Enhanced spectroscopic properties at 1.5 μm in Er3+/Yb3+-activated silica-titania planar waveguides fabricated by rf-sputtering

Er3+/Yb3+-codoped 94SiO2-6TiO2 planar waveguides, with 1 mol% Er and molar ratio Yb/Er = 2, were fabricated by rf-sputtering technique. All waveguides were single-mode at 1550 nm. An attenuation coefficient of 0.5 dB/cm at 632.8 nm and a lifetime of the 4I13/2 metastabile state of 7.2 ms were measured. Upon cw excitation at 978 nm, an increase of the 1.53 μm luminescence intensity larger than two-fold was detected in the Yb3+/Er3+-codoped waveguide with respect to the waveguide doped only with Er3+.