Semi-Ellipsoid Nanoarray for Angle-Independent Plasmonic Color Printing

Employing a silver nano semi-ellipsoid nanoarray with high symmetry into applications in plasmonic color printing,we fulfill printing images with colors independent of observing angles.Also,by decreasing the period of a nano semi-ellipsoid array into deep-subwavelength scales,we obtain high reflectivity over 50%,promising high efficiency for imaging generations.A facile technique based on the transfer of anodized aluminum oxide template is developed to fabricate the silver nano semi-ellipsoid nanoarray,realizing plasmonic color printing with features of low cost,scalable,full color and high flexibility.Our approach provides a feasible way to address the angledependent issue in the previous practice of plasmonic color printing,and boosts this field on its way to real-world commercial applications.

Perturbative countersurveillance metaoptics with compound nanosieves

The progress of metaoptics relies on identifying photonic materials and geometries,the combination of which represents a promising approach to complex and desired optical functionalities.Material candidate options are primarily limited by natural availability.Thus,the search for meta-atom geometries,by either forward or inverse means,plays a pivotal role in achieving more sophisticated phenomena.Past efforts mainly focused on building the geometric library of individual meta-atoms and synthesizing various ones into a design.However,those efforts neglected the powerfulness of perturbative metaoptics due to the perception that perturbations are usually regarded as adverse and in need of being suppressed.Here,we report a perturbation-induced countersurveillance strategy using compound nanosieves mediated by structural and thermal perturbations.Private information can be almost perfectly concealed and camouflaged by the induced thermal-spectral drifts,enabling information storage and exchange in a covert way.This perturbative metaoptics can self-indicate whether the hidden information has been attacked during delivery.Our results establish a perturbative paradigm of securing a safer world of information and internet of things.

Giant enhancements of high-order upconversion luminescence enabled by multiresonant hyperbolic metamaterials

Photonic nanostructures with resonant modes that can generate large electric field(EF) enhancements are applied to enhance light-matter interactions in nanoscale, bringing about great advances in both fundamental and applied science. However, a small hot spot(i.e., the regions with strong EF enhancements) and highly inhomogeneous EF distribution of the resonant modes usually hinder the enhancements of light-matter interactions in a large spatial scale. Additionally, it is a severe challenge to simultaneously generate multiple resonant modes with strong EF enhancements in a broadband spectral range, which greatly limits the capacity of a photonic nanostructure in boosting optical responses including nonlinear conversion, photoluminescence, etc. In order to overcome these challenges, we presented an arrayed hyperbolic metamaterial(AHMM). This AHMM structure is applied to simultaneously enhance the three-photon and four-photon luminescence of upconversion nanoparticles. Excitingly, the enhancement of the three-photon process is 1 order of magnitude larger than previous records, and for the enhancing four-photon process, we achieve an enhancement of 3350 times, greatly beneficial for overcoming the crucial problem of low efficiency in near infrared light upconversion. Our results demonstrated a promising platform for realizing giant enhancements of light-matter interactions, holding potential in constructing various photonics applications such as the nonlinear light sources.

Integrating lattice and gap plasmonic modes to construct dual-mode metasurfaces for enhancing light–matter interaction

Photonic structures with optical resonances beyond a single controllable mode are strongly desired for enhancing light±matter interactions and bringing about advanced photonic devices. However, the realization of effective multimodal photonic structures has been restricted by the limited tunable range of mode manipulation, the spatial dispersions of electric fields or the polarization-dependent excitations. To overcome these limitations, we create a dualmode metasurface by integrating the plasmonic surface lattice resonance and the gap plasmonic modes;this metasurface offers a widely tunable spectral range, good overlap in the spatial distribution of electric fields, and polarization independence of excitation light. To show that such dual-mode metasurfaces are versatile platforms for enhancing light±matter interactions, we experimentally demonstrate a significant enhancement of second-harmonic generation using our design, with a conversion efficiency of 1±3 orders of magnitude larger than those previously obtained in plasmonic systems. These results may inspire new designs for functional multimodal photonic structures.