Optical and structural properties of Er3+-doped P2O5–SiO2 and Al203–SiO2 planar waveguides

Er3+-doped P2O5–SiO2 planar waveguides, fabricated by flame hydrolysis deposition, are shown to have a higher gain than Er3+-doped Al2O3–SiO2 planar waveguides, fabricated by plasma enhanced chemical vapor deposition. An optical absorption measurement reveals that the high gain of Er3+-doped P2O5–SiO2 waveguides is due to a high population inversion. These optical properties are related to the homogeneity of the waveguide-core glasses which were analyzed with a scanning electron microscope.