Question about Yellow lasers

[ZRaffleticket]

Okay, as some of us know there are DPSS (589nm and 593.5nm) yellow lasers, and there are some yellow HeNe's and krypton lasers.

I did some searching on the internet, and did some small comparisons with my laser chart and found... 588nm. Yep, approx 1nm (.93nm more precisely) shorter than the current DPSS process.

In 589nm lasers and 593.5nm lasers, two different laser lines must be generated from Nd:YAG and both sent into a crystal set. If anyone reading knows a lot about DPSS, this is EXTREMELY inefficient. Green lasers double one line, making them more efficient (in most cases).

Looking through coherent's OPSL page I found 588nm. I wasn't familar with this so I researched more, and came to the conclusion (on my own) that either what they did was took Nd:YVO4 and doubled the 1176nm line, or took Nd:GdVO4 and doubled it's 1176nm line.

My question is: Why don't we see this done often? Are the coatings too tough to produce? Is Nd:YVO4/Nd:GdVO4 inefficient in that line? (if it's Nd:GdVO4 is it very expensive?)

 

[Trevor]

OPSL stands for "optically pumped semiconductor laser."

They're not using laser crystals at all. They're using a die.

It's a relatively new technology and is quite expensive.

Green lasers are not efficient because it's doubling one line. Green lasers are efficient because the 1064nm line dominates in Nd:XXXX.

Trevor

 

[ZRaffleticket]

Aye, then it looks like coherent is NOT going to be a source for these
However, I found this in my research. So a Raman laser is a laser that has to do with scattering...?

 

[Trevor]

Coherent is prettymuch it for OPSL lasers right now. Chinese companies can't do it yet.

I'll leave your question about that other laser to Bluefan or Cyparagon. Super exotic DPSS is not my area of expertise.

Trevor

 

[Bluefan]

Raman scattering is a very interesting process, it's called scattering because it's not a parametric process. Technically second harmonic generation is also a form of scattering, but it's usually mentioned on it's own.

I don't know the details of Raman amplification, I think it's the same as normal raman scattering but with the decay from the virtual energy level being coherent with an incoming photon, thus generating coherent amplification. Normal raman scattering has an efficiency of 0.00001% compared to normal scattering, so Raman lasers aren't practical or useful by any means yet. Raman scattering doesn't have to be in a solid, in gasses it's quite common and it's also possible in liquids. I don't know if non-solid state raman lasers are made though, I only know if Si based raman lasers.

On the DPSS lasers: 594nm lasers and 589nm lasers are different, one is a less efficeint line doubled, the other is SFG, sum frequency generation. (EDIT: whoops, both are SFG) SFG is less efficient than SHG, for SHG the incoming fields are of the same frequency and thus higher intensity that two separate fields of different frequencies. This means a factor of 4 in efficiency (factor of 2 in E fields means factor 4 in Intensity). Not that bad, but SFG also involves a second less efficient spectral line where simply doubling a weaker line doesn't have the 4x disadvantage.

 

[rhd]

On the DPSS lasers: 594nm lasers and 589nm lasers are different, one is a less efficeint line doubled, the other is SFG, sum frequency generation.

Bluefan:

Are you certain?

I was pretty sure that both were SFG. I didn't think either was SHG (doubling). I thought the both used 1064, and then SFG'd with slightly different second wavelengths in the 1300s somewhere.

Trevor:

Try finding a used 561nm DPSS labby, and it's tough to do so for under $500. Conversely, I'm excited to be waiting for a used 488nm OPSL labby that I grabbed for $200.

So while retail OPSL may be astronomical, in the used market, I'm not sure it's that much worse than exotic DPSS.

ZRaffel:

"Why don't we see this done often?"

Well, we sort of do. I mean, the fact that companies like Coherent and CNI have these things on their websites is pretty astounding, in that they're not really a consumer good. They're not even a "really nerdy consumer" good. They're pretty darn narrowly targeted at very specific scientific applications.

So how do you quantify "often" ?

I think just seeing it presented *somewhere* as a purchasable product by one company, is pretty impressive for such a niche item.

 

[Trevor]

I was pretty sure that both were SFG. I didn't think either was SHG (doubling). I thought the both used 1064, and then SFG'd with slightly different second wavelengths in the 1300s somewhere.

I was pretty sure that it was this:

1064nm + 1342nm = 593.5nm
1064nm + 1319nm = 589nm

Bluefan, correct me if I'm wrong?

Try finding a used 561nm DPSS labby, and it's tough to do so for under $500. Conversely, I'm excited to be waiting for a used 488nm OPSL labby that I grabbed for $200.

So while retail OPSL may be astronomical, in the used market, I'm not sure it's that much worse than exotic DPSS.

The Sapphires on ebay for $200 I believe were end-of-life heads and lacked power supplies. There's a complete system for $450, but after seeing how the Proteras performed as end-of-life heads, I'd stay away from it.

Used scientific lasers are usually used up.

Trevor

 

[Bluefan]

I was pretty sure that it was this:

1064nm + 1342nm = 593.5nm
1064nm + 1319nm = 589nm

Bluefan, correct me if I'm wrong?

I looked it up and indeed both yellows are SFG, I must've mixed up the involved process with that of other wavelengths, I didn't check it when I posted, my bad. It's late here.

 

[Trevor]

I looked it up and indeed both yellows are SFG, I must've mixed up the involved process with that of other wavelengths, I didn't check it when I posted, my bad. It's late here.

Well... my 1319 + 1064 hypothesis came from looking at the Nd:YAG lines and summing them until something worked.

I'd take your judgment over my guess any day...

Trevor

 

[Sigurthr]

Incase anyone is wondering how 1064nm + 1342nm = 593.5nm and how 1064nm + 1319nm = 589nm... it's not simple addition.

1/((1/1064) + (1/1342)) = 593.4696nm
1/((1/1064) + (1/1319)) = 588.9282nm

 

[Trevor]

Incase anyone is wondering how 1064nm + 1342nm = 593.5nm and how 1064nm + 1319nm = 589nm... it's not simple addition.

1/((1/1064) + (1/1342)) = 593.4696nm
1/((1/1064) + (1/1319)) = 588.9282nm

Physically, the process involves the summing of photon energies - not just magically taking the reciprocal of the wavelength.

Trevor

 

[Sigurthr]

Yes, haha. Wouldn't that be great though!

No, lol, I meant for those reading along going "1064 + 1342 = 2406..WTF??!!!".

 

[rhd]

The Sapphires on ebay for $200 I believe were end-of-life heads and lacked power supplies. There's a complete system for $450, but after seeing how the Proteras performed as end-of-life heads, I'd stay away from it.

Used scientific lasers are usually used up.

Sure, but I was just trying to draw a comparison between DPSS and OPSL resale prices in general. I think DPSS would have the same end-of-life issues, yet it's still near impossible to find a used exotic DPSS wavelength under $500.

That said, in the OPSL world, 488 might not be exotic - that's sort of the 532nm of OPSL.

 

[Bluefan]

Physically, the process involves the summing of photon energies - not just magically taking the reciprocal of the wavelength.

Trevor

It isn't called Sum Frequency Generation for nothing, the frequency is directly proportional to the photon energy. The wavelength is determined by the frequency and propagation speed, although usually c is taken for that.

 

[BShanahan14rulz]

Incase anyone is wondering how 1064nm + 1342nm = 593.5nm and how 1064nm + 1319nm = 589nm... it's not simple addition.

1/((1/1064) + (1/1342)) = 593.4696nm
1/((1/1064) + (1/1319)) = 588.9282nm

Frequency = v/wavelength, v=C we take as constant when workign with light, simplify math by using 1

It IS simple addition, innit? :thinking: Well, almost.

 

[ZRaffleticket]

Simple math-wise. Physics wise not so much.