Investigation on optical properties of Bi_(2.85)La_(0.15)TiNbO_9 thin films by prism coupling technique

摘要

Layered-perovskite ferroelectric Bi_(2.85)La_(0.15) TiNbO_9 (LBTN) optical waveguiding thin films were grown on fused silica substrates by pulsed laser deposition (PLD). X-ray diffraction (XRD) revealed that the film is highly (00l) textured. We observed sharp and distinct transverse electric (TE) and transverse magnetic (TM) multimodes and measured the refractive indices of LBTN thin films at 632.8 nm. The ordinary and extraordinary refractive indices were calculated to be n_(TE) = 2.358 and n_(TM) = 2.464, respectively. The film homogeneity and the film-substrate interface were analyzed using an improved version of the inverse Wentzel-Kramer-Brillouin (iWKB) method. The refractive index of the film remains constant at n_0 within the waveguiding layer. The average transmittance of the film is 70% in the wavelength range of 400-1400 nm and the optical waveguiding properties were evaluated by the optical prism coupling method. Our results showed that the LBTN films are very good electro-optical active material.