In this paper, we present results of experimental and theoretical studies of the formation of refractive index voxels in photorefractive crystals with high power femtosecond laser pulses. We used 150 fs pulses at 800 nm wavelength tightly focused inside the iron-doped lithium niobate crystal in a single shot regime. We discuss various aspects of the recording/erasing process including mechanisms of laser absorption, electron excitation and recombination, formation of charge separation field, as well as methods for control of the size and longevity of the refractive index changes. The analysis shows that the photovoltaic effect is mainly responsible for these changes. The presented results suggest the possibility of suitability of properly chosen femtosecond pulses for fast 3D write-read-erase optical memory application.
Proceedings of the European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference (CLEO/Europe-IQEC), Munich, Germany, 17-22 June 2007