Nonlinear multiphoton processes in organic and polymeric materials

Bhawalkar, Jayant D.; He, Guang S.; Prasad, Paras N.

doi:10.1088/0034-4885/59/9/001

Cited by 479 publications

(323 citation statements)

References 69 publications

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“…These results not only reveal the fundamental mechanisms associated with such processes, but also have applicability to important applications such as optically limiting devices, multiphoton microscopy, carrier generation deep inside samples via nonlinear absorption, 38,39 and two-photon three-dimensional lithography. 40 …”

Section: Discussionmentioning

confidence: 75%

Multiphoton absorption in germanium using pulsed infrared free-electron laser radiation

et al. 2011

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We report wavelength-and intensity-dependent transmission measurements of intense mid-infrared radiation from the Vanderbilt Free Electron Laser in single-crystal Ge(100) in the wavelength range of 2.8-5.2 μm. This range accesses both the direct and indirect energy gaps in Ge, requiring in each case either two or three photons (2PA or 3PA) for absorption. Large changes in the multi-photon absorption rate are seen at the direct-to-indirect and 2PA-to-3PA transitions. Photon interactions are dominated by free carrier absorption (FCA), primarily due to holes. The entire absorption process is modeled with the two-and three-photon absorption coefficients (β and γ) as fitting parameters.Using newly measured values of the low-intensity FCA cross-sections, we find a best fit to the data at 2.8 µm that is in agreement with theory and previous measurements. We report a ratio of 175 for β across the direct-to-indirect transition, and a ratio of 5 across the same transition for γ. These ratios are independent of systematic variations in free carrier cross-sections and beam diameter. Receipt

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Section: Discussionmentioning

confidence: 75%

Multiphoton absorption in germanium using pulsed infrared free-electron laser radiation

et al. 2011

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“…In most of the 2PA experiments, the amount of absorption is measured by the dissipation of the incident light, which for a single beam 2PA experiment is twice the transition rate. In the case, the 2PA cross-section ͑ gf ͒ of the degenerate process is written as 12,32,33 gf ͑ ͒ = 16 3 …”

Section: Pamentioning

confidence: 99%

“…The two-photon absorption ͑2PA͒ process has attracted growing attention due to its potential applicability in different fields, such as three-dimenstional optical storage, 1 twophoton fluorescence imaging, 2 two-photon photodynamic therapy, 3 and microfabrication. 4 In any application field, compounds having large 2PA cross-sections are desirable, and therefore efforts have been devoted to the development of such materials.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of one- and two-photon absorption spectra of azoaromatic compounds

Silva

Krawczyk

Bartkowiak

et al. 2009

The Journal of Chemical Physics

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Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy J. Chem. Phys. 135, 194307 (2011) Population inversion of molecular nitrogen in an Ar: N2 mixture by selective resonance-enhanced multiphoton ionization J. Appl. Phys. 110, 083112 (2011) Control of vibronic excitation using quantum-correlated photons J. Chem. Phys. 135, 164304 (2011) Resonant two-photon ionization spectroscopy of jet-cooled PdSi J. Chem. Phys. 135, 134308 (2011) Optical purification of a mixture of chiral forms by dimer formation J. Chem. Phys. 135, 124304 (2011) Additional information on J. Chem. Phys. In this study, the one-and two-photon absorption spectra of seven azoaromatic compounds ͑five pseudostilbenes-type and two aminoazobenzenes͒ were theoretically investigated using the density functional theory combined with the response functions formalism. The equilibrium molecular structure of each compound was obtained at three different levels of theory: Hartree-Fock, density functional theory ͑DFT͒, and Møller-Plesset 2. The effect of solvent on the equilibrium structure and the electronic transitions of the compounds were investigated using the polarizable continuum model. For the one-photon absorption, the allowed → ‫ء‬ transition energy showed to be dependent on the molecular structures and the effect of solvent, while the n → ‫ء‬ and → ‫ء‬ ͑n͒ transition energies exhibited only a slight dependence. An inversion between the bands corresponding to the → ‫ء‬ and n → ‫ء‬ states due to the effect of solvent was observed for the pseudostilbene-type compounds. To characterize the allowed two-photon absorption transitions for azoaromatic compounds, the response functions formalism combined with DFT using the hybrid B3LYP and PBE0 functionals and the long-range corrected CAM-B3LYP functional was employed. The theoretical results support the previous findings based on the three-state model. The model takes into account the ground and two electronic excited states and has already been used to describe and interpret the two-photon absorption spectrum of azoaromatic compounds. The highest energy two-photon allowed transition for the pseudostilbene-type compounds shows to be more effectively affected ͑ϳ20%͒ by the torsion of the molecular structure than the lowest allowed transition ͑ϳ10%͒. In order to elucidate the effect of the solvent on the two-photon absorption spectra, the lowest allowed two-photon transition ͑dipolar transition͒ for each compound was analyzed using a two-state approximation and the polarizable continuum model. The results obtained reveal that the effect of solvent increases drastically the two-photon cross-section of the dipolar transition of the pseudostilbene-type compounds. In general, the features of both one-and two-photon absorption spectra of the azoaromatic compounds are well reproduced by the theoretical calculations.

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“…Not only does two-photon excitation require near-IR light which is capable 35 of travelling further through tissues than visible light, but also the nonlinear process restricts absorption to the laser focus. 15,16 Thus greater treatment depths and highly-selective targeting may be achieved by two-photon PDT.…”

Section: Introductionmentioning

confidence: 99%

One- and two-photon activated phototoxicity of conjugated porphyrin dimers with high two-photon absorption cross sections

et al. 2009

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Nonlinear multiphoton processes in organic and polymeric materials

Cited by 479 publications

References 69 publications

Multiphoton absorption in germanium using pulsed infrared free-electron laser radiation

Multiphoton absorption in germanium using pulsed infrared free-electron laser radiation

Theoretical study of one- and two-photon absorption spectra of azoaromatic compounds

One- and two-photon activated phototoxicity of conjugated porphyrin dimers with high two-photon absorption cross sections

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