Microlens Coupler from Integrated Photonic Circuit to Fiber Design for Space Application

This study presents a novel design for a microlens coupler to transfer light from a straight waveguide to a single-mode fiber (SMF). Our design combines improved mode matching and enhanced alignment tolerance compared to edge coupling. An investigation of the alignment tolerance is done by assessing coupling efficiency under various degrees of manufacturing-induced misalignment. Singlet and diffractive lenses are incorporated into our design to focus the light into the fiber precisely. Comprehensive simulations demonstrate that the diffractive lens outperforms edge coupling and singlet lens in coupling efficiency. Fabrication methods such as additive manufacturing are discussed for future works. Our findings underscore the potential of innovative microlens coupler design in advancing free space optical communication (FSOC) systems.