Guobang Jiang

Photonic crystals are typically fabricated with a fixed topology, freezing their edge and corner states in space and frequency. Here we introduce a kirigami-actuated reconfigurable topological photonic crystal in which a single in-plane rotation reshapes the unit cell, drives a bandgap closure and reopening, and thereby relocates the Wannier center and switches the associated Zak phase—the topological invariant that determines whether boundary states appear. We engineer a symmetry-preserving square-lattice deformation path that programs the intracell rod configuration into a compact, discrete topological phase library. Using this library, we demonstrate reconfigurable control of topological modes in both resonance frequency and spatial localization from the same mechanical degree of freedom. A higher-order corner mode is switched between two distinct resonance frequencies while its localization moves between different geometric corners. Meanwhile, at a fixed operating frequency, the propagation path of reciprocal crystalline-symmetry-protected edge modes is mechanically rewritten, enabling on/off gating and two-path beam routing. These results establish a route toward reconfigurable topological photonic devices, showing that quantized band topology can be encoded and switched by shape.

The symmetry of the phase profile dictates how a metasurface manipulates electromagnetic waves. Altering that symmetry therefore directly enables wave control. Conventional mechanical methods such as elastic stretching and single‐cell kirigami vary lattice spacings p _x , p _y and meta‐atom orientation but leave the ordering unchanged, limiting the accessible symmetries. Here, supercell kirigami is introduced, where several phase‐distinct meta‐atoms are mounted on each rigid panel. During actuation, the panels stretch, rotate, and, crucially, reorder their meta‐atom sequence. Guided by wallpaper group design principles, a variety of kirigami metasurfaces including rotating square and staggered rotating rectangle supercells, are fabricated, and experimentally realize five symmetry transitions, including the previously inaccessible pmm to p4m and pmm to pmg routes. Broadband measurements confirm wavefront conversions from dual to quad beams and redirection of reflected beams by 45°. Because the kirigami architecture is scale‐ and material‐independent, the same strategy readily extends to higher frequency regimes. Operating at the phase map level rather than relying on resonator physics, this approach can also be applied to acoustic and thermal metasurfaces and even photonic crystals, opening broad prospects for reconfigurable wave devices.

Dynamically controlling electromagnetic waves at will is highly desired in many applications, but most previously realized mechanically reconfigurable metasurfaces are of restricted wave-control capabilities due to the limited tuning ranges of structural properties (e.g., lattice constant or meta-atoms). Here, we present mechanically reconfigurable metasurfaces in which both lattice constants and local reflection phases of constitutional meta-atoms can be synchronously controlled based on the kirigami rotation transformation, thereby exhibiting extended tuning ranges and thus wave-control capabilities. In particular, such metasurfaces can exhibit continuously varied and even re-formed reflection-phase profiles along with the kirigami rotation transformation, serving as ideal platforms to achieve reconfigurable beam steering in pre-designed manners. Using this concept, we design and fabricate two kirigami metasurfaces, working as a beam flipper and as a beam splitter for microwaves, respectively, and experimentally characterize their wave-manipulation functionalities. Experimental results are in good agreement with full-wave simulations. The proposed idea is so general that it can be applied to realize reconfigurable metasurfaces with different materials/configurations or in high frequency regimes, for controlling electromagnetic waves and other classical waves (e.g., acoustic waves).

Releasing pre-strained two-dimensional nanomembranes to assemble on-chip three-dimensional devices is crucial for upcoming advanced electronic and optoelectronic applications. However, the release process is affected by many unclear factors, hindering the transition from laboratory to industrial applications. Here, we propose a quasistatic multilevel finite element modeling to assemble three-dimensional structures from two-dimensional nanomembranes and offer verification results by various bilayer nanomembranes. Take Si/Cr nanomembrane as an example, we confirm that the three-dimensional structural formation is governed by both the minimum energy state and the geometric constraints imposed by the edges of the sacrificial layer. Large-scale, high-yield fabrication of three-dimensional structures is achieved, and two distinct three-dimensional structures are assembled from the same precursor. Six types of three-dimensional Si/Cr photodetectors are then prepared to resolve the incident angle of light with a deep neural network model, opening up possibilities for the design and manufacturing methods of More-than-Moore-era devices.