Design and Optimizing Backside Grating Couplers in Si-Photonics Circuits

Grating couplers are essential in photonic systems, facilitating efficient light coupling between optical fibers and on-chip waveguides and allowing for wafer-level testing. With the increasing integration of photonics in communication systems like the internet, there is a growing need for grating couplers to be utilized on the backside of the chip, in addition to the top side. This paper presents a novel design for backside grating couplers by optimizing Si overlay on conventional grating couplers on silicon photonics circuits. The designed backside grating coupler simulation shows the coupling efficiency from the waveguide toward the back side is around 90% with reflection less than 2 %.