Non‐Reciprocity in High‐Q Ferromagnetic Microspheres via Photonic Spin–Orbit Coupling

Abstract

AbstractNon‐reciprocal devices serving as fundamental elements in photonic and microwave circuits have attracted great attention for its applications in both classical and quantum information processing. The spin–orbit coupling (SOC) of light in microstructures shows that the polarization affects and controls the spatial degrees of freedom of light, which could been exploited to break the reciprocity of light transmission. Here, non‐reciprocal light transmission is demonstrated experimentally in high‐quality factor yttrium iron garnet microspheres via photonic SOC and Faraday effect. By applying an magnetic field in the vertical direction of resonator equator, the degeneracy of the clockwise and counter‐clockwise whispering gallery modes are lifted. The non‐reciprocal effect is shown for both polarizations and promises applications including non‐reciprocal photonic devices, magneto‐optic modulators, and magnetometers.