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.

Abstract— The present work proposes a new approach of hetero-cladding for silicon photonic directional couplers and outlines its contributions towards realization of a compact, tunable and energy efficient directional coupler. 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 (PICs). The proposed concept could also be utilized to design compact, low loss and energy efficient phase shifters and other types of couplers.