Optical properties of rare earth ion (Nd3+, Er3+ and Tb3+)-doped alumina films prepared by the sol–gel method

Abstract Rare earth ion (Nd3+, Er3+ and Tb3+)-doped alumina films were prepared by the sol–gel method using aqueous alumina sol. The effects of dopant concentration and treatment temperature on the optical properties, absorption and emission were examined for the doped films. Alumina films prepared by this method gave a high dopant concentration (0–15 mol% per alumina). Significant concentration quenching did not occur in this concentration range. The emissions from 5D3 and 5D4 of Tb3+-doped film reflected sensitively a matrix environment around Tb3+ ions. Er3+- and Nd3+-doped alumina films resonantly excited by cw Ti–sapphire laser (800 nm) showed upconversion emission at room temperature. The former gave 548 nm ( 4 S 3/2 → 4 I 15/2 ) and 640 nm ( 4 F 9/2 → 4 I 11/2 ) signals, and the latter 640 nm ( 4 G 7/2 → 4 I 11/2 ), which were dependent on alumina.