Characterization of Asymmetrically Fed Er³⁺/Yb³⁺ Co-Doped Double Core Integrated Waveguides

The output signal intensity distribution of several fs-laser written double-core active waveguides was registered. The ratio between cores output powers exhibited a strong dependence on the input pump power when both input pump and signal powers were directly coupled to one of the cores. A model based on the coupled-mode theory which incorporates non-identical cores and longitudinally variable signal gain coefficients was implemented. Simulations based on this model are compared to experiments. A good agreement is achievable if small differences between cores’ parameters (within the manufacturing precision limits) are allowed.