Abstract

As one of the important photonic integrated platforms, microring resonators based on silicon nitride have great potentials in photonic applications such as filters, sensors, modulators, as well as microcombs generation. They are usually designed with a multi-mode waveguide to guarantee lower loss and desirable dispersion properties. To improve device performance such as quality factor (Q) and extinction ration (ER), the coupling region should be design carefully for restraining the unwanted excess coupling loss induced by the low-Q higher order modes and enhancing the power coupling to high-Q fundamental modes. Coupling ideality investigation is a useful tool to evaluate the coupling loss induced from modal coupling intuitively, which is defined as the ratio of power coupled to the targeted modes divided by the total power coupled to all modes [1, 2].

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