1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Thermal Conductivity and Lasers

  1. Apr 14, 2016 #1
    1. The problem statement, all variables and given/known data
    My textbook on lasers has mentioned thermal conductivity a few times, but hasn't specifically mentioned it's importance. I'm at a part talking about Nd:Glass lasers and it says that glass has a lower thermal conductivity than Nd:YAG lasers, which prohibits continuous wave (CW) operation and limits the pulse repetition frequency in pulsed operation to a few Hz.

    My first idea was that low thermal conductivity would be bad for semiconductor and solid-state lasers because if the heat isn't spread out over the gain medium then it could cause stress/damage of that one part of the gain medium, and that it would be much harder to cool a certain area of the gain medium, whereas with higher thermal conductivity you could have a uniform cooling across the whole gain medium without having to worry about hotspots.

    Am I missing something? I'm imagining thermal conductivity isn't really mentioned in regards to gas or dye lasers because it's so low, compared to that of solid-state and semiconductor lasers.
  2. jcsd
  3. Apr 14, 2016 #2


    User Avatar
    Science Advisor

    Yeah, steep thermal gradients can result in mechanical failure. Physical warpage of the medium is also a possibility. Then there is the change in optical and electrical characteristics with temperature. In gas Lasers there is at least a little convection flow which helps, and some gas Laser designs use continuous flow. A friend had an early design CO2 infrared Laser that used a tank of CO2 and vented it to the atmosphere after one pass thru the Laser cavity. Had to get a full tank now and then, but it was a neat toy. Probably others here can come up with some more 'explanations'.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted