Polymer/silica hybrid waveguide Y-branch power splitter with loss compensation based on NaYF4:Er3+, Yb3+ nanocrystals
Fu Yue-Wu1, Sun Tong-He1, Zhang Mei-Ling2, Zhang Xu-Cheng1, Wang Fei1, †, Zhang Da-Ming1
       

The SEM image of (a) groove on the SiO2 substrate and (b) cross-section of waveguide without upper cladding.