Switching the Optical Chirality in Magnetoplasmonic Metasurfaces Using Applied Magnetic Fields

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° to +1.9° 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 2 provide a new way for achieving planar integrated, large-scale and active chiral metasurfaces for polarization diverse nanophotonics. KEYWORDS: Magnetoplasmonic, Metasurface, Optical Chirality, Magneto-optical effectChirality describes the symmetry property of a structure, that its mirror image cannot be superimposed with itself through translation and rotation operations, like our two hands. The chirality of biomolecules is universal in our living body, such as amino acid and proteins, which has significance in biomolecules recognition. 1,2 However, the chiroptical signal of chiral biomolecules is very weak. Recently, chiral plasmonic 3,4 and all dielectric structures 5,6 with large chiroptical response have attracted great research interest. Benefitted from advanced nano-fabrication technologies, 3D or planar chiroptical nanostructures, such as helices, 7,8 shurikens, 9 gammadions, 6,10 and twisted split-rings 11 have been fabricated. On the other hand, extrinsic chirality can also be observed in achiral photonic nanostructures under obliquely incidence conditions. The extrinsic chirality is originated from asymmetric distributions of electromagnetic fields, i.e. the electromagnetic near field distribution is chiral. 12 Nanophotonic structures such as nanoholes, 12 squares 13 and split ring resonators 14,15 showed large extrinsic chirality. For instance, Ben et al.demonstrated a ~4 times stronger optical chirality in achiral periodic nanoholes compared to the gammadion structure. 12 Recently, Abraham et. al. experimentally demonstrated that the achiral nanohole structures can also show superchiral near-fields even at perpendicular incidence conditions. 16 In that case, the far-field circular dichroism (CD) background signals from the plasmonic structures is eliminated, improving the sensitivity for chiral molecule sensing applications. These reports demonstrate a promising potent...

A Multiple Chirality Switching Device for Spatial Light Modulators

“…Chirality switching is arousing great interest because of its great potential applications in optical communication, optical sensing, three-dimensional displays, and chiral bioimaging. [1] Inspired by incredible information communication of life systems, such as regulation of nucleic acid and recognition of suitable amino acids for proteins duplication, [2] a lot of artificial chiral-optical-switching materials (chiroptical switches), stimulated by light, [3] temperature, [4] redox additives, [5] electric-field (e-field), [6] pH (acid/base), [7] solvent, [8] and magnetic field [9] have been developed successfully. A few chiroptical switches based on electrochromic (EC) materials, whose optical properties can be changed reversibly by redox reactions under the stimulation of e-field, exhibit obvious advantages owing to their rich optical tunability and simple structures.…”

High‐Efficiency Terahertz Nonreciprocal One‐Way Transmission and Active Asymmetric Chiral Manipulation Based on Magnetoplasmon/Dielectric Metasurface

“…[17] By reasonably designing magneto-optical material into the artificial microstructure to form the magnetooptical photonic crystal, metasurface, and plasmonics, [18][19][20][21][22][23] the magneto-optical effect from the material itself can be significantly enhanced, and some new physical mechanisms can be observed, such as the enhanced Faraday rotation, nonreciprocal topological edge states, and photonic spin Hall effect. [24][25][26][27][28][29][30] The lack of low-loss and high-efficiency nonreciprocal isolators has become one of the limitations in the development of terahertz (THz) application systems. This work demonstrates that the longitudinally magnetized InSb can achieve one-way transmission for one photonic spin state but not for linear polarization (LP) state due to the chiral mirror-symmetry of the two spin states.…”

“…[ 17 ] By reasonably designing magneto‐optical material into the artificial microstructure to form the magneto‐optical photonic crystal, metasurface, and plasmonics, [ 18–23 ] the magneto‐optical effect from the material itself can be significantly enhanced, and some new physical mechanisms can be observed, such as the enhanced Faraday rotation, nonreciprocal topological edge states, and photonic spin Hall effect. [ 24–30 ]…”

Tailoring Circular Dichroism for Simultaneous Control of Amplitude and Phase via Ohmic Dissipation Metasurface

“…[ 1,2 ] Although often associated with biomolecules, chirality has intrigued a great deal of attention in relation to physics and material sciences. [ 3–9 ] Especially, chirality contributes to various exceptional phenomena under circularly polarized illumination that can be exceedingly useful for constructing electromagnetic devices. [ 10–12 ] Commonly, chiral structures possess the ability to rotate the plane of polarization and give rise to the effect of dichroism.…”