Monolithic Er:YAG Ceramic Waveguide Laser Fabricated by Femtosecond Direct Laser Writing

We demonstrated a monolithic waveguide laser in Er:YAG ceramics fabricated using femtosecond direct laser writing. High-quality Er:YAG ceramics with precisely controlled Er-ion doping were synthesized, providing an optimal medium for laser and amplifier applications. Waveguide structures were inscribed within the ceramics to support low-loss propagation with a large mode area. A monolithic laser cavity was formed by applying dielectric multilayer coatings to the waveguide facets. The waveguide laser, pumped at a wavelength of 1532 nm, achieved 82 mW output and 27% slope efficiency at a wavelength of 1645 nm. Single-longitudinal-mode operation was achieved at 11 mW.