You could just use the basic 5 mW in an aixiz, just to see what happens.

The reduction in wavelength is not caused by contraction of the cavity at all, its caused by lower bandgap at lower temperatures for the semiconductor used. Normal diodes exhibit the same effect, their forward voltage (at equal current) drops with increasing temperature (by about 2 mV/K for standard silicon diodes).

The diode I used in the original test was the low powered red laser from the phr sled. The window did not crack and after 10-15min nothing significant happened. The diode was uncollaminated and i could not see any visible change in wavelength. It was just one diode though and I haven't tried any higher powered diodes yet. I'll get a lcc diode and try it again. -hydro15

Although it is unlikely the diode could ignite the alcohol and become a fire hazard.

millirad said:

Although it is unlikely the diode could ignite the alcohol and become a fire hazard.

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I have a fire extinguisher 5 feet from where the experiment takes place in the event that something goes wrong. Theres also the possibility that the CO2 will simply extinguish the fire by displacing the oxygen.

--Hydro15

Once its cooled down, the alcohol (ethanol or isopropanol) will be below its flashpoint, and hardly any vapours. You would not be able to ignite it with a lighter if you wanted to.

Obviously this only goes for the CO2 cooled alcohol, and spills evaporating from the table will still pose a risk.

I think most canned diodes should survive being frozen like this. The temperature change is in the order of 100 kelvin, which is comparable in temp change to what happens to the diode when you solder it carelessly.

I'd try it right here if i could get some dry ice... but since i dont work in the lab anymore, its not easy to come by here - unless i want 25 kg of the stuff deliverd. As I understand it is sold in the US in some major supermarkets and welding supply stores etc.

^Yep, many supermarkets sell dry ice here in the US. I can get good sized blocks right down the street at Ralph's.

Although it was always nicer working in a lab when we were using dry ice a lot, because the form we got it in was narrow rods that were 1-2 inches long and exactly the right width to go into the opening of a Coke bottle. Very convenient, a lot of fun, and we never went through all of it in the lab (we could only get it in 50lb quantities), so we had plenty to play with after work every day.

pullbangdead said:

^Yep, many supermarkets sell dry ice here in the US.

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Hell, now i have a new thing to be envious ..... here, only as lab or industry, or show market, you can buy dry ice ..... and for sure, not in a supermarket, only in specialized resellers, and ofcourse, at high price