Atomic displacement and disorder in LiNbO(3) single crystal caused by high-energy (3)He ion irradiation: an x-ray absorption spectroscopy study.

Nb K-edge x-ray absorption fine structure spectra from a single lithium niobate (LN) crystal irradiated with high-energy (3)He ions of 41 MeV and from unexposed crystal as the reference material are compared. The differences in the x-ray absorption near edge structure (XANES) spectra are interpreted by simulating Nb K-edge XANES spectra with the FEFF8.2 code.

Direct visualization of damage cascades in lithium niobate crystals caused by high-energy ions.

Congruently melting undoped lithium niobate crystals are irradiated with 20 MeV (3)He ions which penetrate the entire crystal volume. Radiation damage effects are directly visualized by transmission electron microscopy (TEM) where damage zones with diameters of 4 nm give rise to circular Fresnel fringe contrasts. These regions of modified material, appearing circular in cross-section, are interpreted as damage cascades inflicted by fast Nb and O atoms displaced in knock-on collisions with primary (3)He ions.

Dynamics of holographic recording with focused beams in iron-doped lithium niobate crystals.

Holograms are recorded with focused beams in an iron-doped lithium niobate crystal. The diffraction efficiency shows a maximum after several seconds of recording, unlike in the case of writing with two homogeneous plane waves in the same crystal. This behavior can be attributed to a compensation field caused by incomplete illumination of the crystal.

Incremental holographic recording in lithium niobate with active phase locking.

Angular-multiplexed hologram recording in iron-doped lithium niobate crystals was carried out with near-infrared light. An incremental recording schedule with active phase locking of the light pattern onto the hologram was used. Continuous and reproducible recording of holograms of equal efficiency was achieved, and a hologram multiplexing number, M/#=2 , for a 5-mm-thick crystal was obtained at a 760-nm wavelength of light.

Determination of the absorption cross section of dopants in lithium niobate crystals.

A method is presented to acquire the absorption cross sections of dopants in photorefractive lithium niobate crystals utilizing doubly doped samples. The absorption cross section of one dopant must be well known. By illumination with ultraviolet light, electrons are transferred from one centre to the other.