Waveguiding microstructures in Nd:YAG with cladding and inner dual-line configuration produced by femtosecond laser inscription

We demonstrate a new design of waveguiding microstructure, which contains both cladding and inner dual-line configurations, in Nd:YAG laser crystals inscribed by femtosecond laser processing. Based on this prototype, a few "cladding + dual-line" hybrid structures with different parameters have been successfully manufactured in Nd:YAG. The waveguide lasing at 1.06 μm has been realized in the hybrid structures under 808-nm optical pump. Compared to the single dual-line waveguides, the dual-line core in hybrid configuration benefits from the large-area pump from the external cladding, reaching an enhancement of 26% on the maximum output power and of 24% on the slope efficiency of the waveguide lasing. In addition, the symmetric stress field of external cladding structure produces anisotropic stress field in the inner cores, supporting guidance along both TE and TM polarizations, thus differing significantly from the single dual-line waveguides.