OPTICAL LOSSES IN SOL-GEL DERIVED LEAD LANTHANUM TITANATE WAVE-GUIDES

A series of solgel derived lead lanthanum titanate films were prepared on Coming 7059 glass substrates. Waveguiding properties of these film s were studied as a function of La content and film thickness. 0.5M pr ecursor solutions based on lead acetate, La nitrate and Ti/Zr alkoxide s were refluxed for 1 hour and later spincoated at various speeds on t he substrates under clean room condition. Films were fired to 400C for 1 hr to burn off the organics and to consolidate the coatings. They w ere then fired at temperatures ranging from 500C to 600C. XRD was used to determine the phase assembly present in these films: the presence of La seemed to aid in the formation of the perovskite phase. Transmis sion spectra were gathered using a UV-Vis spectrometer; and the spectr a were then used to calculate the refractive indices based on the enve lope method. The waveguiding properties and optical attenuation were s tudied via prism coupling using a rutile prism. The optical losses in these films decrease with La content and also in thicker single-coated films. On the other hand, thicker films achieved by multiple coating appeared to exhibit higher losses. Crystalline PLZT 28/0/100 yielded l oss of < 2 dB/cm, the lowest among reported literature values for any sol-gel or sputtered PLZT films.