A Novel Technique to Measure the Propagation Loss of Integrated Optical Waveguides

A novel method is presented to measure the propagation loss of integrated optical waveguides. The measurement system involves two 3-dB couplers, a charge coupled device camera, and a signal processing unit. The propagation loss measured from this technique is found to be independent of coupling conditions. The propagation properties of low to high loss waveguides prepared by annealed proton exchange (APE) in lithium niobate $(LiNbO_3)$ and silver ion exchange in BK7 glass substrates are examined. The measurement system is found to be feasible over a broad range. This method offers a precision of 0.04 dB in case of a 25-mm-long waveguide prepared by APE