Copper Doped Waveguides in Glass Substrates

Abstract

We have studied the fabrication and properties of the copper ion exchanged waveguides that were fabricated in special Na 2 O-rich soda-lime silicate glasses and in commercial BK7 optical glass substrates. The ion exchange was performed in melts containing either Cu I or Cu II at temperatures from 350°C to 500°C for times ranging from 5 min to 21 h. Optical properties of the fabricated waveguides were studied using mode spectroscopy and photoluminescence spectroscopy, and composition of the waveguides was determined by using Scanning Electron Microscope (SEM), Rutherford Backscattering Spectrometry (RBS), Electron Paramagnetic Resonance (EPR), and Electron Spectroscopy for Chemical Analysis (ESCA). After the ion exchange the refractive index increased, according to fabrication conditions, up to j n = +0.0693, and the guides supported up to 16 TE and TM modes. The Cu I 5 Cu II redox reaction during the fabrication depended strongly on the composition as well as the temperature of the reaction melts. In the Cu 2 Cl 2 :ZnCl 2 melts, the oxidation of Cu I to Cu II was strongly impeded, so that Cu I prevailed in the waveguiding region. These samples exhibited the most intensive blue-green luminescence in spite of those fabricated by using the Cu II -based reaction melts, where practically no blue-green luminescence was observed. ESCA measurement revealed an easy charge transfer between both oxidation states of copper in the very surface regions of the samples.