Low-Cost Interfacing of Fibers to Nanophotonic Waveguides: Design for Fabrication and Assembly Tolerances

The high cost and low scalability of interfacing standard optical fibers to nanophotonic waveguides hinder the deployment of silicon photonics. We propose a mechanically compliant low-cost interface with integrated polymer waveguides. Our concept promises better mechanical reliability than a direct fiber-to-chip coupling and a dramatically larger bandwidth than diffractive couplers. Our computations show a 0.1-dB penalty over a 200-nm bandwidth, whereas typical two-polarization vertical couplers show a similar to 1-dB penalty over a 30-nm bandwidth. In this paper, we present a comprehensive analysis of the design space using optimization routines to achieve a fabrication-and assembly-tolerant design. We demonstrate the concept feasibility through extensive tolerance analysis with parameter control assumptions derived from low-cost manufacturing.