Optical properties of Bi2.25La0.75TiNbO9 thin films grown on fused silica substrates by PLD

Layered-perovskite ferroelectric Bi2.25La0.75TiNbO9 (LBTN-0.75) optical waveguiding thin films have been prepared on fused silica substrates by pulsed laser deposition (PLD). X-ray θ–2θ scans revealed that the films are single-phase perovskite. The optical properties, such as the wavelength dependence of the transmittance and the refractive index, were determined. The average transmittance of the film is 75% in the wavelength range of 200–1100 nm and the band gap Eg = 3.46 eV. The optical waveguiding properties of the films were characterized by using prism coupling method. The distinct m-lines of the guided transverse electric (TE) and transverse magnetic (TM) modes of the LBTN-0.75 films waveguide have been observed. The film homogeneity and the film–substrate interface were analyzed using the inverse Wentzel–Kramer–Brillouin (iWKB) method.