two-photon absorption


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two-photon absorption

[‚tü¦fō‚tän əb′sȯrp·shən]
(physical chemistry)
A relatively weak photon absorption and excitation process that occurs when a sufficiently intense light source, such as a laser beam, is used, making it possible for a molecule to absorb simultaneously two photons, each of approximately half the energy (twice the wavelength) normally required to reach an excited state. The probability of a molecule absorbing two photons simultaneously is proportional to the square of the intensity of the input beam.
References in periodicals archive ?
Figure 3 describes the open-aperture z-scan data (80 fs at 830 nm excitation wavelength) resolving a two-photon absorption effect; that is, a diminishing transmittance at the focal plane can be seen.
Expression (6) clearly shows that the inverse of the transmittance ([T.sup.-1]) is a linear function of input irradiance, with the slope related to the two-photon absorption coefficient [beta].
It has been previously reported that two-photon absorption can be switched to saturated absorption in nanostructures by changing the wavelength that gives rise to the nonlinearity [26].
The increase in the pulse repetition rate of the laser system can result in the switch from saturated absorption to two-photon absorption in the sample, allowing attractive applications to be considered.
Solidification is performed in a highly localized volume because of the quadratic dependence of the two-photon absorption probability on the laser intensity.
Two-photon absorption (TPA) is a third-order nonlinear absorption process which is closely related to the imaginary part of nonlinear susceptibility of the material [1].
Then, the electric field modulation effect of two-photon absorption coefficient (TPAC) in HgCdTe photodiode is simulated from a two-band model.
We compared the simulation results with the two-photon absorption experimental results of HgCdTe photodiode [6].
Rana, "Energy limits imposed by two-photon absorption for pulse amplification in high-power semiconductor optical amplifiers," Optics Letters, vol.
(21) have reported decrease of [[beta].sub.eff], with increasing [I.sub.o] for the thiophene oligomers, where they attributed to saturation of instantaneous two-photon absorption.
Previously, efforts to create a silicon laser were thwarted by two-photon absorption which hindered the light amplification.
Importantly, in order to increase even further the potential of the PSs presented in this project, I propose to also excite them via simultaneous two-photon absorption (TPA) in the so-called two-photon excitation PDT (2 PE-PDT).
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