CLADDING WAVEGUIDES REALIZED IN Nd:YAG LASER MEDIA BY DIRECT WRITING WITH A FEMTOSECOND-LASER BEAM

We report on realization of buried cladding waveguides in Nd:YAG single crystal and ceramic media by direct femtosecond (fs)-laser writing technique. A classical technique that moves the laser medium transversally to the fs-laser beam, as well as a new scheme in which the laser medium has a motion on a helical trajectory during the inscribing process was used. The waveguides laser emission performances at 1.06 and 1.3 µm have been investigated under the pump at 807 nm with a fibercoupled diode laser that was operated both in quasi-continuous wave (quasi-cw) and in cw regimes. Laser pulses with energy of 3.45 mJ at 1.06 µm and of 1.05 mJ at 1.3 µm (with overall optical-tooptical efficiency of 0.26 and 0.08, respectively) were obtained from a 50 µm in diameter circular waveguide that was inscribed by the helical-moving techniques in a 5.0-mm long, 1.1-at.% Nd:YAG ceramic medium. Characteristics of the laser emission recorded in cw operation are discussed.