Investigation of nonlinear absorption processes with femtosecond light pulses in lithium niobate crystals
| Autor: | Oliver Beyer, Karsten Buse, B. Sturman, Hung-Te Hsieh, Demetri Psaltis, Dominik Maxein |
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| Rok vydání: | 2004 |
| Předmět: |
Materials science
Extended X-ray absorption fine structure Absorption spectroscopy business.industry Lithium niobate Absorption cross section Physics::Optics Two-photon absorption chemistry.chemical_compound Optics chemistry Femtosecond Transmission coefficient Atomic physics business Absorption (electromagnetic radiation) Caltech Library Services |
| Zdroj: | Physical review. E, Statistical, nonlinear, and soft matter physics. 71(5 Pt 2) |
| ISSN: | 1539-3755 |
| Popis: | The propagation of high-power femtosecond light pulses in lithium niobate crystals (LiNb O3 ) is investigated experimentally and theoretically in collinear pump-probe transmission experiments. It is found within a wide intensity range that a strong decrease of the pump transmission coefficient at wavelength 388 nm fully complies with the model of two-photon absorption; the corresponding nonlinear absorption coefficient is beta(p) approximately = 3.5 cm/GW. Furthermore, strong pump pulses induce a considerable absorption for the probe at 776 nm. The dependence of the probe transmission coefficient on the time delay Delta t between probe and pump pulses is characterized by a narrow dip (at Delta t approximately = 0) and a long (on the picosecond time scale) lasting plateau. The dip is due to direct two-photon transitions involving pump and probe photons; the corresponding nonlinear absorption coefficient is beta(r) approximately = 0.9 cm/GW. The plateau absorption is caused by the presence of pump-excited charge carriers; the effective absorption cross section at 776 nm is sigma(r) approximately = 8 x 10(-18) cm(2). The above nonlinear absorption parameters are not strongly polarization sensitive. No specific manifestations of the relaxation of hot carriers are found for a pulse duration of approximately = 0.24 ps. |
| Databáze: | OpenAIRE |
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