Preparation and infrared emission of silica–zirconia–alumina doped with erbium for planar waveguide

Abstract

The sol–gel synthesis of Er 3+ (1–5%) doped silica(83)–zirconia(17) waveguide materials with addition of aluminum (6–20 at%) giving a FWHM ( 4I 13/2– 4I 15/2)>60 nm is reported. Zirconia with high refractive index of 1.9 and low phonon energy is a good material compared with titania. The films were deposited on silicon or silica substrate by dipcoating technique using the precursors of Si(OC 2H 5) 4 (Aldrich), Zr(C 3H 7O) 4, CH 3–CH(OH)–CH 3, C 5H 8O 2 , Al(NO 3) 3·9H 2O, Er(NO 3) 3·5H 2O and Yb(NO 3) 3·5H 2O (Merck). The dipcoating rate of 2 and 3 mm/s were controlled by computer. Samples were calcinated at temperatures from 70 to 900 °C. The optical properties were studied by photoluminescent spectra and decay time. Influence of the Al 3+ concentration and the heat treatment conditions for the Er 3+ luminescent properties were studied. An energy transfer from 2F 5/2 (Yb 3+) to 4I 11/2 (Er 3+) multiplets is followed by a relaxation to the 4I 13/2 (Er 3+) and an efficiency luminescence of Er 3+ ( 4I 13/2– 4I 15/2) was clearly measured. It is interesting to indicate that the lifetime of few ms of Er 3+ at 1530 nm in the sample Si(83)Zr(17)Al(6%)Er(1%)Yb(1%) is longer than for the sample without Yb ions. Multilayer thin films were prepared. The thickness, refractive index, the roughness about 2 nm and a propagation loss<2.5 dB/cm were studied for active planar waveguide applications.