Using flourescence to change wavelength

[Townes]

Would using flourescent "colour filters" work if they were added to a violet/UV laser?

 

[pullbangdead]

It wouldn't be coherent light coming out of the material that was fluorescing, if you're just using a simple fluorescing filter.

Something close to the same idea is optical pumping, but for that you have to have a cavity and such things. It's not as simple as just fluorescing a material, but it's kindof the same idea.

If you think of optical pumping as being a laser effect, then using a simple fluorescing material would be likened to an LED.

 

[Bionic-Badger]

A filter, by definition, simply blocks certain wavelengths from passing through, so it really doesn't change wavelengths. Likewise, when a material fluoresces, the molecules absorb the light, and reemit it at a lower wavelength. So a fluorescent material can't be used to change the "color" of laser light, or at least keep it coherent like a laser.

 

[pullbangdead]

A filter, by definition, simply blocks certain wavelengths from passing through, so it really doesn't change wavelengths.  Likewise, when a material fluoresces, the molecules absorb the light, and reemit it at a higher wavelength/lower energy.  So a fluorescent material can't be used to change the "color" of laser light, or at least keep it coherent like a laser.

 

[Bionic-Badger]

Actually, I should've used "longer" instead of "lower"--or "higher" for that matter--which is really associated with frequency not wavelength.

 

[brtaman]

Actually from my limited understanding of dye lasers (usually well mostly pumped by nitrogen lasers), they work on the principle of fluorescence. However, as somebody already mentioned, it is not as simple as it may seem (just point through die), as they also use mirrors to oscillate the light to increase power.

TEA lasers (3XXnm, i can't recall) which are actually quite easy to build (quite hard to get working nicely) can be used to pump a dye and get whatever frequency the die is made for. I remember a website by a Croatian professor who made a very nice TEA laser and used it to pump a die (even directly IIRC), he got a wavelength in the orange-yellow region based on his pictures. However, all pump sources for dye lasers are UV and pulsed (IIRC), would be interesting to use a 405nm to do it though.

 

[ben74]

Might be a bit off topic, is there a chemical or something to make the blu-ray a little fluorescent in the air?

 

[rog8811]

Someone once tried adding a flourescent die to fogger fluid....It didn't work, IIRC it just made ordinary fog.

Regards rog8811

 

[brtaman]

Well if anyone is interested I found the site: http://www.milankarakas.org/pub/experiments.html


Using the TEA for dye:
http://www.milankarakas.org/pub/TEA_improvement/TEA_Laser_improvement.html

 

[Townes]

A filter, by definition, simply blocks certain wavelengths from passing through

Hence the quotation marks.

I have 2 circular, transparent, flourescent, plastic discs about 1.5 inches in diameter and 0.25 inches thick. One of them greenish yellow and the other orange. They are lying around somewhere but I can't find them. If I find them, I'll post pics.

Well if anyone is interested I found the site

Nice find, brtaman. Looks like it worked for that guy. I was thinking of trying it with my green laser and because the discs are transparent, there won't be any scattering from opaque particles. I bet the photons aren't in phase though.

 

[Bionic-Badger]

The problem with those dye lasers is that they need a very powerful (pulsed) light source. You can't get that with a diode. Even those greens have very poor efficiency in their frequency doubling crystals.

 

[wolfblue]

I think a CW diode pumped dye laser would work. But it would be a beast to build. You would need 1-2 watts of blu-ray all focused to a very tiny spot. Then a high pressure pump and a tiny nozzle blasting dye through mid air, where the blu-rays converge. Collect and cool the dye, it would probably get hot and degrade. Then curved dielectric mirrors ($$$) aligned with each other and focused on that same tiny spot. And the dye ($$$)

And then you get just a few mW of a new color.

--JFH