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Multiple wavelengths of "532nm" DPSS lasers. (discussion)

Mattronium

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It has been know by many for some time that some 532nm DPSS lasers produce multiple discrete green wavelengths. Because the information about this is sparse and spread out, this thread will hopefully serve as one place to compile some of the information etc.

The transitions responsible for the lasing in Nd:YVO4 is 4F3/2 --> 4I11/2.
The 4F3/2 has two levels: R1 and R2
The 4I11/2 has six levels: Y1 to Y6.


Currently the wavelengths that I have measured in Nd:YVO4 is: 537 nm, 542 nm, 545 nm, 549.5 nm and ~554 nm

And example of the transitions:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwj517zeytPPAhXIx4MKHY_3CM0QFggeMAA&url=http://physics.utsa.edu/laserlab/publications/papers/2000/Nd_YVO4_2000.pdf&usg=AFQjCNFiUACUdC3gTNcmaSsBHPcld7OEGA&bvm=bv.135475266,d.amc

Another slightly related paper: https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-14-11-4721&id=90064

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http://laserpointerforums.com/f40/589nm-misbehaving-wrong-wavelength-97952.html
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http://laserpointerforums.com/f52/rgv-pointer-xld-868-a-74476.html
http://laserpointerforums.com/f45/multiline-green-pointer-how-possible-60714.html
 
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paul1598419

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Have not seen one of these personally, but i do have a good spectrometer and would like to get my hands one one and do some testing.
 

ultimatekaiser

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Not really. There's lots of green wavelengths. Nd can double to perhaps 8-10 different ones. what info do you want to know? the most obvious ones are 515, 523.5, 526.5, 532, 543, and 561. though there are a couple others I'm sure. I have optics to make several of these...
 

Mattronium

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Not really. There's lots of green wavelengths. Nd can double to perhaps 8-10 different ones. what info do you want to know? the most obvious ones are 515, 523.5, 526.5, 532, 543, and 561. though there are a couple others I'm sure. I have optics to make several of these...
I guess I should be a little more specific.
I'm more focusing on the different wavelengths that come from "532nm" doubled Nd:YVO4 lasers (I believe these are the type found in most low power 532nm lasers). I've mainly been looking at the 4F3/2 --> 4I11/2 since that is where the main 532nm comes from. So I haven't looked at other levels. I haven't been able to find good source for all the energy levels.

What levels are involved in the 526.5nm? Is it reasonable that it could lase in an "ordinary" 532nm laser?
I guess if ~550nm can lase and get doubled then 515, 523.5, 526.5 might be able to also.

If you could point me in the direction of some good data on the wavelengths I would appreciate it.
 
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CaliKirk

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

I found a couple interesting texts with some different transitions..

Nd:YAG




This article was on the different transitions of Neodymium doped glass at different concentrations when pumped with 808nm.




I'd love to figure out exactly what the cause of my 8 line is, personally I think it's something do with crystal contamination but who knows.
 
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diachi

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

I found a couple interesting texts with some different transitions..

Nd:YAG




This article was on the different transitions of Neodymium doped glass at different concentrations when pumped with 808nm.




I'd love to figure out exactly what the cause of my 8 line is, personally I think it's something do with crystal contamination but who knows.





Good job on the searching though! :D
 

CaliKirk

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Sorry Diachi, the next size up that I know how to post is huge, but I made them bigger :)
 
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ultimatekaiser

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Lol. It's nothing quite so complicated. Likely just botched, crappy, overly broadband mirror coatings and an overpumped crystal.

Edit: I have that book btw
 
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paul1598419

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Justin, the Farbray-Perot etalon described in the Google search you referenced is used in YAG lasers that are excited by Xenon discharge lamps and are place between the HR mirror and the YAG rod to select various frequencies of light that are already there by removing all the ones not wanted. it works similar to Brewster's windows in gas lasers. They consist of a glass slide, or glass with parallel surfaces that can be changed either by changing the thickness of the glass, or by tilting the etalon, effectively changing the thickness that way.
 

diachi

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Sorry Diachi, the next size up that I know how to post is huge, but I made them bigger :)

Much better, thanks! :)




Lol. It's nothing quite so complicated. Likely just botched, crappy, overly broadband mirror coatings and an overpumped crystal.

Edit: I have that book btw

Yeah, that was my thinking too - But I never knew there were so many transitions so close together, and transitions that perform well too. Seems there is!

Interesting information all round.
 

CaliKirk

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Justin, the Farbray-Perot etalon described in the Google search you referenced is used in YAG lasers that are excited by Xenon discharge lamps and are place between the HR mirror and the YAG rod to select various frequencies of light that are already there by removing all the ones not wanted. it works similar to Brewster's windows in gas lasers. They consist of a glass slide, or glass with parallel surfaces that can be changed either by changing the thickness of the glass, or by tilting the etalon, effectively changing the thickness that way.
I understand and did label it YAG, I was more posting it to add some data to the thread, sorry
 

ultimatekaiser

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Yeah I'd be more inclined to believe that it's a vanadate but it could be a yag too. both have gotten quite cheap in recent years. I wouldn't be surprised if they put a broader, less reflective coating on it to make it cheaper, resulting in multiple lines lasing side by side and competing for gain.
 
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lazeristasUVISIR

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Yeah I'd be more inclined to believe that it's a vanadate but it could be a yag too. both have gotten quite cheap in recent years. I wouldn't be surprised if they put a broader, less reflective coating on it to make it cheaper, resulting in multiple lines lasing side by side and competing for gain.
Nd:YVO crystal makes lasing polarized without any other optics. For SHG it is quite important. Nd:YAG would be less efficient for small chip type crystals with KTP.
 

ultimatekaiser

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Re: Multiple wavelengths of green DPSS lasers. (discussion)

Nd:YVO crystal makes lasing polarized without any other optics. For SHG it is quite important. Nd:YAG would be less efficient for small chip type crystals with KTP.
You are correct. Although, so does YAG, just to a lesser extent. which is why many of them in high power applications have a wedge on them, to force polarization in one direction, as they are both subject to the Faraday effect. but on a small case like this, it makes little difference, it doesn't make many passes before leaving the crystals. If they doubler is cut correctly, Losses are still pretty minimal in a FP cavity. The gain of the 1064 lin in a vanadate is many times that of the YAG, and it conducts heat better so its stability is also superior, making it an ideal choice. If you have tons of money a Gd vanadate insteaad of a yittrium vanadqate makes a happy a cross between the two.
 




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