Design and Fabrication of Multi-Mode Interference Hollow Waveguide Optical Switch with Variable Air Core

Abstract

We present the design and fabrication of a novel hollow waveguide optical switch composed of a multi-mode interference (MMI) coupler with a variable air core. The numerical simulation and measurement of the proposed optical switch is carried out for investigating switch performances. Switching operation can be obtained by mechanical displacement of the air core of an MMI hollow waveguide. The switching operation is based on the variation of the mode-field associated with the mechanical displacement. Our modeling shows a possibility of a compact optical switch with a sub-mm switching length. We fabricated an MMI hollow waveguide optical switch consisting of Au mirrors deposited on two GaAs substrates. One of the substrates is mechanically moved, resulting in the change of the beat length of the MMI waveguide. We observed optical switching of about 85% optical power fraction with a switch length of 1.1 mm and small displacement of an air core thickness.