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 μm diameters were inscribed in both crystals with picosecond (ps) laser pulses at 532 nm of 0.15 μJ 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 μm (with 0.35 mJ pulse energy) and at 1.03 μm (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.