Excimer laser ablating preparation of Ba2NaNb5O15 optical waveguiding films on (001) KTiOP04 substrates

Ba2NaNb5O15 (BNN) films on (001)-oriented KTiOPO4 (KTP) substrates were prepared by excimer laser ablation. Characterization of the films by the X-ray diffraction and scanning electron microscopy revealed that the films as prepared at 700°C and then cooled rapidly were (100) oriented, and a low density of micro twined substructures appeared in the films. As the films were annealed at 700°C and then cooled slowly through the ferro-elastic transition point (222)-oriented twined substructures in the films were identified. Besides the dominant set of waveguiding multimodes, a new set of m-lines which are attributed to the micro-twined substructures were observed. Favorable waveguiding property of the films were demonstrated by measurement of the optical propagating loss lower than 1.0dB/cm.