Optical waveguide losses of PZT thin films with various Zr/Ti stoichiometries

Sol-gel derived PZT thin films were spincoated on Corning 7059 glass substrates and fired to temperatures ranging from 500C to 600C for 30 min. The PZT compositions consisted of PZT x/y where x/y = 0/100, 20/80, 35/65, 53/47, 65/35, 80/20 and 100/0. Only single coated films were used since multiple coatings led to higher losses. XRD was used to characterize the phase assembly of the fired films and indicated that films with higher Zr contents contained proportionally more pyrochlore; while films with higher Ti contents have higher perovskite contents. UV-VIS spectroscopy was utilized to obtain the transmission and optical properties(refractive index and extinction coefficient) via the envelope method. Waveguide losses were measured using prism coupling at the 633 nm HeNe laser wavelength. The waveguide losses in the PZT films ranged from 1. 3 to 2. 0 dB/cm. The surface texture or morphology of the films significantly affected the optical losses as striated films gave losses of 2. 7 to 3. 3 dB/cm. The relatively low losses of the PZT films, together with their high values of refractive indices (2. 1 to 2. 7) make them highly attractive as waveguides in integrated optics.