Innovative Photocurable Resin-Based Cylindrical Microlens Fiber for Silicon Photonics Coupling

High coupling efficiency with passive alignment of cylindrical microlens fiber fabricated by photocurable resin with simple process to achieve desired lens structure is presented. Optimal lens dimensions of 4-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m upper base, 9-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m lower base, and 12-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m height were determined by simulation software. Despite mode conversion losses, maximum coupling efficiency reached 71.2%. Experimental results closely matched simulations of 67.6% coupling efficiency. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5~\mu $ </tex-math></inline-formula>m offset in the X-Y plane, defined within a Cartesian coordinate system, resulted in a measured 3-dB efficiency drop. Compared to microlens fiber with grinding processes, the microlens fibers offer improved efficiency and tolerance. The proposed microlens fibers with array setups could reduce alignment time and cost during packaging, suggesting applications in silicon light modules, optical radar, and biomedical measurements.