Beyer, O. and Maxein, D. and Buse, K. and Sturman, B. and Hsieh, H. T. and Psaltis, D. (2005) Investigation of nonlinear absorption processes with femtosecond light pulses in lithium niobate crystals. Physical Review E, 71 (5). Art. No. 056603. ISSN 1539-3755. http://resolver.caltech.edu/CaltechAUTHORS:BEYpre05
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The propagation of high-power femtosecond light pulses in lithium niobate crystals (LiNbO3) 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 betap~=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 Deltat between probe and pump pulses is characterized by a narrow dip (at Deltat~=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 betar~=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 sigmar~=8×10^–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 ~=0.24 ps.
|Additional Information:||©2005 The American Physical Society (Received 20 December 2004; published 10 May 2005) Financial support from the Deutsche Telekom AG, from the Deutsche Forschungsgemeinschaft (Award No. BU 913/13-1), and from the NSF (Engineering Research Centers Program for Neuromorphic Systems Engineering under Award No. EEC-9402726, NSF-Germany Cooperative Research Grant No. INT-0233988) is gratefully acknowledged.|
|Subject Keywords:||lithium compounds; light propagation; absorption coefficients; high-speed optical techniques; nonlinear optics; two-photon processes; hot carriers|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||13 Mar 2006|
|Last Modified:||26 Dec 2012 08:47|
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