Determining waveguide coupling efficiency by observing reflected light from the end face

The amount of light coupled into a waveguide depends on end-face irregularities. We have developed a technique to assess the light coupling performance of waveguides by measuring their back reflected light characteristics. The reflected light can be separated into two parts, the specular and the diffuse reflected light. The amount of each gives us information on how well light can be coupled into a waveguide. This technique is especially useful in integrated optics made of polymer materials where end face quality is a strong function of the material preparation technique and processing