A magnetic actuation scheme for nano-kirigami metasurfaces with reconfigurable circular dichroism

Abstract

Nano-kirigami-based deformable metasurfaces offer unique advantages in the dynamic modulation of optical fields and the realization of reconfigurable micro-/nano-optoelectronic devices. Here, we theoretically propose and numerically demonstrate a magnetically actuated deformation scheme for 2D nano-kirigami structures, which can be accurately and continuously transformed from 2D to 3D. Based on the traditional pinwheel structure, an Fe/Au bilayer anti-pinwheel nanostructure is designed and dynamically transformed by employing magnetic attraction in numerical simulations, in which the ratio between deformation height and lateral period could reach up to 0.563. More importantly, it is found that the anti-pinwheel structure has superior circular dichroism (CD), whose maximum CD response could reach 7 times that of the corresponding pinwheel structure. Further analysis of the scattering power of multipole moments reveals that such a superior CD response is found to be induced by the handedness-dependent excitation of a toroidal dipole moment. Such a straightforward magnetically actuated deformation and novel anti-pinwheel structure provides useful methodologies to explore and realize deformable metamaterials and their dynamic regulation capabilities, as well as applications in chiral spectroscopy, optical reconfiguration, optical sensing, etc.

Magneto‐Mechanical Bilayer Metamaterial with Global Area‐Preserving Density Tunability for Acoustic Wave Regulation

“…In response, active metamaterials have emerged, which can transform between preprogrammed shapes when subjected to external stimuli, such as mechanical loads, [29][30][31][32] heat, [33][34][35][36] electrical currents, [37][38][39][40] or magnetic fields. [41][42][43][44] These shape transformations often involve internal deformations of the unit cells, which also change the area density and the overall dimensions of the metamaterial. However, a 2D metamaterial covers a specific area.…”

Optoelectronically navigated nano-kirigami microrotors

“…In recent years, with the rapid development of micro/nanofabrication technologies, the concept and design of kirigami have been extended to the scientific research in the microscopic world. The key significance lies in that nanoscale kirigami structures (named nano-kirigami) can support integrable 3D morphological transformations upon exposure to external stimuli in microscale, such as mechanical (20), thermal (21), electric (22), and magnetic (23) fields, leading to fundamental breakthroughs and useful applications in biomolecular engineering (24,25), chirality research (26)(27)(28)(29), and nanophotonics (22,27,(29)(30)(31). Therefore, creating versatile nano-kirigami structures with reconfigurable and transformable topology has become a prominent research objective.…”

Chiral Metasurfaces: A Review of the Fundamentals and Research Advances

“…Among these, metasurfaces, which are 2D artificial composite meta-atoms, stand out because of their advantageous fabrication process, cost, and capabilities. They feature characteristic electromagnetic (EM) wave-manipulating abilities similar to those of three-dimensional (3D) metamaterials and support a wide spectrum of designed optical responses owing to their comparative flexibility in structural fabrication [6][7][8][9][10][11][12][13][14][15][16][17][18]. Thus, metasurfaces that respond differently to LCP and RCP have emerged as recent academic and industrial hotspots [14][15][16][17][18][19][20][21].…”

“…Recent studies have shown that chiroptical responses such as CD and OR can be tuned using tunable chiral metasurfaces [7][8][9][10][11]58,[61][62][63][64][74][75][76][77]. The active modification of chiroptical responses in chiral metasurfaces is attained by external stimuli like electrical fields, magnetic fields, thermal change, or incident light, which changes the properties of individual atoms [58,66].…”