Fluorescence in ion exchanged BK7 glass slab waveguides and its use for scattering free loss measurements

We investigated the fluorescence in Na + →Ag + -ion exchanged BK7 glass slab waveguides. The waveguide characteristics, the refractive index profile and the losses were measured. The index profile could be described by a nonlinear diffusion equation. The fluorescence, due to colloidal silver particles, increases with increasing ion exchange time and with decreasing wavelength of the guided light. In addition, the waveguide surface was plasma treated by ion glow discharge and an enhancement of fluorescence was observed with increasing discharge time. Most of the fluorescence light does not couple into waveguide modes and can therefore be used to measure the losses surface scattering free.