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- Modification of refractive index by a single femtosecond pulse confined inside a bulk of a photorefractive crystal
- Gamaly, Eugene G.; Juodkazis, Saulius; Mizeikis, Vygantas; Misawa, Hiroaki; Rode, Andrei V.; Krolikowski, Wieslaw
- We demonstrate that the interaction of intense femtosecond pulse with photorefractive crystal at conditions close to the optical-breakdown threshold differs drastically from that of long pulse and cw illumination. Our theoretical estimations show that the high number density of excited electrons modifies the dielectric function leading to the transient negative change in the refractive index, Δn/n0∼−10−2 that vanishes on nanosecond time scale. Moreover, the high-frequency laser field, two orders of magnitude larger than the field of spontaneous polarization, prevents the stationary charge distribution during the pulse. The diffusion and recombination of charge carriers continues over a nanosecond time scale, after the end of the pulse. The main driving force for the current after the pulse is the field of spontaneous polarization in the ferroelectric medium: the current terminates when the field of charge separation balances this field. We show here that the stationary modification of refractive index according to this model is then independent of the polarization of the pump light beam, in agreement with experiments, and saturates at Δn≈10−3 in semiquantitative fit to the experimental data.
- Publication type
- Journal article
- Research centre
- Swinburne University of Technology. Faculty of Engineering and Industrial Sciences. Centre for Micro-Photonics
- Physical Review B, Vol. 81, no. 5 (Feb 2010)
- Publication year
- American Physical Society
- Publisher URL
- Copyright © 2010 The American Physical Society. Published version of the paper reproduced here with the kind permission of the publisher for non-commercial purposes only.