Compact Optical Switch Using the Tunability of a Au-Coated Hollow Core Waveguide

We design and fabricate a directional coupler type compact optical switch using the large variable characteristics of a hollow optical waveguide and use numerical simulations and experimentations to investigate the optical characteristics of the proposed directional coupler-type hollow waveguide optical switch. The optical switching operation is achieved by the optical power mode field distribution change and the coupling length in the directional coupler waveguide region because the air core thickness of the hollow waveguide is mechanically controlled by the electrical signal. The designed three-dimensional (3-D) optical hollow waveguide consists of a Au-coated reflector. The numerical simulation results show the possibility of a compact optical switch with a switch length of 1 mm when the air core thickness of the hollow optical waveguide is changed by 2 µm. The experimental device was a microstructured hollow optical waveguide coated with a thin Au film on a GaAs substrate using the same parameters as there used in the modeling. The experiment revealed a switching length of 0.9 mm and an extinction ratio of about 19 dB with a small change of air core thickness.