Switching the Optical Chirality in Magneto-plasmonic Metasurfaces Using Applied Magnetic Fields

TL;DR

This paper demonstrates the active control of optical chirality in magneto-plasmonic metasurfaces using magnetic fields, achieving significant modulation of circular dichroism at visible wavelengths, enabling advanced polarization nanophotonics.

Contribution

It introduces a novel magneto-optical metasurface with Ce:YIG that allows giant, continuous modulation of optical chirality via magnetic fields, advancing active chiral nanophotonics.

Findings

Achieved a circular dichroism modulation from -0.65° to +1.9° at 950 nm.

Demonstrated magnetic field tunable chiral imaging in large-scale metasurfaces.

Utilized low-loss, strong magneto-optical Ce:YIG for effective chirality control.

Abstract

Chiral nanophotonic devices are promising candidates for chiral molecules sensing, polarization diverse nanophotonics and display technologies. Active chiral nanophotonic devices, where the optical chirality can be controlled by an external stimulus has triggered great research interest. However, efficient modulation of the optical chirality has been challenging. Here, we demonstrate switching of the extrinsic chirality by applied magnetic fields in a magneto-plasmonic metasurface device based on a magneto-optical oxide material, Ce1Y2Fe5O12 (Ce:YIG). Thanks to the low optical loss and strong magneto-optical effect of Ce:YIG, we experimentally demonstrated a giant and continuous far-field circular dichroism (CD) modulation by applied magnetic fields from -0.65{\deg} to +1.9{\deg} at 950 nm wavelength under glancing incident conditions. The far field CD modulation is due to both magneto-optical circular dichroism and near-field modulation of the superchiral fields by applied magnetic fields. Finally, we demonstrate magnetic field tunable chiral imaging in millimeter-scale magneto-plasmonic metasurfaces fabricated using self-assembly. Our results provide a new way for achieving planar integrated, large-scale and active chiral metasurfaces for polarization diverse nanophotonics.