Laser Emission from Diode-Pumped Nd:YAG Cladding Waveguides Obtained by Direct Writing with a Femtosecond-Laser Beam

摘要

Cladding waveguides have been realized in Nd:YAG by direct writing with a femtosecond-laser beam. A classical method that inscribes many tracks around the waveguide circumference with step-by-step translations of the laser medium, and a new technique in which the laser medium is moved on a helical trajectory and that delivers waveguides with well-defined walls were employed. Laser emission on the 1.06 μm ~4F_(3/2)→~4I_(11/2) transition and at 1.3 μm on the ~4F_(3/2)→~4I_(13/2) line was obtained under the pump with a fiber-coupled diode laser. Thus, laser pulses at 1.06 μm with energy of 1.3 mJ for the pump at 807 ran with pulses of 12.5-mJ energy were recorded from a circular waveguide of 100-μm diameter that was inscribed in a 5-mm long, 0.7-at.% Nd:YAG single crystal by the classical translation technique. A similar waveguide that was realized in a 5-mm long, l.l-at.% Nd:YAG ceramic increased the 1.06-μm laser pulse energy to 2.15 mJ for the pump pulses of 13.1-mJ energy. Furthermore, a circular waveguide of 100-μm diameter that was inscribed in the Nd:YAG ceramic by the helical-movement method yielded pulses at 1.06 μm with increased maximum energy of 3.2 mJ; the overall optical-to-optical efficiency was 0.24, and the laser operated with a slope efficiency of 0.29. The same device outputted laser pulses at 1.3 μm with energy of 1.15 mJ.