pelletier cooling = more power or longer life?

[k-shell]

On my bench i have a nice little pelletier and heatsink. i was wondering how the 803t's would respond to running at lower than 0*c? could i get a few more mA out of them, or would this just give a longer life?

 

[daguin]

On my bench  i have a nice little pelletier and heatsink. i was wondering how the 803t's would respond to running at lower than 0*c? could i get a few more mA out of them, or would this just give a longer life?

Both.  With active cooling you can turn the current up more AND the lower you keep the heat, the less damage done to the crystal.

Although I'm not sure what 0*c alone would do to the diode.


Peace,
dave

[highlight]**EDIT**[/highlight] I think brtaman did some work with extremely low temperatures.

 

[k-shell]

[quote author=k-shell link=1221415249/0#0 date=1221415249]On my bench  i have a nice little pelletier and heatsink. i was wondering how the 803t's would respond to running at lower than 0*c? could i get a few more mA out of them, or would this just give a longer life?

Both.  With active cooling you can turn the current up more AND the lower you keep the heat, the less damage done to the crystal.

[highlight]Although I'm not sure what 0*c alone would do to the diode.[/highlight]


Peace,
dave[/quote]

You think going lower would help? I can stack two Pelletiers together and achieve lower than -20c (with no load). But at that point I’m not sure how to defend against condensation!

 

[Murudai]

TEC things are so cool. I would love to have a nice big one, so I can just switch it on and all of a sudden freezing temperatures

How much would one of that size cost? Along with a heatsink for the heat side and electronics to drive it?

 

[Hemlock_Mike]

There are limits with TEC. Those little wires connected to the laser die will only take so much current before they blow. Also, the optic cavity will take only so many photons before COD trashes the LD. And remember that the LD housing can only conduct a limited amount of power (heat) to the TEC.
The TEC cooler will help but is not salvation for the LD. Long ago, there were many posts from several members about TEC cooling and the benefits. You might want to do a search going back a year on TEC experiments.

Mike

 

[Kenom]

I recall reading somewhere that taking the temperature too low was actually detrimental to the laser diode. You may want to look really close.

 

[FrothyChimp]

The spec sheets indicate the optimal operating temperature range. That range is what you should target. Operating at too low or too high a temperature stresses not only the junction but also the physical components as you will always have temperature differentials within the diode. You may get lensing issues, wild wavelength shifts or even a failure to start. Tie your TEC into a feedback loop with the photodiode and that laser diode will run so stable you won't know what to do with it. Regardless of temperature you still need to keep your current input reasonable.

 

[Kenom]

Ha! see I knew someone more knowlegable than I would speak up and validate my memory.

 

[suiraM]

If its an open diode (chip, open, C-mount, etc.), you could use one of those peltiérs that are intended to be affixed directly to the LD chip itself. Nextreme and Supercool both supply peltiérs that are intended to cool the chip directly in this manner. As FrothyChimp said, the temp should be stabilized and within the recommended range, but with a direct chip connection, you can probably maintain a given temp with more dissipation in the chip. COD is a different matter, of course.

Either way, it's moving out of the hobbyist range of feasibility.