Distributed feedback laser action in sol-gel glass symmetric waveguides

Symmetric waveguide lasers were prepared by the sol-gel method on glass substrate using rhodamine dye-doped zirconia films as the active guiding layer. The cover layer was titania-silica with a refractive index matching that of the glass substrate. Distributed feedback laser action was induced in the waveguide structure by the crossing beams of a frequency-doubled neodymium:YAG laser. Tunable laser action was achieved in the symmetric waveguide with guilding film thickness as small as 0.12 mum. Lasing was not obtained for asymmetric waveguides of the same thickness. Lower pump threshold was generally observed for symmetric waveguide lasers. The dispersion characteristics of the waveguide lasers were in excellent agreement with thin-film optical waveguide theory, demonstrating the high optical quality of the sol-gel waveguide structure.