Efficient Optical Waveguiding Enabled by Focused Proton Beam Writing in Nd:YCOB Crystal

We report on microfabrication and optical characterization of buried channel waveguides defined in Nd:YCOB crystal by focused proton beam writing (PBW). In the fabrication process, the focused proton beam irradiation creates a local material modification region with geometrically symmetric positive index changes at the end of the proton trajectory, where efficient optical waveguiding can be locally supported within a fiber-like channel structure. The impact of the proton fluence (with different values ranging from 1015 to 1016 cm−2) on the optical waveguiding performance is well studied. The experimental results of the optical waveguide properties are in fairly good agreement with the simulation results.