Two-photon absorption coefficient measurements based on widely tunable femtosecond pulses from parametric generation
| Autor: | GianPiero Banfi, Vittorio Degiorgio, D. Fortusini |
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| Rok vydání: | 1998 |
| Předmět: |
Materials science
Extended X-ray absorption fine structure business.industry General Engineering Physics::Optics General Physics and Astronomy Second-harmonic generation Two-photon absorption Condensed Matter::Materials Science Optics Semiconductor Attenuation coefficient Femtosecond Dispersion (optics) business Absorption (electromagnetic radiation) |
| Zdroj: | Pure and Applied Optics: Journal of the European Optical Society Part A. 7:361-372 |
| ISSN: | 1361-6617 0963-9659 |
| Popis: | We discuss an experimental arrangement for fast and reliable measurements of the two-photon absorption coefficient and its wavelength dispersion. Widely tunable pulses, with sufficient power (and therefore intensity) to detect the nonlinear absorption in samples with a small (L is the sample thickness), are provided by travelling-wave parametric generation. The short time duration of the pulses minimizes the accumulation of carriers excited by two-photon absorption (TPA), or by an eventual linear mechanism, which could otherwise produce an appreciable additional absorption which would be difficult to take account of. To produce a relative calibration of the set-up, we suggest the use of second-order crystals which, when phase-matched for second harmonic generation, mimic a two-photon absorber. We give examples of measurements on semiconductors and on organic thin films, and we report the TPA spectra of CdTe and CdSe semiconductor nanocrystals in a glass matrix. |
| Databáze: | OpenAIRE |
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