2 photons absorption in a dye

[femtoman]

Voici le lien d'une expérience d'absorption à 2 photons


http://s848664668.onlinehome.fr/Word...orants-divers/

[VDX]

... with what wavelengths will this work?

I have 337, 355, 405, 448-450, 532, 652, 808, 975 and 1064nm lasers ... the 450nm up to 40W on 0,1mm, 808 and 975nm up to 270W on 0,2mm, 1064nm up to 130W CW on 0,02nm or pulsed up to 10kW on 0.03mm spot sizes ...

Viktor

[kecked]

... with what wavelengths will this work?

I have 337, 355, 405, 448-450, 532, 652, 808, 975 and 1064nm lasers ... the 450nm up to 40W on 0,1mm, 808 and 975nm up to 270W on 0,2mm, 1064nm up to 130W CW on 0,02nm or pulsed up to 10kW on 0.03mm spot sizes ...

Viktor

any wavelength will work but getting the peak power up there and the conditions right is a bit harder than it looks.
watch les lab video. 1064 q switched laser makes perfect source and they are cheap. There is an entire field of micrscopy spectroscopy devoted to this. Btw there are multiple types of two photon. And second harmonic is different even though you think it is two,photon.

the reason this works so well is you can integrate the entire signal and plot point by point to build an image unlike confocal where you have to throw away signal. It makes a signal only at one spot so you can ignore scattering.

the 10kw pulsed 1064 should work.

[VDX]

... hmmm ... so best with a fiberlaser for the energy density?

I have one with 30W averaged and fixed pulselength of 200ns ... and another 30W with variable pulselength from 4ns to 350ns (and another CW-type with 130W ... and some more with 50, 60 and 85W).

What's with "adding" several IR-diodes with 975nm and 270W (or up to 400W pulsed) and/or fiberlasers on the same spot? ... or different VIS/UV-wavelengths too?

Viktor

[colouredmirrorball]

Voici le lien d'une expérience d'absorption à 2 photons


http://s848664668.onlinehome.fr/Word...orants-divers/

I have some trouble understanding the physics. Is there really no quantum energy level between the ground and excited states?

Edit: I suppose I could answer my own question: https://en.wikipedia.org/wiki/Two-photon_absorption

There is a "virtual state" formed due to the interactions of the photons with the material. Some kind of weird higher order perturbation-related thing. Very cool that you can observe it!

[femtoman]

I have some trouble understanding the physics. Is there really no quantum energy level between the ground and excited states?

Edit: I suppose I could answer my own question: https://en.wikipedia.org/wiki/Two-photon_absorption

There is a "virtual state" formed due to the interactions of the photons with the material. Some kind of weird higher order perturbation-related thing. Very cool that you can observe it!

Maria Goppet-Mayer the physicist who did her PhD work in 1935 and won a Nobel Prize did not have the opportunity to see the experiment because at the time there was no laser source ...

[femtoman]

... with what wavelengths will this work?

I have 337, 355, 405, 448-450, 532, 652, 808, 975 and 1064nm lasers ... the 450nm up to 40W on 0,1mm, 808 and 975nm up to 270W on 0,2mm, 1064nm up to 130W CW on 0,02nm or pulsed up to 10kW on 0.03mm spot sizes ...

Viktor

You can for 2 photon absorption use only powerfull laser with wavelength longer has 570nm because you cannot find dye under 275 nm !
For 3 photons the 900 nm is the shortest with BBTDOT dye !

[VDX]

... maybe another interesting detail - yesterday I've tested laser-engraving glass with a 355nm UV-DPSS-laser ... it was with pretty common glas plates, normally used for microscopy samples.

Engraving them works pretty good ... the interesting part - while the laser spot is visible like intense "light blue", the borders of the glass plate emits bright "yellow" light! -- could be a hint into DIY disk lasers or something

Viktor