Results 1 to 7 of 7

Thread: Side pumping

  1. #1
    Join Date
    Sep 2010
    Location
    Cambridge, MA
    Posts
    95

    Default Side pumping

    What is the most efficient way to side-pump a 1.6 mm 0.5% Nd:YAG rod with diodes?
    Butt-coupled with no optics, a specular reflector, a diffuse reflector, or something else?
    My diodes don't have fast-axis correction
    How do the commercial folk do side-pumping?

  2. #2
    Join Date
    May 2009
    Location
    UCSB
    Posts
    708

    Default

    Generally you clap the rod in a block of copper (either with indium foil or a thin layer of thermally conductive glue) and directly butt couple into it. You want the rod a little ways away from the diode so that you don't melt it and the pump is at least somewhat uniform.

  3. #3
    Join Date
    Sep 2010
    Location
    Cambridge, MA
    Posts
    95

    Default

    I wonder if passive cooling will work for the 300+ W of pump diodes I have now.
    I've been trying to figure out how to clone the Avia's sexy donut+flowtube assembly without an expensive coated flowtube.

  4. #4
    Join Date
    Oct 2010
    Posts
    118

    Default

    No, passive cooling won't be enough.

    Remember, each diode will have a TDP from 1.5-3X it's rated optical output power, so your 300W diode will have a TDP close to 500-600W. Hence, it'd be easier to deal with if they were individual bars, and if you were going to use water cooling instead.

    Bear in mind your average computer CPU has a TDP of 65-95W on average, and it takes a somewhat-large chunk of metal (and a fan) to dissipate this heat. Passive cooling isn't an option (without a massive heatsink and heatpipes to conduct heat away from the contact surface).

    As a result, watercooling is much easier, and is usually always the preferred option with higher-power lasers, be it lamp or diode pumped.

  5. #5
    Join Date
    Sep 2010
    Location
    Cambridge, MA
    Posts
    95

    Default

    The diodes are individual bars.
    I'm more worried about dissipating 200+ W of power in the tiny rod than cooling the diodes, given that the diodes are MCCP water-cooled packages anyway.

  6. #6
    Join Date
    Oct 2010
    Posts
    118

    Default

    Quote Originally Posted by bwang View Post
    The diodes are individual bars.
    I'm more worried about dissipating 200+ W of power in the tiny rod than cooling the diodes, given that the diodes are MCCP water-cooled packages anyway.
    A water jacket around the rod will be fine for cooling, that's how most lamp-pumped and high-powered YAG lasers are cooled.

    Just keep the temperature of the rod even, and although it's not like Nd:YLF which goes "KASPLODEY LOL SHATTERING *pieces*", a temperature difference or a sudden change in temperature will cause thermal-induced stress and possibly damage the YAG rod.

  7. #7
    Join Date
    May 2007
    Location
    Minnesota
    Posts
    160

    Default Side Pumping

    Bwang,

    One of these is an easy way to side pump yag using a 20W 808nm laser diode. Gold plated coupled cavity and only passive cooling is used, no tec...

    http://cgi.ebay.com/Yag-Laser-Rod-2m...item25616757fc

    I have a few 2.5W 532nm CW DPSS units made by Lightwave (jds uniphase) and these are used inside. They are also used in other lasers like this 355nm one that was on ebay recently...

    http://cgi.ebay.com/JDSU-Lightwave-X...item4cf4f5ba9a

    What's interesting is you can use a standard diode bar to pump the cavity, ie. no focus rod is needed. The diode output illuminates a smallish slit on the open side of the nd:yag cavity. Another benefit is that the yag rod doesn't need an individual tec either.

    I can't vouch for this particular seller so beware. This may be a seller that's just taken a new ebay name...

    I've bought 4 of these before from 2 separate ebayers and of these only 1 of 4 was good! Its easy for the yag rod to be cracked inside and it's hard to see. The ends might be there... and look good... but...

    With this auction I tried to make an offer but I think $75 might be the low end the seller will accept!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •