Dear professors and colleagues,
I am going to to study effect of the two photons absorption in Safranin O. Safranin O is organic material, so I think that the power needed to activate this effect doesn't need to be too high. However, the two photons absorption is a third-order nonlinear optical effect, so it is usually implemented with high-power pulsed lasers. I cannot afford to buy high-power pulsed lasers. So, can I stimulate effect of two photons absorption in safranin O by continuous wave laser (808 nm or 1064 nm)? And how much is the required power of laser? I hope the colleagues who have experience in this experiment share me useful information.
I look forward to hearing from you. Thanks in advance.
Yours sincerely.
- Dear Nguyen, TPA is not threshold effect (in opposite lasing), therefore TPA could take place on arbitrary intensity but registration and study has to be relevant. Most simple way to follow TPA (even 3 PA) with excited luminescence. In the case of usage CW laser emission about 1W after focusing of the beam up to (10-50) mkm You realize intensity approximately some MW that enough even for lasing on dye solutions (but with cavity) and ... and boiling of given solution due to heating by laser emission. However there is another way to monitor single photons luminescence at low power cw excitation - to built single photon counting system. So compare two way - powerful nanopulse laser or single photon counting system for study - and be successful in your choice.
Dear Prof.Eugene A.Tikhonov , thank you for your answer. I am going to buy some laser to implement two photon absorption. However, I don't know required power of laser to active this effect. Could we do with power of laser < 100 mW on organic material Safranin O?
Thank you Ban A.Naser for your answer. Have you ever implemented this experiment? If yes, you can share me some useful information.
Dear Nguyen, I beg You pardon, please read with attention my above given advice.. or at least tell us for what task You are going to apply TPA excitation then it would be possible to figure out correctly what laser beam intensity W/mm2 You was needed...
Dear Prof.Eugene A.Tikhonov , thank You for again your useful information. I am investigating two photon absorption in organic photosensitizers for photodynamic theraphy applications, such as Safranin O, Chlorophyll, Photofrin...We only need active effect. It's difficult for us to buy 1 W laser in Vietnam as you mentioned. Thank You
Two-photon absorption in a semiconductor allows for the absorption of light even if the photon energy is below the band gap energy. In a dielectric material or a semiconductor, two-photon absorption can normally occur only if the photon energy is at least half the band gap energy.
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