Low loss, polarization-independent, large bandwidth mode converter for edge coupling

摘要

A mode converter formed by parallel tapered waveguides on a SiN platform. The waveguides form a trident structure comprising a main waveguide with an inverse taper structure, and a pair of waveguides on each side of the main waveguide. Each adjacent waveguide has a taper structure but one that is opposed to that of the main waveguide, namely, a width that gradually increases along the direction of light propagation to a larger value at an end tip thereof. The end tips of the waveguides terminate along a common input/output facet of the converter. The adjacent waveguides help to shape the mode of the light propagating through the main waveguide, in so doing enabling the converter to exhibit high coupling efficiency and polarization independence in the full optical communication bands (i.e., from O to L-band) by successfully tuning the mode shape at a chip facet. The trident mode converter enables efficient optical fiber-to-chip coupling.