I just recently read a little bit into the different technology of lasers for manufacturing and after that I was wondering, why HeNe-Lasers are only able to create less then 100mW of output power, while for example CO2 lasers are available in the kW range.

Unfortunatly I found no direct explanation for that. I could imagine that it is due to the low pressur inside of the tube of the laser and thus the little amount of atoms? But what would keep me from increasing the lenght of the tube to increase output power?

  • $\begingroup$ Just a guess: Cooling? High powered CO2 lasers use a continuous flow of gas through the laser cavity. He and Ne probably are too expensive for that. P.S., I have seen what supposedly was a 300mW HeNe laser for sale in a surplus shop. It was about eight feet long. Never saw it in operation though. $\endgroup$ Feb 28, 2018 at 15:15
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    $\begingroup$ The main issue with HeNe lasers is getting the Ne to relax back to the ground state after emission, which is required to pump it back up again. Collisions with the He and tube walls are the main processes. So, perhaps you could keep scaling up the length, but the 4 orders of magnitude to go from 100mW to 1kW seems kind of difficult unless you have, say, the SLAC tunnel to use. $\endgroup$
    – Jon Custer
    Feb 28, 2018 at 16:58
  • $\begingroup$ Well, yeah that makes sense. So the output power is not limited in general, but by the maximal lenght of your device. And increasing the pumping power would have no effect, because already all atoms are excited and we have to wait for them to relax, right? $\endgroup$
    – jusaca
    Mar 2, 2018 at 7:37


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