The attenuation of multimode-strip-waveguides produced by silver-sodium ion exchange in glass was determined by measurement of the insertion losses of the waveguide and calculation of coupling losses between a graded index fibre and the waveguide. For the theoretical determination of coupling losses a new model for calculation was developed. This so called method of local coupling effectivities provides an excellent agreement between theoretical and experimental coupling losses. On the basis of our measuring process an accuracy of 0.2 dB could be achieved for the determination of waveguide attenuation.
"Attenuation Measurement Of Strip-Waveguides", Proc. SPIE 1085, Optical Fibres and Their Applications V, (30 January 1990); doi: 10.1117/12.952978; https://doi.org/10.1117/12.952978