Topologically reconfigurable magnetic polaritons

Kirigami-Triggered Spoof Plasmonic Interconnects for Radiofrequency Elastronics

The flexible and conformal interconnects for electronic systems as a potential signal transmission device have great prospects in body-worn or wearable applications. High-efficiency wave propagation and conformal structure deformation around human body at radio communication are still confronted with huge challenges due to the lack of methods to control the wave propagation and achieve the deformable structure simultaneously. Here, inspired by the kirigami technology, a new paradigm to construct spoof plasmonic interconnects (SPIs) that support radiofrequency (RF) surface plasmonic transmission is proposed, together with high elasticity, strong robustness, and multifunction performance. Leveraging the strong field-confinement characteristic of spoof surface plasmons polaritons, the Type-I SPI opens its high-efficiency transmission band after stretching from a simply connected metallic surface. Meanwhile, the broadband transmission of the kirigami-based SPI exhibits strong robustness and excellent stability undergoing complex deformations, i.e., bending, twisting, and stretching. In addition, the prepared Type-II SPI consisting of 2 different subunit cells can achieve band-stop transmission characteristics, with its center frequency dynamically tunable by stretching the buckled structure. Experimental measurements verify the on-off switching performance in kirigami interconnects triggered by stretching. Overcoming the mechanical limitation of rigid structure with kirigami technology, the designer SPIs exhibit high stretchability through out-of-plane structure deformation. Such kirigami-based interconnects can improve the elastic functionality of wearable RF electronics and offer high compatibility to large body motion in future body network systems.

Reconfigurable origami hologram based on deep neural networks

Reconfigurable and multifunctional metasurfaces are becoming indispensable in a variety of applications due to their capability to execute diverse functions across various states. However, many of these metasurfaces incorporate complex active components, thereby escalating structural complexity and bulk volume. In this research, we propose a reconfigurable passive hologram based solely on an origami structure, enabling the successful generation of holograms depicting the 'Z' and 'L' illuminated by a right-hand circular polarization (RHCP) wave in two distinct states: planar and zigzag configuration, respectively. The transformation between the 2D planar metasurface and the 3D zigzag structure with slant angles of 35 is achieved solely through mechanically stretching and compressing the origami metasurface. The phases on the origami metasurface are trained through a deep neural network which operates on the NVIDIA Tesla k80 GPU, with the total training process costing 11.88 s after 100 epochs. The reconfigurable scheme proposed in this research provides flexibility and ease of implementation in the fields of imaging and data processing.

Modular reprogrammable 3D mechanical metamaterials with unusual hygroscopic deformation modes

The majority of polymer-based materials demonstrate expansion upon absorbing water from the air. Mechanical metamaterials provide an interesting way to achieve unusual hygroscopic deformation. However, previous studies have only accommodated the limited tunability of negative hygroscopic expansion by theoretical analysis but have never involved other deformation modes. This work proposes modular reprogrammable 3D moisture-sensitive mechanical metamaterials with switchable hygroscopic deformation modes, which are built up of multi-material 3D-printed bi-material curved strips and cubic nodes. Depending on the geometrical parameters and spatial layouts of the curved strips, the metamaterials exhibit tunable coefficient of hygroscopic expansion from negative to positive. In addition to homogeneous deformation, complex 3D hygroscopic deformation modes can be achieved including shear and twist. More interestingly, the metamaterials are reprogrammable since all the deformation modes can be switched by modular disassembling and reassembling of the curved strips, just like LEGO building blocks. This work demonstrates a feasible approach to achieve customized 3D hygroscopic deformation through easy block building for specific engineering applications including eliminating hygroscopic stress, shape morphing structures, and smart actuators.

Dual-Channel Surface Waves Directional Radiation with Customizable Intensity and Switchable Pattern

Achieving the conversion from surface waves (SWs) to propagating waves has captivated long-standing interest, and various ingenious metasurfaces benefiting from the powerful control capability for electromagnetic waves are able to realize efficient SWs directional radiation. Nevertheless, most existing schemes still suffer from the bottlenecks of single radiation channel, uncontrollable radiation intensity, and immutable radiation pattern, which immensely hinder their practical application in high-integration intelligent devices. Herein, a series of appealing strategies are proposed to achieve the dual-channel SWs directional radiation with customizable radiation intensity and switchable radiation pattern. The dual-channel SWs radiation metadevice based on the phase modulation metasurface is designed to directionally radiate SWs in left-handed circular polarized channel and right-handed circular polarized channel and possesses the broadband frequency scanning characteristic. More strikingly, the intensity-customizable dual-channel SWs radiation metadevice loaded with lumped resistors can control the realized gain of two circular polarized radiation beams, and the pattern-switchable dual-channel SWs radiation metadevice loaded with PIN diodes can dynamically adjust the radiation direction of the radiation beams. Numerous simulations and experiments of the proof-of-concept prototypes with modular design corroborate the theoretical predictions. Our methodology shows unprecedented flexibility in regulating SWs directional radiation and has enormous potential in engineering applications.

Low loss sensitivity of the anapole mode in localized defective nanoparticles

The excitation of a nonradiating anapole in a high-index dielectric nanosphere is an effective pathway for enhancing light absorption. Here, we investigate the effect of localized lossy defects on the nanoparticle based on Mie scattering and multipole expansion theories and find its low sensitivity to absorption loss. The scattering intensity can be switched by tailoring the defect distribution of the nanosphere. For a high-index nanosphere with homogeneous loss distributions, the scattering abilities of all resonant modes reduce rapidly. By introducing loss in the strong field regions of the nanosphere, we achieve independent tuning of other resonant modes without breaking the anapole mode. As the loss increases, the electromagnetic scattering coefficients of the anapole and other resonant modes show opposite trends, along with strongly suppressed corresponding multipole scattering. While regions with strong electric fields are more susceptible to loss, the anapole's inability to emit or absorb light as a dark mode makes it hard to change. Our findings provide new opportunities for the design of multi-wavelength scattering regulation nanophotonic devices via local loss manipulation on dielectric nanoparticles.