Polymer tapered pillar grown directly from an SMF core enables high efficiency optical coupling with a silicon photonics chip

Silicon photonics technology has attracted considerable attention because of the growing need for high-bit-rate optical interconnections. The low coupling efficiency resulting from the difference in spot size between silicon photonic chips and single-mode fibers remains a challenging issue. This study demonstrated a new, to the best of our knowledge, fabrication method for a tapered-pillar coupling device using a UV-curable resin on a single-mode optical fiber (SMF) facet. The proposed method can fabricate tapered pillars by irradiating only the side of the SMF with UV light; therefore, high-precision alignment against the SMF core end face is automatically achieved. The fabricated tapered pillar with resin cladding has a spot size of 4.46 µm and a maximum coupling efficiency of -0.28 dB with a SiPh chip.