Optical Investigation of the Cu Ions Diffusion into Bulk Lithium Niobate

Comparative Investigations of Nanohardness and Impurity Distribution Profiles of Lithium Niobate Single Crystals Diffusion Doped by Copper Ions

“…A similar complex band was also observed in refs. [], where the crystal coloration caused by the diffusion of Cu ions was studied. According to the results of earlier studies, the spectrum of Cu‐doped LiNbO 3 crystal is formed by two absorption bands: the band with a maximum at 400 nm, caused by the intervalent transition Cu + → Nb 5+ and the band with a maximum near 1000 nm, caused by 2 E g → 2 T 2g intra‐center transition in Cu 2+ ion.…”

“…The data needed for calculations, that is, the oscillator strengths of corresponding optical transitions in copper ions and the refractive indexes for LiNbO 3 at different wavelengths were taken from refs. []. Both absorption bands are considered to have Gauss‐like form.…”

“…The formation of such a layer was confirmed by the XRD studies in ref. [], where it was shown that the surface layer of the annealed in the presence of CuO LN crystal contains nanoparticles with an average sizes of 1.3 and 1.1 nm for X and Z surfaces, respectively. Moreover, the reflexes corresponding to the phases which may contain CuNb 2 O 6 and CuNbO 3 are observed in the diffraction patterns.…”

“…The scanning light beam was propagated perpendicular to the chosen crystallographic direction. It should be noted that this method was successfully used to investigate the spatial distribution of LiNbO 3 coloration caused by high‐temperature reducing annealing …”

“…Moreover, positive modification of properties (optical, electrophysical) of surface and subsurface layers in LN and other oxide crystals by means of diffusion or implantation of metal ions is another important practical problem …”