Efficient Fiber‐to‐Chip Interface via an Intermediated CdS Nanowire

Abstract

AbstractAn efficient fiber‐to‐chip interface via an intermediated CdS nanowire is demonstrated. The fiber mode is firstly squeezed through a fiber taper drawn at the end of a single‐mode fiber, then evanescently coupled into an intermediated CdS nanowire with a longitudinally tapering profile, and finally coupled into an on‐chip silicon waveguide (SiW) via a waveguide taper fabricated on it. Since the fiber‐nanowire‐SiW cascade structure is designed to match effective indices in each coupling area, such a fiber‐to‐chip interface ensures a bidirectional coupling efficiency up to 90% and a 3‐dB bandwidth over 100 nm in experiments. The difference of coupling efficiencies between the TM or TE modes is less than 0.5 dB in the spectral range of 1545–1635 nm. The footprint of the on‐chip coupling structure is about 10 µm in size. The results may provide a compact, efficient, and versatile fiber‐to‐chip interface in applications including optical interconnects, coherent communication, and quantum optical circuitry.