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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Hi all. Just had a thought, if we can use a crystal to double 1064nm to 532 (aka green laser pointer), with the advent of >600mW 395nm diodes can we then double that to 197.5nm?
This would be handy for air breakdown and other interesting experiments, such as DUV lithography at home.
Some sort of nonlinear crystal ought to work, the efficiency would suck though.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
SHG efficiency scales as the square of power density; without some sort of external cavity to enable intracavity doubling it is unlikely to produce any significant power.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
There aren't a lot of crystals transparent that far into UV. Just quartz, sapphire and CaF2 ... I don't think any of them can be used to frequency double lasers.
but, I don't see it doubling a diode laser any time soon. To get any decent conversion rate, you need one of this:
Flash lamp pulsed laser (high peak power), or Q Switched pulsed or QCW laser, that also has high peak power. or a intra cavity doubler, where you have very high circulating power.
With my flash lamp nd:yag I had no problems whatsoever to get 532, just focus on a KTP and you have green. It would be interesting to see what would happen if I focus the green on a third harmonic generator crystal.....witch I don't have...
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
It is possible to frequency double 400nm to 200nm (using crystals such as LBO) however starting with a diode laser is extremely hard. You need very high power densities to get any sort of nonlinear effects (ie, SHG), which diodes cannot produce. It is possible to double 900nm-450nm because there are very efficient nonlinear crystals available at that wavelength, but even still you need very careful temperature tuning and if you want good beam quality/usable output powers you often need to set up an external laser cavity which requires extremely stable setups (the commercial lasers have the entire cavity on a temperature controlled quartz crystal) and a very fast feedback loop to tune the cavity length--not easy for a hobbyist!
Also, I wouldn't get your hopes up for the prices of 395nm diodes dropping in price any time soon, we got lucky with the 405 ones because of the electronics market, but 395 will always be in a niche.
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Frequency doubling 395nm?
