Study of erbium doped ZrO2 waveguides elaborated by a sol-gel process

Er3+ doped ZrO2 thin films (1 mol%) are prepared by sol-gel process and dip -coating technique. After annealing the films exhibit good optical quality and waveguiding properties. The observed fluorescence of Er3+ ions, especia lly at 1.53 mu m, is used by Waveguide Fluorescence Spectroscopy (WFS). It is shown that the band shape of the I-4(13/2) --> I-4(15/2) transition depe nds on the annealing temperature. Waveguide Raman Spectroscopy (WRS) is use d at room temperature in order to analyse the films structure. Such study w as conducted for different annealing temperatures at an excitation waveleng th where erbium absorption is low (i.e. 676.4 nm). An amorphous waveguide i s obtained below 400 degrees C. Up to 800 degrees C, the tetragonal phase m ainly appears, although both monoclinic and tetragonal phases are simultane ously detected in undoped waveguides at this temperature. High Resolution T ransmission Electron Microscopy (HRTEM) observations provide the mean diame ter of ZrO2 crystallites which increases up to 15 nm after a 800 degrees C heat-treatment. This large size explains in part the high attenuation measu red on this film at 676.4 nm (around 20 dB/cm). (C) 1999 Elsevier Science B .V. All rights reserved.