Detachable Optical Chiplet Connector for Co-Packaged Photonics

Abstract

A key barrier to mainstream adoption of co-package photonics is a high-yielding and scalable assembly process. The current industry state-of-the-art for edge coupling is to attach fibers directly onto V-grooves etched into the silicon. With no ability for rework, any errors in this process will lead to loss of the entire package along with the expensive silicon committed to it. This problem is exacerbated by the yield compounding effect as the number of photonic chips on a package increases. In this paper, we discuss a novel approach to overcome this limitation. Our solution relies on a glass optical bridge with integrated waveguides and connector mechanical alignment features that can be attached to the photonics silicon at die level to produce a photonics module. The bridge attach can take place using existing V-grooves or alternate registration features in the silicon for alignment. Each photonic module is then tested to ensure it is known-good prior to committing it to the package, and overall yield is no longer compounded by the number of photonic modules on the package. Other benefits of this approach are the elimination of fiber pigtails which simplifies material handling in the manufacturing flow, and results in a fully detachable solution where the low-reliability fibers are no longer permanently attached to the expensive silicon. Low loss coupling was demonstrated using an optical bridge, with average losses from fiber into PIC of 1.41 dB. Average detachable connector losses of 0.33 dB were demonstrated along with integration into a photonic-electronic co-packaged assembly.