A New Approach of Hetero-Cladding for Design of Compact Si Photonic Directional Coupler

In this letter, we propose a new approach of hetero-cladding for realization of compact CMOS compatible silicon photonic directional couplers. The proposed hetero-cladding comprises ferroelectric BaTiO₃ (BTO) and SiO₂ to control the evanescent mode within the structure. The results show very small and identical coupling length for both TE and TM modes with reduced device cross-section, which promises for a huge reduction in the footprint of both conventional and programmable photonic integrated circuits. The concept can also be utilized to design compact, low loss and energy efficient phase shifters, other types of couplers, sensors etc.