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Frequency doubling

PyroJackal

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Nov 12, 2021
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Hello, I'm new to this forum, but today I was thinking if we could put a KTP crystal (like the ones in green DPSS lasers) on a say 808 nm laser diode to double its frequency and make the output purple, or we could put it on a 720 nm LD to make 360 nm UV light. Is that possible?
 



Sowee7

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actually it is possible to double 808nm and 720nm, ive gotten 404nm from 808nm when i was messing around with very high power pump diodes and some LBO, but you would either need a very high power pump, or a slightly lower powered pump and a few mirrors/other optics
 

CurtisOliver

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You won’t be able to use KTP for outputting short wavelengths. If we could, 473nm would be more efficient and cheaper to obtain. LBO, BBO and BiBO are typically used for producing <500nm. BiBO has the best efficiency but it is expensive and hard to get hold of. LBO is by far the most common crystal to use other than KTP. Crystals require phase matching, so you need to know the angle of which to orient the crystal to produce doubled output. Some crystals are cut with the phase matching angle already considered, so they are easy to use. Bare in mind that with directly doubled diodes the output beam will be dependent on the input beam specs. So poor beam quality in will have poor beam quality out.
 

PyroJackal

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You won’t be able to use KTP for outputting short wavelengths. If we could, 473nm would be more efficient and cheaper to obtain. LBO, BBO and BiBO are typically used for producing <500nm. BiBO has the best efficiency but it is expensive and hard to get hold of. LBO is by far the most common crystal to use other than KTP. Crystals require phase matching, so you need to know the angle of which to orient the crystal to produce doubled output. Some crystals are cut with the phase matching angle already considered, so they are easy to use. Bare in mind that with directly doubled diodes the output beam will be dependent on the input beam specs. So poor beam quality in will have poor beam quality out.
So I could use it to double the frequency from a 1160 nm LD to make 580 nm yellow light?
 

CurtisOliver

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Theoretically you could. It has been done.
It wasn’t using KTP in that case however. It was a Yb-fiber doubled by MgO: PPLN.
 

kecked

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Good luck. Been chasing doubled yellow for a very long time. As he said fiber works but try getting someone to sell it to you under 50k. It’s used for eye surgery.
 

Sowee7

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Good luck. Been chasing doubled yellow for a very long time. As he said fiber works but try getting someone to sell it to you under 50k. It’s used for eye surgery.
uhh i think i found something
 

kecked

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they have a lot of nice stuff but too expensive for me. I also want more in the 575nm range.
 




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