Mach--Zehnder Interferometer Based on Coupled Dielectric Pillars

We propose a Mach--Zehnder interferometer (MZI) based on coupled dielectric pillars. It is composed of single-row pillar coupled waveguide modulating arms and three-row pillar waveguide 3dB couplers. The slow light property and transmission loss of the single-row pillar modulating arm are optimized by the plane wave expansion method. A short 3dB coupler is designed based on the modes transformation in three-row pillar waveguide. Finite difference time domain simulations prove the validity of this MZI and show that it has low insertion loss of <1.1dB and high extinction ratio of >12dB.