Cladding waveguide fabrication by femtosecond laser in Yb-doped phosphate glasses

Cladding waveguides near sample surface were investigated in Yb-doped phosphate glass using a femtosecond laser. The propagation of LP11-mode and dark-hollow beam was achieved using the circular cladding waveguides by adjusting the pulse energy and diameter of the cladding structure without inducing any damage tracks to the guiding core. Furthermore, semi-circular cladding waveguides with large-area and uniform-intensity modes were fabricated just below the glass surface. The working mechanism of the surface waveguide was clarified by analyzing the influence of the writing depth, which involves an overlapping between the mode at the upper end of the damage line and the mode adjacent to the glass interface. Finally, we successfully operated a 1030 nm laser by pumping the surface cladding waveguide at 976 nm.