WAVELENGTH DISPERSION OF n_2 BY Z-SCAN TECHNIQUE ON POTENTIAL UV-VIS TUNABLE LASER MATERIALS

摘要

We report the result of the measurements of the nonlinear refractive index n_2 of several host crystals suitable for doping with Cerium (LiBaF_3, LiLuF_4, LiCaAlF_6, SrAlF_5) and with Ytterbium (KMgF_3). Some of these materials have already shown interesting properties for the development of an efficient, wide-band laser in the blue-UV region of the spectrum; some others are promising candidates for this purpose. We performed the measurements using the Z-scan technique, at 1064, 532 and 355 nm, and this last approaches or matches the emission wavelengths of the doped crystals. The samples were also tested for the possible presence of two-photon absorption. All the materials under test have shown a rather low value of the nonlinear refractive index n_2, with a quite weak dispersion, and negligible two-photon absorption at the used wavelengths, due to the fact that their linear refractive index is low, and their energy bandgap is quite high. This characterization is useful in view of the development of high peak power laser devices.