Optically and vibrationally resonant nanophotonic devices are of particular importance for their ability to enhance optomechanical interactions, with applications in nanometrology, sensing, nano-optical control of light, and optomechanics. Here, the optically resonant excitation and detection of gigahertz vibrational modes are demonstrated in a nanoscale metasurface array fabricated on a suspended SiC membrane. With the design of the main optical and vibrational modes to be those of the individual metamolecules, resonant excitation and detection are achieved by making use of direct mechanisms for optomechanical coupling. Ultrafast optical pump−probe studies reveal a multimodal gigahertz vibrational response corresponding to the mechanical modes of the suspended nanoresonators. Wavelength and polarization dependent studies reveal that the excitation and detection of vibrations takes place through the metasurface optical modes. The dielectric metasurface pushes the modulation speed of optomechanical structures closer to their theoretical limits and presents a potential for compact and easily fabricable optical components for photonic applications.

Despite recent tremendous progress in optical imaging and metrology1–6, there remains a substantial resolution gap between atomic-scale transmission electron microscopy and optical techniques. Is optical imaging and metrology of nanostructures exhibiting Brownian motion possible with such resolution, beyond thermal fluctuations? Here we report on an experiment in which the average position of a nanowire with a thermal oscillation amplitude of ∼150 pm is resolved in single-shot measurements with subatomic precision of 92 pm, using light at a wavelength of λ = 488 nm, providing an example of such sub-Brownian metrology with ∼λ/5,300 precision. To localize the nanowire, we employ a deep-learning analysis of the scattering of topologically structured light, which is highly sensitive to the nanowire’s position. This non-invasive metrology with absolute errors down to a fraction of the typical size of an atom, opens a range of opportunities to study picometre-scale phenomena with light.

Time crystals are an eagerly sought phase of matter with broken time-translation symmetry. Quantum time crystals with discretely broken time-translation symmetry have been demonstrated in trapped ions, atoms and spins whereas continuously broken time-translation symmetry has been observed in an atomic condensate inside an optical cavity. Here we report that a classical metamaterial nanostructure, a two-dimensional array of plasmonic metamolecules supported on flexible nanowires, can be driven to a state possessing all of the key features of a continuous time crystal: continuous coherent illumination by light resonant with the metamolecules’ plasmonic mode triggers a spontaneous phase transition to a superradiant-like state of transmissivity oscillations, resulting from many-body interactions among the metamolecules, characterized by long-range order in space and time. The phenomenon is of interest to the study of dynamic classical many-body states in the strongly correlated regime and applications in all-optical modulation, frequency conversion and timing.

Huygens' meta-atom is the basic building unit of Huygens' metasurfaces allowing for almost arbitrary wavefront shaping across a surface. We here present a kind of Huygens' meta-atom by coupling a nanodisk to its Babinet-complementary structure (nanohole), and develop an optical lumped nanocircuit model to analyze vertical and lateral coupling effects and resonance frequencies. Simulation results show that the tuned coupling via lateral misalignment between the two nanostructures is sufficient to shape the wavefront without changing the dimensions or orientations of antennas. By tuning the coupling via lateral misalignment, we design a reflective gradient metasurface based on one coupled mode and a high-efficiency transmissive gradient metasurface working in the spectral overlap of electric and magnetic resonances to realize beam deflection. The proposed coupling-based Huygens' meta-atom is a new building block for plasmonic metasurfaces with enhanced light-matter interactions, high-efficiency and almost arbitrary wavefront shaping over the full electromagnetic spectrum.

The combination of optical and mechanical resonances offers strong hybrid nonlinearities, bistability, and the ability to efficiently control the optical response of nanomechanical photonic metamaterials with electric and magnetic field. While optical resonances can be characterized in routine transmission and reflection experiments, mapping the high‐frequency mechanical resonances of complex metamaterial structures is challenging. Here, it is reported that high‐frequency time‐domain fluctuations in the optical transmission and reflection spectra of nanomechanical photonic metamaterials are directly linked to thermal motion of their components and can give information on the fundamental frequencies and damping of the mechanical modes. This is demonstrated by analyzing time‐resolved fluctuations in the transmission and reflection of dielectric and plasmonic nanomembrane metamaterials at room temperature and low ambient gas pressure. These measurements reveal complex mechanical responses, understanding of which is essential for optimization of such functional photonic materials. At room temperature the magnitude of the observed metamaterial transmission and reflection fluctuations is of order 0.1% but may exceed 1% at optical resonances.