532nm-pumped Rhodamine 6G

[goninanbl00d]

In a small curvette (1x1.5cm base diameter), would it be possible to pump it using 300mW or so of 532nm green and get some form of output? (assuming a proper HR and OC are used)

Everyone I've talked to seems to have a different opinion on this.

In CW mode, there will be need for a flow within the curvette, quite naturally. However, ignore that for now- there'll be no point if you can't even get output.

 

[Benm]

How do you envision this setup?

Would you like the beam to 'extend' the green beam, so pump it from the HR side? I suppose this is feasible if you can obtain a coating/mirror that is HR for the fluorescing frequency, but AR (or at least decently transparant) for the 532 pump light. The OC should be exactly the other way around.

Or would you pump it from the side? In the latter case you would need a beam that is quite wide but not tall. Something similar is done using flashlamps and optics that bundle their light into a line within the lasing medium.

 

[goninanbl00d]

I'll post up the sheet I have tomorrow. It's got the full diagrams and stuff on it.

But it will be side pumped in a small curvette, with a proper glass line-generating optic to expand the green beam to the diameter of the curvette.

 

[Cyparagon]

That beam will be all over the place. "It's 808nm... now it's 1064. Wait: 532. Damn, now it's 610; what an asshole"

 

[LSRFAQ]

That beam will be all over the place. "It's 808nm... now it's 1064. Wait: 532. Damn, now it's 610; what an asshole"

I hate to rain on your parade, but no lasing in a low flow cell with a CW pump.

For cw lasing of a dye you need flow to avoid triplet state quenching. You need to get the dye out of the lasing area very fast, or the molecules that just lased become adsorbers and block lasing. The time period you have is about a microsecond to clean out the lasing volume.

Typical dye jets are a 1 mm wide flat stream pumped at 60-80 PSI. The one CW dye laser I have thresholds at 3.6 watts.

If you had a qswitched pump with high peak power, you can switch to a low flow cell. Ie a 7 nanosecond pulse from a fast, doubled, Nd;YAG expends all its energy lasing before the triplet states form in the molecule. This is why a nitrogen laser with its high peak power can lase a dye. A small nitrogen laser might have a tenth of a milliwatt average power, but can have a 20-100 kilowatt peak power.

So your option as a hobbyist is to build a nitrogen laser to pump your dye cell, the cw 532 will just make it glow. Even if you gated your 500 mW on and off in a microsecond, you still would not have enough peak power to lase.

Your other option would be something like this:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16669
A large xenon flashlamp firing a few shots a minute.

If you wish to do a flashlamp pumped laser, the Lankard design in Scientific American magazine works, but it would work better if you placed a IR adsorber around the lamp to damp the thermal shockwave from lamp, which tends to quench lasing.

Sorry,

Steve

 

[goninanbl00d]

I hate to rain on your parade, but no lasing in a low flow cell with a CW pump.

For cw lasing of a dye you need flow to avoid triplet state quenching. You need to get the dye out of the lasing area very fast, or the molecules that just lased become adsorbers and block lasing. The time period you have is about a microsecond to clean out the lasing volume.

Typical dye jets are a 1 mm wide flat stream pumped at 60-80 PSI. The one CW dye laser I have thresholds at 3.6 watts.

If you had a qswitched pump with high peak power, you can switch to a low flow cell. Ie a 7 nanosecond pulse from a fast, doubled, Nd;YAG expends all its energy lasing before the triplet states form in the molecule. This is why a nitrogen laser with its high peak power can lase a dye. A small nitrogen laser might have a tenth of a milliwatt average power, but can have a 20-100 kilowatt peak power.

So your option as a hobbyist is to build a nitrogen laser to pump your dye cell, the cw 532 will just make it glow. Even if you gated your 500 mW on and off in a microsecond, you still would not have enough peak power to lase.

Your other option would be something like this:
Large High Power Xenon Strobe Tube-The Electronic Goldmine
A large xenon flashlamp firing a few shots a minute.

If you wish to do a flashlamp pumped laser, the Lankard design in Scientific American magazine works, but it would work better if you placed a IR adsorber around the lamp to damp the thermal shockwave from lamp, which tends to quench lasing.

Sorry,

Steve

Ouch, that seems much worse than I expected. A microsecond? :O :yabbmad:

I had planned to use several pumps in parallel, and drilling out the bottom of the curvette to allow dye to flow across it. The curvette would have been firmly supported in an aluminum brace to ensure it doesn't explode.

The whole plan was that I would try and push as much dye through the curvette as humanly possible, with readily accessible components.

So, it's not going to work. Oh well, it was fun playing around with the idea

Anyway, thanks Steve for your help. I can post up the sheet with the scribbles on it, if anyone wants to see it.

 

[Benm]

Good insights here!

For cw lasing of a dye you need flow to avoid triplet state quenching. You need to get the dye out of the lasing area very fast, or the molecules that just lased become adsorbers and block lasing. The time period you have is about a microsecond to clean out the lasing volume.

Do you know the half-life of the triplet state?
As I understand that can be reduced using chemical additives, but i wonder if its decay could also be aided by light - if there is any non-forbidden transition out of the triplet state at all.

 

[LSRFAQ]

Good insights here!



Do you know the half-life of the triplet state?
As I understand that can be reduced using chemical additives, but i wonder if its decay could also be aided by light - if there is any non-forbidden transition out of the triplet state at all.

Typically 300 nS.

COT-Cyclooctatetraene is probably not getting shipped to your doorstep UPS. Nasty stuff.

Exciton should tell you what you want to know.

There have been papers about very low power cw IR dyes pumped by 650 nm diodes, but going deep red to IR kind of defeats the purpose, does it not?

see :: Pulslaser :: for the flashlamp pumped method. Click on Farbstoff.

Steve

 

[goninanbl00d]

Typically 300 nS.

COT-Cyclooctatetraene is probably not getting shipped to your doorstep UPS. Nasty stuff.

Exciton should tell you what you want to know.

There have been papers about very low power cw IR dyes pumped by 650 nm diodes, but going deep red to IR kind of defeats the purpose, does it not?

see :: Pulslaser :: for the flashlamp pumped method. Click on Farbstoff.

Steve

On this topic, what about if the pump laser was pulsed? Would that make it possible to get some output in a small curvette using a 'slow-flow' pump?