Cladding aod characteristics of the a-axss MgO: LiNbO_3 single crystal fibre

摘要

For more efficient application of LiNbO3 single crystal fibres to non-linear and laser devices, the fibres must be provided with a core-cladding waveguide structure. Cladding the fibre reduces both scattering loss and the number of propagating modes. There are several methods of lowering the refractive index of LiNbO3, such Mg-ion in-diffusion [1-3], ion implantation [4], and proton exchange [5]. We believe, however, that the Mg-ion in-diffusion is the most promising cladding method for LiNbOs crystal fibres, as it not only lowers the ordinary and the extraordinary refractive indices, but also reduces the effective core size and the diffusion process naturally increases the interface smoothness as the depth of diffusion is increased. In this letter, a Mg-ion in-diffusion process is applied to the c-axis MgO:LiNbO3 single crystal fibre with a 60 um diameter. Electron probe microanalysis and Laue X-ray diffraction analysis are employed to characterize the characteristics of the magnesium diffused crystal fibre.