Optical Waveguide End Roughness in Correlation to Optical Coupling

With the ever-increasing demand for board-to-board optical data communications, the correlation between waveguide surface end roughness and coupling losses must be thoroughly investigated. This study measures end roughness of siloxane polymer optical waveguides in terms of optical coupling losses. Siloxane Polymers from Dow Corning were used to fabricate 50 x 50 mu m rectangular waveguides through photolithographic processes. Edge roughness was controlled through various grades of fiber-optic polishing films and then measured using interferometric microscopy (IFM). Controlled lab results are compared with industrial polishing techniques that are consistent with mass-production methods. Electromagnetic modeling revealed correlations between experimental and theoretical results.