Fabrication and characteristics of the planar and ridge Er³⁺-doped germanate glass waveguides

In this work, the planar and ridge waveguides on the Er³⁺-doped germanate glass were fabricated by the oxygen-ion implantation with the energy of 6.0 MeV and the fluence of 5 × 10¹⁴ ions/cm² and the femtosecond laser ablation with a pulse energy of 3.0 μJ and a scanning speed of 50.0 μm/s. The waveguides were characterized by the m-line setup and the near-field pattern. The formation theory of the planar waveguide was discussed through simulating the energy loss distribution and analyzing the reconstructed refractive index profile. The ion implantation results in a higher-refractive-index layer with a thickness of around 4.8 μm to guide light as a waveguide core and the femtosecond laser ablation leads to two air grooves as claddings in the Er³⁺-doped germanate glass. It is the first report of the O³⁺-implanted Er³⁺-doped germanate glass planar waveguide, to the best of our knowledge. Furthermore, the structural parameters of the O³⁺-implanted and fs-laser ablated Er³⁺-doped germanate glass ridge waveguide have been optimized, compared with the previous work. The planar and ridge waveguides could be used for applications in future integrated optical systems.