Chirality and directional emission of a SiNx-based microring resonator with position controllable scatters

Chiral device breaking time-reversal symmetry can control the propagation direction of the light which is great significant for the information processing on chip. Here we report a new chiral structure based on silicon nitride (SiN _x ) microring resonator embedded with a scatterer in the evanescent region the waveguide. The simulation results show that the asymmetry backscattering of the whispering-gallery modes (WGMs) can be induced by a single scatterer and thus directional transmission observed. In addition, the dimensions and relative position of the scatterer have been optimized to obtain the strongest chirality effect, resulting in an extinction ratio of up to 10 dB. Our results open pathways towards many chiral integrated nanophotonic devices.