Yellow-to-violet up-conversion luminescence in neodymium-doped sol-gel GeO ₂ γ-glycidoxypropyltrimethoxysilane hybrid planar waveguides

Neodymium-doped Ge O2 γ -glycidoxypropyltrimethoxysilane hybrid planar waveguide films were prepared by a low-temperature sol-gel technique from an organic-inorganic hybrid system for photonic applications. Optical properties such as refractive index, thickness, propagation modes, and attenuation coefficient of the hybrid planar waveguides were investigated by using a prism coupling technique. An intense room-temperature yellow-to-violet up-conversion emission at 397 nm (D 32 4 → I 132 4) was measured from the hybrid planar waveguide film heated at a low temperature of 100 °C upon excitation with a xenon lamp at the wavelength of 580 nm. In addition to this intense violet emission, a relatively weak ultraviolet emission at 376 nm and a blue emission at 468 nm were also observed. The mechanism of the up-conversion emission is proposed, and they indicate that the excited-state absorption process originating from the long-lived F 32 4 excited state should be responsible for the up-conversion process.