An improved technique for measuring optical loss in slab waveguides

A technique has been developed to measure optical losses in slab waveguides. The technique relies on coupling light with a prism into a film coated on a substrate. The total transmitted light at the end of the cleaved substrate is measured with a photodetector as a function of the distance from the prism coupler. This technique is useful for low loss and low scattering films and is accurate to +/- 0.15 dB/cm.