Measurement of planar waveguide losses using a coherent fiber bundle

We report on a nondestructive and accurate method for measuring the mode propagation losses of planar waveguides. A coherent optical fiber bundle images the scattered light streak at a remote detector plane. Measurements have been made over a wide range from low loss (≤1 dB/cm) to high loss (≥20 dB/cm) with a spatial resolution of 0.2 mm and a repeatability of 2%. Waveguides prepared by thermal evaporation, ion-exchange, and sputtering were characterized.