Connection characteristics of silicon nanowire waveguides and fabrication of physical contact switches

Optical characteristics of silicon nanowire waveguide connections are studied both theoretically and experimentally. Effects of geometrical sizes and positional alignments on optical performance are investigated. Results show that waveguide connections with tips wider than 500 nm and tip angles greater than critical angle enable high transmittance and less sensitivity to positional misalignments. Connection with 1.5 μm-wide tip at 74° tip angle is experimentally found to yield 96.3% transmittance at 200 nm offset distance. 1x2 mechanical switch using the aforementioned silicon nanowire waveguide geometry is designed and fabricated. Studied results are useful for realizing low-loss microelectromechanically-actuated connections in silicon subwavelength integrated optical circuits in the telecommunication field.