Double inverse nanotapers for efficient light coupling to integrated photonic devices

Abstract

Efficient light coupling to integrated photonic devices is of key importance to a wide variety of applications. “Inverse nanotapers” are widely used, in which the waveguide width is reduced to match an incident mode. Here, we demonstrate novel “double inverse” tapers, in which we reduce both the waveguide height and width. We demonstrate $>45\%$ chip-through coupling efficiency for both the transverse electric and transverse magnetic polarizations in ${\mathrm{Si}}_3{\mathrm{N}}_4$ tapers of $>500\mathrm{nm}$ width, in comparison to regular inverse tapers that necessitate $<100\mathrm{nm}$ width. The double inverse tapers show polarization-independent coupling and allow the fabrication using photolithography, relevant for applications at near-infrared and visible wavelengths, e.g., supercontinuum and soliton microcomb generation.

© 2018 Optical Society of America

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