Berlin 2012 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 11: Optical and nonlinear optical properties, photonic
DF 11.1: Vortrag
Mittwoch, 28. März 2012, 09:30–09:50, EB 107
Dispersive properties of small polaron-based hologram recording in nominally undoped, thermally reduced LiNbO3 — •Hauke Bruening and Mirco Imlau — Department of Physics, University of Osnabrück, Germany
We recently discovered a new type of hologram recording in nominally undoped, thermally reduced LiNbO3 by means of a single intense ns-laser pulse (λ = 532 nm) yielding short-lived volume phase-gratings with unique features [1]: a diffraction efficiency η of more than 20% in the NIR spectral range (λ = 785 nm), a stretched-exponential relaxation behavior of the grating efficiency with a lifetime in the ms-range at room temperature, an acceleration of the decay with increasing temperature and a pronounced dependence of η on the orientation of the grating vector with respect to the polar c-axis. This type of hologram recording could be successfully modeled by taking into account an optically generated spatial modulation of small bipolarons, bound and free polarons. In this contribution, we face the unique dispersive properties of this type of hologram recording and particularly present our results for probing the gratings in the blue-green spectral range (λ = 488 nm). We show that the contribution of small bound hole polarons has to be considered as well. It can be concluded that a diffraction efficiency of about η ≈ 0.5· 10−4 at the telecommunication wavelength (λ = 1550 nm) can be expected.
*Financial support by the DFG (IM37/5 and INST190/137-1) and DAAD (50445542) is gratefully acknowledged.
[1] M. Imlau et al., Optics Express 19, 15322 (2011)