Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

Abstract

Metamaterials with artificial optical properties have attracted significant research interest. In particular, artificial magnetic resonances with non-unity permeability tensor at optical frequencies in metamaterials have been reported. However, only non-unity diagonal elements of the permeability tensor have been demonstrated to date. A gyromagnetic permeability tensor with non-zero off-diagonal elements has not been observed at the optical frequencies. Here we report the observation of gyromagnetic properties in the near-infrared wavelength range in a magneto-plasmonic metamaterial. The non-zero off-diagonal permeability tensor element causes the transverse magneto-optical Kerr effect under s-polarized incidence that otherwise vanishes if the permeability tensor is not gyromagnetic. By retrieving the permeability tensor elements from reflection, transmission, and transverse magneto-optical Kerr effect spectra, we show that the effective off-diagonal permeability tensor elements reach 10−3 level at the resonance wavelength (~900 nm) of the split-ring resonators, which is at least two orders of magnitude higher than magneto-optical materials at the same wavelength. The artificial gyromagnetic permeability is attributed to the change in the local electric field direction modulated by the split-ring resonators. Our study demonstrates the possibility of engineering the permeability and permittivity tensors in metamaterials at arbitrary frequencies, thereby promising a variety of applications of next-generation nonreciprocal photonic devices, magneto-plasmonic sensors, and active metamaterials.

Circular Displacement Current Induced Anomalous Magneto‐Optical Effects in High Index Mie Resonators

“…In fact, from a metamaterial perspective, s-polarized TMOKE indicates non-zero off-diagonal components of the effective permeability tensor. [41][42][43] We can treat the Si/Ce:YIG/YIG layers as a metamaterial shown in Figure S9 (Supporting Information). Based on parameter retrieval and 4 × 4 transfer matrix methods, [42] we calculated the diagonal effective permittivity tensor elements(𝜀 ′ + j𝜀 ′′ ), diagonal effective permeability tensor elements(𝜇 ′ + j𝜇 ′′ ) and off-diagonal permeability tensor elements (𝜅 ′ + j𝜅 ′′ ) for s-polarized incident light with incident angle 𝜃 = 45°, as shown in Figure S9 (Supporting Information).…”

Review of optically active and nonlinear chiral metamaterials

“…Magneto-optic effect 54 Magneto-chiral dichroism 56,57 Transverse magneto-optical Kerr effect Voigt/magneto-electro-optical 95 Optical gyromagnetic 96 Gyrotropic 97 Mechanical MEMS/NEMS 53,60,61,64,65 Piezooptic effect Pneumatic 62 Thermal-mechanical expansion Photoelasticity/ stretching 63,66 Hydrogel absorption 67 Liquid crystal 75,76 Chemical/ biological DNA controlled 72 Chemical reaction 73 step is to look for novel materials and structures that efficiently complete the switching process.…”

Modeling of Enhanced Polar Magneto-Optic Kerr Effect by Surface Plasmons in Au Bowtie Arrays

“…Early MOSPR investigations concentrated on a few flat, pure ferromagnetic films, and to improve the MO effects, surface plasmon resonance (SPR) was activated on the surface of these films [ 13 , 14 , 15 ]. Later, ferromagnetic materials and noble metals were combined to create excellent magnetic plasmon devices that benefited from both the plasmon properties of noble metals and the MO properties of ferromagnetic materials [ 16 , 17 , 18 ]. Due to the great LSPR, the MOKE in the noble metal–ferromagnetic system can be significantly increased compared to the pure ferromagnetic material [ 19 , 20 ].…”