Buried Depressed-Cladding Waveguides Inscribed in Nd³⁺ and Yb³⁺ Doped CLNGG Laser Crystals by Picosecond-Laser Beam Writing

Buried depressed-cladding waveguides were fabricated in 0.7-at.% Nd:Ca3Li0.275Nb1.775Ga2.95O12 (Nd:CLNGG) and 7.28-at.% Yb:CLNGG disordered laser crystals grown by Czochralski method. Circular waveguides with 100 mu m diameters were inscribed in both crystals with picosecond (ps) laser pulses at 532 nm of 0.15 mu J energy at 500 kHz repetition rate. A line-by-line writing technique at 1 mm/s scanning speed was used. Laser emission at 1.06 mu m (with 0.35 mJ pulse energy) and at 1.03 mu m (with 0.16 mJ pulse energy) was obtained from the waveguide inscribed in Nd:CLNGG and Yb:CLNGG, respectively, employing quasi-continuous wave pumping with fiber-coupled diode lasers. The waveguide realized in RE3+-doped CLNGG crystals using ps-laser pulses at high repetition rates could provide Q-switched or mode-locked miniaturized lasers for a large number of photonic applications.