A study of the preparation and properties of copper-containing optical planar glass waveguides

We have studied the fabrication and properties of the Cu+-containing waveguides. These waveguides were fabricated in a special soda-lime silicate glass as well as in commercial optical glass substrates, by using an ion exchange in the melts containing either Cu+ or Cu2+, at temperatures from 350°C to 500°C, and for periods from 5 min to 21 h. The optical properties of the fabricated waveguides were characterized using both mode and photoluminescence spectroscopy. The composition of waveguiding layers was studied using Rutherford Backscattering Spectrometry (RBS) and ESCA. The presence of divalent copper was determined using Electron Paramagnetic Resonance (EPR). After ion exchange, the refractive index increased, depending on the fabrication conditions, up to Δn=+0.0693, and the waveguides supported up to 16 TE and TM modes. The depths of the fabricated waveguides varied between 6.0 and 27.5 μm. The most intensive blue-green luminescence was achieved with the samples that were ion-exchanged in the Cu2Cl2·ZnCl2 melt, where the presence of Zn2+ strongly impeded the oxidation of Cu+ to Cu2+. Both oxidation states of copper (Cu+ as well as Cu2+) were found in the waveguides fabricated in the pure Cu2Cl2. The main advantage of the copper-containing waveguides is the possibility of integrating the passive and active functions of the waveguides on the same substrate.