Advanced characterization of color centers lightemitting waveguides induced in lithium fluoride crystals by femtosecond laser

Waveguiding light-emitting strips have been written in a blank LiF crystal with a femtosecond laser, by translating the sample under the pulsed focused beam. Light guiding through these buried micro-structures was observed at several wavelengths between 458 and 1550 nm. Visible photoluminescence spectra of aggregate F₂ and F₃⁺ laser active color centers were measured. The refractive index increase, estimated of the order of 10^-4 in the visible and near-infrared spectral intervals, is consistent with the stable formation of electronic point defects in LiF. These results are promising for the realization of miniaturized optical waveguiding solid-state amplifiers and lasers based on color centers.