A proton-implanted planar waveguide fabricated in terbium gallium garnet crystal

The investigation on the terbium gallium garnet (TGG) crystal waveguides in the visible and near-infrared bands is significant for potential applications in science and technology. In this work, we report on a TGG planar waveguide based on the proton irradiation with an energy of 400 keV and a dose of 8 x 10(16) ions/cm(2) . The annealing treatments are adopted to improve optical performances of the waveguide on the conditions of 260 degrees C and 410 degrees C severally for 1 h. The dark-mode spectra and the refractive index distributions of the TGG waveguide are obtained before and after the thermal treatments. There is a strange phenomenon that nine modes are observed on the m-line curve after the annealing treatment at 410 degrees C. The theoretical and experimental results demonstrate that the fabricated waveguide annealed at the temperature of 410 degrees C can propagate more guided modes and have better capacity to confine light.