Losses in NLO polymer integrated optic channel waveguide devices

摘要

Abstract: Characterizing propagation losses in integrated optical structures is quite cumbersome and time consuming. Particularly for single-mode optical polymer channel waveguide devices that are butt-coupled, uncertainty of end facet preparation can add considerable error in estimated propagation losses. At COMSAT Laboratories, we have produced NLO polymer channel waveguides of buried and stripe designs by reactive ion etching and evaluated their loss performance by cutback and retro-reflection techniques. The first method, which is based on optical transmission in polished butt-coupled devices, is commonly used. The second method requires retro-reflection of the transmitted beam so that the input light beam (retro-reflected) is matched to the optical waveguide beam profile. This method has a higher accuracy because there is no need to correct for the mode-mismatch loss typical of the first method. Also, loss measured at different wavelengths can be used to distinguish true propagation and scattering losses contributed by structural imperfections in the channel waveguide sidewalls. !6