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FrozenGate by Avery

CNI and their 604/607nm DPSS...

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I currently have 2 Pr:YLF crystals at hand. Going to try them in the following months. We'll see if I can get any orange/red out of them :-)

But their fluorescence is much weaker than I expected - I can see the Pr lines but that's about it, probably my pump laser had slightly wrong wavelength... It barely shines red... If any of you seen Pr:YLF crystals - how did their fluorescence looked to you? Any suggestions are welcome.
 
BarsMonster said:
I currently have 2 Pr:YLF crystals at hand. Going to try them in the following months. We'll see if I can get any orange/red out of them :-)

But their fluorescence is much weaker than I expected - I can see the Pr lines but that's about it, probably my pump laser had slightly wrong wavelength... It barely shines red... If any of you seen Pr:YLF crystals - how did their fluorescence looked to you? Any suggestions are welcome.
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What WL is your pump diode? Pr:YLF's highest absorption peak is at 443nm, so it would probably be worth it to spectro the diode and try to keep the wavelength as close to 443nm as you can via TEC. Also, for better results you can regulate the crystal temperature as well.

You will of course need the appropriate HR and OC mirrors as well to make it lase.

If you don't mind me asking, where did you acquire said crystals?
 
You can get them by request from a few places, but simply having a random Pr:YLF isn't enough. They need the right cut, as well as the right length, dopant level, coatings, and mirrors you also need many watts of a good quality, phase matched beam. Pr3+ doesn't like to lase, and simply running a 445 through it isn't going to do it. And it lases mostly in the red and IR if I remember correctly. Green, blue, and orange are much harder to get. I've seen it done with something like a 5W argon as well as a 1-2W diode, and both cases they didn't get much out. A diode would work, but it needs to be temperature monitored and very preferably single mode at 443, and a very high laser quality correction lens would be needed bare minimum. We used a 100mm lens in our experiment AR coated and 2 dedicated mirrors specially for it.
 
Excuse me for writing that in a hurry. But yes you're right, but does still help greatly to stablize the input. Depending on the type of cavity you want...You wouldn't need to do it for a linear cavity. (Though it will still help a lot)
 
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BarsMonster said:
Mine are 4mm long, 0.7%. What are the effects of the cut?
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0.7% should work, based on what I've read. It should probably be cut along the a or c axis of the crystal. IIRC the cut effects the IOR of the crystal.
 
That is quite a bit on the smaller side, but should work as long as your beam input is very small and well managed, and the surfaces are AR coated for both wavelengths. Your input will need to be perhaps .1mm though or smaller. Higher the density the more efficiency you're going to get. Just be careful not to mar the crystal. what are your mirror coatings and curvatures and reflectivities, etc? Keep in mind that Pr3+ Is self re-absorbing, much like Ruby so you have to overcome that. It'll have a high threshold compared to a YAG
 
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ultimatekaiser said:
That is quite a bit on the smaller side, but should work as long as your beam input is very small and well managed, and the surfaces are AR coated for both wavelengths. Your input will need to be perhaps .1mm though or smaller. Higher the density the more efficiency you're going to get.
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Smaller side on doping or length? My hope was to not going that tight on input or even do side pumping... Is it already lost? :-)

ultimatekaiser said:
what are your mirror coatings and curvatures and reflectivities, etc? Keep in mind that Pr3+ Is self re-absorbing, much like Ruby so you have to overcome that. It'll have a high threshold compared to a YAG
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For first tests my intention was to go with flat-flat. This way I can start with 99.5% dichroic mirrors I already have. Crystal AR coatings 0.5% for both wavelengths, but I will try to improve this.

I've seen data that cooling Pr:YLF crystal to 10C improves the results. Does it help to cool it further?
 
You need the small diameter to get anything. And you can't really side pump it Without HUGE power input. You need a really high power input, and that's the typical way it's done, even with a yag. It's a bit to short for side pump, but I suppose not impossible. It's not that realistic. Cooling the crystal probably does help, as it probably helps with depopulation. Just don't let the temperature change too rapidly or you'll crack or micro-fracture the crystal.

You'll need to use something like a hemispherical or long radius cavity-something concave. To be frank a plane-plane resonator is pretty much impossible unless the gain is exceptionally high. And even then it's quite nasty and math-y to do and unstable. They're typically used in VERY high power YAG lasers, and even then it's not a true planar resonator, as they're taking advantage of the heat to utilize thermal lensing, making it concave.

The paper that I'm reading here says they used two 50cm curved mirrors, and another says they used a hemispherical config, with the crystal in the center in the focal point in both cases. Optimal OC is about 2-3.5% transmission depending on input.

You will need specialty mirrors for this. Regular helium neon laser mirrors won't work. You'll end up with red instead, as the emission at 640 is far stronger.
 
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Someone did it with a low dopant but longer crystal for better efficiency at one point. It's still a growing study. Where'd you order yours from just out of curiosity? The dimensions of the crystal generally are in relation to the cavity setup. The one we used here was 2x2x6mm DBAR 444/609. I think it was doped higher though around 1% iirc, and was pumped by a 'circularized' 1.1W 445nm laser diode. It was spectro'd lower though since it wasn't driven full power.
 
Feel like I suddenly walked into the foreign language thread lol
 
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