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Pumping nd:yvo4 and KTP with sunlight.

GooeyGus

GooeyGus

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So, I have a bunch of crystal sets here from various green handhelds, from 5mW to 200mW. They already have all the coatings and everything, so I wouldn't need to make a cavity. I was wondering, if I set up some sort of jig to get everything stable and use a lens to focus the light right onto the crystal, should I be able to get one of these crystal sets to lase? I'm not expecting it to make any crazy laser or anything, I just think it will be a cool experiment to show someone, even if I just get a speck of green. :)
 





Switch

Switch

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The way I see it, sunlight is gonna have to contain a nice quantity of 808nm for it to work.It doesn't have to be coherent does it? :-/
 
GooeyGus

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Switch said:
The way I see it, sunlight is gonna have to contain a nice quantity of 808nm for it to work.It doesn't have to be coherent does it? :-/
Click to expand...

Nope it doesn't  :D People pump with flash-lamps all the time  :cool: :cool:

I haven't had a chance to try this yet, but hopefully tomorrow I'll bust out the magnifying glass and see what I can do  :) What I'm actually worried about it the sunlight being too much and damaging the crystals.
 
Bionic-Badger

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That'll be pretty darn cool actually. I remember on cartoons how they'd make a "laser" by reflecting some sunlight through a ruby or something like that. Of course this is different, but interesting nonetheless.

I do wonder if the other wavelengths will affect the crystal though, possibly cancelling out the wavelength halving.. Perhaps an IR pass filter would help it?
 
Switch

Switch

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Nope it doesn't   People pump with flash-lamps all the time
Click to expand...
No but it has to be 808nm. I thought you can only use flashlamps on yag rods specially doped for pulsed operation :-/

Yeah , an IR pass filter would probably help keep the crystals from being damaged by the other unecessary wavelengths. :p
 
FrothyChimp

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It would be tough but not impossible to generate laser light with sunlight and YVO/KTP. The biggest problem is that the coating on the crystals will transmit 808nm well but not other wavelengths. If a standard YAG rod were used you could take advantage of not only the 808nm in sunlight but also the 525-585nm range of visible. The 808nm is about 1W/m^2 in sunlight when the sun is overhead and the 525-585nm is near 1.5W/m^2. The light could be channeled to the cavity via fiber optics and the total energy available a function of the size of the collector and the cross section of the fiber.

The YVO/KTP setup may not be able to take the sheer amount of energy pumped into it as the amount of non-useful energy would far exceed the useful 808nm the crystal set is designed to absorb. A water cooled YAG rod on the other hand would easily handle the energy. My suspicion is the coatings will be destroyed or the YVO will blitz due to the high concentration. You would have a better chance if you tried using a YAG rod and tried to get 1064nm out of the experiment. Since the mirrors are physically separated from the rod the coatings will not be exposed to the large energy densities (just as in a FL or arc lamp pump). Even if you burn off the AR coatings the rod will still lase.
 
Hemlock_Mike

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Like FC indicates, You may need to filter some of the useless energy away or
you might burn up the experiment.

Mike
 
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disma

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Ya, I don't wanna ruin my good ssy1, so I will probably buy another one when I get ready to try it, I don't have the money right now though. I sure wish it grew on trees. ;D I want to build another ssy1 anyway so I can try it at lower power, I took the q-switch out of my first one.
It would be nice to have a kind of notch filter to allow 808 and 532 through.


Max
 
GooeyGus

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Hmmm... I have a piece of glass from an old remote that I had which only passes IR light. The problem is that I'm not sure how long (or short, I guess) the wavelength needs to be to pass through it. I have some 808 diodes sitting around so I guess I'll see if it passes the light.

Frothy, thanks for the tips. Thats what I was afraid of, that the amount of useless light would just damage the coatings on the crystal assembly. SOO, lets say I got a hold of a yag rod to do this with, maybe even set up in an ssy-1 cavity. Could I just pump the light into the side of the rod and have a reflective chamber of some sort around it, much like a flash lamp would have? How much CW (unless I can manage to pulse the sun  ;D ) power can I pump into one of those ssy-1 rods without damaging it?

EDIT: Oh yeah, I was also thinking about maybe a dye laser pumped by sunlight. I really have no clue when it comes to dye lasers, other than I know they use an organic dye with some sort of energy pump to make laser light. I'm sure it still needs some sort of cavity... any suggestions on where I could read up on doing this, or any lasers I could yank an assembly out of to pump with sunlight?
 
Bionic-Badger

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Hey you might want to check out Sam's FAQ on this... He mentions that the Nd:YOV[sub]4[/sub] is polarization sensitive. So perhaps you're going to need some even better optics to really make this work before you start cracking your crystals. Check out the section on dye lasers too. I'd really like to see a "Jello" dye laser.
 
FrothyChimp

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The YAG rod in an SSY-1 can actually take a fair amount of punishment but remember that rod is doped for pulsed operation. If you try to run it CW without some kind of awesome cooling system you will end up with a broken rod. All you need is a decent CW YAG rod from some broken medical laser somewhere like ebay. Keep your eye open and you might find a good deal every now and again. You don't want a working system as everybody and their dog that fancies themselves some kind of laser expert will be bidding on it. All you need is to harvest the rod and maybe the mirrors. You can always use the SSY-1 optics if you need to since they can be removed very easily.

Side pumping is the preferred method for YAG rods. You would build the cavity and resonator as you would any other YAG system and just not use a flash lamp or arc lamp. You can enclose it all in a reflector but it would just be to shield external components as your sunlight fiber system would look more like an 808nm pump diode bar than a lamp in operation. So your design should include provisions you would normally consider for diode pumped YAG systems.

Your pulses would need to be something on the order of 230us if I remember correctly to match the fluorescence of the rod. Any YAG builders confirm this as I'm doing this from memory? Otherwise if you went the CW direction you would need to keep it cool and bombard it with the full spectrum or a filtered spectrum.

Remember, lasers are a fine balance between gain and loss. The design of the pump light distribution can be critical in whether it will laser or not. You may find you need to install many fiber terminations across a mount running the length of the rod to properly saturate the rod.
 
GooeyGus

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FrothyChimp said:
The YAG rod in an SSY-1 can actually take a fair amount of punishment but remember that rod is doped for pulsed operation. If you try to run it CW without some kind of awesome cooling system you will end up with a broken rod. All you need is a decent CW YAG rod from some broken medical laser somewhere like ebay. Keep your eye open and you might find a good deal every now and again. You don't want a working system as everybody and their dog that fancies themselves some kind of laser expert will be bidding on it. All you need is to harvest the rod and maybe the mirrors. You can always use the SSY-1 optics if you need to since they can be removed very easily.

Side pumping is the preferred method for YAG rods. You would build the cavity and resonator as you would any other YAG system and just not use a flash lamp or arc lamp. You can enclose it all in a reflector but it would just be to shield external components as your sunlight fiber system would look more like an 808nm pump diode bar than a lamp in operation. So your design should include provisions you would normally consider for diode pumped YAG systems.

Your pulses would need to be something on the order of 230us if I remember correctly to match the fluorescence of the rod. Any YAG builders confirm this as I'm doing this from memory? Otherwise if you went the CW direction you would need to keep it cool and bombard it with the full spectrum or a filtered spectrum.

Remember, lasers are a fine balance between gain and loss. The design of the pump light distribution can be critical in whether it will laser or not. You may find you need to install many fiber terminations across a mount running the length of the rod to properly saturate the rod.
Click to expand...

Any suggestions on an easy way to incorporate the fiber into the design? I'm mostly just worried about how to get from lens to fiber, with at least a little bit of efficiency, heh.
 
FrothyChimp

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Something like this maybe?

sunpumpedYAG.jpg
 
GooeyGus

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sweeeeet. Looks good. What about on the other end where I'm actually collecting the sunlight? Can I just focus the lens over the ends of the fiber lines? Also, how much loss is associated with the fiber optic line? For example, If I wanted the 'sun end' of the line outside, but the actual laser inside, am I going to lose a bunch of pump power in the lines? And where can I get some decent fiber optic line? Thanks again :cool:
 
artix

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Maybe you could cool your yag rod with dry ice or liquid oxygen/nitrogen/or what ever else that is insanely cold
 
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