Er-doped oxyfluoride silicate thin films prepared by pulsed laser deposition

Er-doped oxyfluoride silicate thin films were deposited using pulsed laser deposition. The target glass composition was 65SiO2- 3Al2O3-12Na2O-10PbF3-10LaF3 (in mol%) + 1Er2O3 (in wt.%). Irradiations were performed using an ArF excimer laser in a dynamic flow of oxygen of pressure 5 Pa. The laser fluence at the target surface was 2 J/cm2. Films were deposited on pure silica substrates, either at room temperature or on a substrate-holder heated at 200 °C. The optical transmission of the films in the NIR-visible-UV regions (200-2500 nm) was recorded using a double beam spectrophotometer and was higher than 90%. The optical spectra were analyzed using computer code to evaluate the refraction index (n), the extinction coefficient (k) along with the film thickness. The films deposited at room temperature were cracked whilst examined under scanning electron microscopy and reactive ion etching. By comparison, the films deposited at 200 °C remained undamaged. Optical waveguides were written on the films deposited at 200 °C using dry reactive ion etching with attenuation in the range of 0.74 dB/cm at 633 nm, measured using a prism coupler.