American Chemical Society
ph1c01561_si_001.pdf (1.76 MB)

Pseudospin–Orbit Coupling for Chiral Light Routings in Gauge-Flux-Biased Coupled Microring Resonators

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journal contribution
posted on 2022-01-19, 15:36 authored by Chengzhi Qin, Andrea Alù, Zi Jing Wong
Pseudospin–orbit coupling of light, exploiting artificially defined photon spins to steer its spatial motion, underlies many intriguing light–matter interaction phenomena and spin-based optical devices. Microring resonators, hosting counter-circulating whispering gallery modes as two pseudospins, are promising candidates for spin-based light control. Here, by applying a gauge-flux biasing in a microring resonator array with different boundary topologies, we establish a new pseudospin–orbit coupling framework and achieve spin-locked chiral light routing effects. We show that for a closed-loop array with Born–von Karman periodic boundary conditions, a real gauge-flux biasing can induce opposite dispersion relation shifting and hence clockwise and counterclockwise light routings for the two pseudospin modes. We attain spin-locked opposite routing paths both for single-port and multiport inputs using resonator trimer and quadrumer structures, respectively. For open boundary conditions, we find that an imaginary gauge-flux biasing can squeeze the two pseudospin modes to the opposite ports, showing the “non-Hermitian skin effect” and spin-locked amplified and decayed routing effects. Our study may find applications in spin-resolved networks-on-chip optical communications, interconnections, and signal processing.