Electro-optical modulator using silicon on insulator Michelson interferometer with electro-optical polymer

Abstract

Electro-optical modulator is a key component in data-communication, telecommunication and optical interconnects. In this paper we propose a novel electro-optical modulator design that utilizes Michelson Interferometer based on the widespread Silicon-on-insulator (SOI) technology with 220nm thickness of the silicon device layer. The proposed modulator is working at the telecommunication wavelength 1550nm. Due to its high Pockels coefficient and CMOS compatibility electro-optical polymer (EOP) is used as an active material where its refractive index changes with the applied electric field. The Michelson Interferometer consist of directional couplers which are used in splitting and combining the input power to and from the interferometer arms with 50/50 ratio at 1550nm. Slot waveguide with EOP clad is used in the interferometer arms to achieve high optical field confinement in the EOP which maximizes the mode effective index change of the interferometer arms when applying voltage. Finite Difference Eigen mode (FDE) solver was used to calculate the mode field profiles, effective index and loss of the slot waveguide. By optimizing the waveguide dimensions, we have achieved a waveguide sensitivity Swg=dneff/dnEOP of 0.9135 at 1550nm. Three-dimensional finite-difference-time-domain (3D-FDTD) method was used in the analysis and optimization of our Michelson Interferometer electro-optical modulator. Results show that our Michelson Interferometer modulator exhibit lower VπLπ product than previously published SOI based modulators. Moreover, the modulator exhibit low insertion loss (IL) leading to high extinction ratio (ER) in addition to its CMOS compatibility. Thus, our proposed modulator allows for compact, high performance and low cost modulators.