Design and Fabrication of Directional Coupler Type Hollow Waveguide Optical Switch with Variable Air Core

We present a device design and fabrication of a novel hollow-waveguide optical switch consisting of a directional coupler with variable air cores. The numerical simulation and experimental characterization of the proposed optical switch performance is discussed. Switching operation is achieved by mode-field change and coupling beat length in the directional coupler section, as the air core thickness is adjusted mechanically. Our modeling results show a possibility of a compact optical switch with a sub-mm switch length. A proof-of-concept experimental device is fabricated with microstructured Aumirror waveguide on GaAs substrates. We observed optical switching extinction of about 17 dB with a switching length of 0.9 mm and a small change of an air core thickness.