Vertical assisted directional-coupler from Silicon-on-Insulator to Silicon Nitride platforms

Silicon (Si) and Silicon Nitride (Si3N4) are two leading materials for the creation of photonic integrated circuits (PICs). The necessity of efficiently couple light between Si[1]and Si3N4-PICs is becoming more relevant to face crucial applications in various technologic sectors, as high bandwidth optical interconnects and mid-infrared and visible optical sensing. However, the strong refractive index mismatch between Si and Si3N4 leads to challenging coupling between the elements used to carry the light throughout the PIC waveguides (WGs). We propose a solution based on vertical assisted directional-couplers allowing a computational Coupling-Efficiency (CE) up to 82%.