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Here we proposed and demonstrated two meta-atoms assisted H-type photoconductive antennas (PCAs) with novel features. The first one has all-dielectric nanopillars in the PCA gap which substantially enhance the absorption of the femtosecond laser pump, and thus realize a 1.94-fold increase on the emitted THz amplitude. The second PCA employs micron-scale metallic split-ring resonators (SRRs) to manipulate the terahertz wave propagating in the coplanar transmission lines, which can manipulate the spectrum of the far-field terahertz field. The reported results may extend and deepen the studies on metamaterial assisted PCAs.

Plasmonic metasurfaces have important applications in life science, optics, and catalysis. However, their industrial usage is limited by the challenges of high throughput nanofabrication. A promising solution is the transfer of a pattern into a substrate using block copolymers, nanostructured stamps or molds to create binary, three dimensional templates, which can then be decorated with plasmonically active metals. Here, we report on the optical properties of quasi-Babinet complementary arrays in the non-retarded regime investigated by finite-difference time-domain simulations. The structures consist of a nanopillar support, which is covered with metal disks on top of the pillars and a quasi-Babinet complementary hole array film at the base of the pillars. Strong vertical plasmonic coupling occurs for small separation distances of the plasmonic slabs. We present a comprehensive study of the near and far-field properties of such vertically coupled plasmonic arrays varying their critical geometric dimension and the employed metals with their intrinsic plasmonic material properties. In particular, we consider gold, silver, copper, aluminum, nickel, and palladium. Furthermore, the effect of the refractive index n of the nanopillar support between the range of n = 1.4 to n = 3.4 is investigated. The plasmonic slabs show tunable extraordinary transmission and large electric near-field enhancements, which are strongly dependent on the employed material and geometry. Further, we show that the templates are suitable for plasmonic heterostructures commonly used in plasmon-enhanced photocatalysis.

Nanopillars have been extensively explored as promising substrates for surface-enhanced Raman scattering (SERS) owing to their high sensitivity and excellent reproducibility. Most of the researches have been focused on the fabrication methods of nanopillars, and the dependences of SERS effects on geometrical size and spatial order are rarely investigated. In this work, SERS properties of nanopillars with different sizes (115–185 nm) and spatial orders (square and rhombus orders) have been studied. The work has shown that the nanopillars not only have high enhancement capability and high signal reproducibility, but also the enhancement is insensitive to the size and spatial orders. The measured enhancement factors (EFs) are 2.3–4.0 × 106 and signal reproducibility (relative standard deviation, RSD) are ∼ 5.2%–6.9%, which are among the best of the similar SERS substrates reported. The variation of SERS intensity was as low as approximately 4.8% with the variation of pillar size from 115, 135, 145, to 160 nm. The insensitiveness and high reproducibility have been ascribed to the combined excitation of localized surface plasmon resonance (LSPR) and propagating surface plasmons (SPPs) of the nanopillars. Optical properties of the nanopillars are studied both experimentally and numerically to understand the physics behind the SERS performance.

Structures consisting of a single Si nanodot buried within an insulating nanometric ${\mathrm{SiO}}_{2}$ layer stacked between two Si layers show promising properties for room temperature operational single-electron transistors. Moreover, such structures are highly compatible with modern complementary metal-oxide semiconductor technologies. Metastable ${\mathrm{SiO}}_{\mathrm{x}}$ phase separates into a Si nanodot and insulating, homogeneous ${\mathrm{SiO}}_{2}$ during annealing, providing a solid path towards the desired structure. However, achieving the necessary amount of excessive Si, dissolved in the ${\mathrm{SiO}}_{2}$ for correct concentrations of ${\mathrm{SiO}}_{\mathrm{x}}$, remains a technological challenge. In this work, we investigate ion-induced atom mixing in pre-built $\mathrm{Si}/{\mathrm{SiO}}_{2}/\mathrm{Si}$ nanopillars, which is considered to be a technologically promising way to produce the necessary concentrations of spatially confined ${\mathrm{SiO}}_{\mathrm{x}}$ in a controlled manner. During the high-fluence ion irradiation, we notice a significant shortening of the nanopillar and preferential loss of O atoms. Both sputtering and nanoscale ion hammering are found to be the cause of the deformation. The ion-hammering effect on nanoscale is explained by multiple small displacements, strongly enhanced after the nanopillar was rendered completely amorphous. The methods presented here can be used to determine the ion-fluence threshold for sufficient atom mixing in spatially confined regions before the large structural deformations are formed.

Resonant propagation of light is important for building novel light source and chip-scale optical interconnects. Here, we introduced an optoplasmonic amplifier which is operating in the visible range and generating Raman signal internally with injection seeding. We introduced the microspheres as a chain with different arrangements such as – single sphere; two spheres with equal and unequal sizes; three spheres with equal sizes and multi spheres with different sizes. We analyzed the effect of excitation and polarization with respect to different spheres and position of excitation. We noticed a shift of mode position with respect to different sizes of microspheres. We also had different kind of underlying substrates such as silicon nanopillar, polymer nanopillar, pyramid polymer and nanohole polymer and investigate the effect of these substrates on various chains of microspheres.

We study the modification of fluorescence emission and decay rate of single fluorescent molecules in the near field of a periodic plasmonic nanostructure formed by a square lattice of Au hollow conical pillars with a periodicity of 250 nm. We perform nanometer-resolved imaging of the LDOS by simultaneously mapping the position and the decay rate of photoactivatable single-molecules with a novel super-resolved microscopy approach which enables multiplexed and super-resolved fluorescence lifetime imaging at the single-molecule level (smFLIM) with a field of view of ~10 µm2. We observe the LDOS modification of such optically rich material at different illumination conditions and we measure a large Purcell factor enhancement which increases for oblique illumination of the nanostructure.

The ultra-thin optical structures of high-refractive-index materials can be used to control light at the subwavelength scale. In this work, we examine the scattering properties as well as reflection, transmission, and change of light phase in various high-index nanopillars supporting Mie resonances.

The concept of parity-time (PT) symmetry has recently expanded the toolbox to achieve active tunability in metasurfaces by modulating the imaginary part of the refractive index. In this work, we propose a hybridized static-active platform to dynamically tune the intensity and angular response of light by varying the non- Hermiticity factor in an all-dielectric metasurface. We numerically demonstrate tunable asymmetric transmission with respect to gain or loss side incidence in a vertically stacked Mie-resonant GaInP phased-array metasurface. It should be noted that the proposed system is reciprocal despite asymmetric transmission as the materials considered are in a linear regime. The primary building block consists of four PT-symmetric nanopillars of varying radii to achieve sufficient phase sampling. The overall design parameters are optimized for operation at a wavelength of 655 nm (typical PL emission peak of GaInP). For loss side normal incidence, the transmission is predominantly in the 0th diffraction order (ηl0~ 0:80, ηl1~ 0:18), while for gain side normal incidence, an amplified transmission is in the 1st order (ηg 0~ 0:02, ηg 1~0:78). The observed asymmetric transmission is due to the near-field coupling between different Mie multipoles, broken in-plane mirror symmetry (meta-atoms with increasing radii along the x-axis), and the broken PT-phase along the propagation direction. An asymmetry factor, ~0:9, is observed at λ = 655 nm. The symmetry in transmission can be restored by reducing the gain-loss contrast. We believe an optimal arrangement of gain-loss resonators combined with tunable pumping (either optically or electrically) could pave the way towards practical reconfigurable metasurfaces.

Semiconductor nanowire arrays have been demonstrated as promising candidates for nanoscale optoelectronics applications due to their high detectivity as well as tunable photoresponse and bandgap over a wide spectral range. In the infrared (IR), where these attributes are more difficult to obtain, nanowires will play a major role in developing practical devices for detection, imaging and energy harvesting. Due to their geometry and periodic nature, vertical nanowire and nanopillar devices naturally lend themselves to waveguide and photonic crystal mode engineering leading to multifunctional materials and devices. In this paper, we computationally develop theoretical basis to enable better understanding of the fundamental electromagnetics, modes and couplings that govern these structures. Tuning the photonic response of a nanowire array is contingent on manipulating electromagnetic power flow through the lossy nanowires, which requires an intimate knowledge of the photonic crystal modes responsible for the power flow. Prior published work on establishing the fundamental physical modes involved has been based either on the modes of individual nanowires or numerically computed modes of 2D photonic crystals. We show that a unified description of the array key electromagnetic modes and their behavior is obtainable by taking into account modal interactions that are governed by the physics of exceptional points. Such models that describe the underlying physics of the photoresponse of nanowire arrays will facilitate the design and optimization of ensembles with requisite performance. Since nanowire arrays represent photonic crystal slabs, the essence of our results is applicable to arbitrary lossy photonic crystals in any frequency range.

Two-photon states emitted from spontaneous parametric downconversion (SPDC) can exhibit quantum correlations in various degrees of freedom. On the other hand, plasmonic nanostructures show enhanced transmission thanks to the conversion of light into surface plasmon polaritons. It has been shown previously that polarization, time-energy and orbital angular momentum entanglement are preserved in such structures. The fact that surface plasmons are collective charge density waves, consisting of billions of electrons makes this observation remarkable. Here we show that spatial entanglement is also preserved by characterizing it after the photons interacted with gold nanopillar arrays. The detection is realized with novel single photon avalanche diode (SPAD) arrays with high spatial and temporal resolution. By measuring the spatial correlations of the photon in the near- and far-fields, we can characterize the state with respect to spatial entanglement with and without the nano-structure.

In this paper, a direct and cost-effective sol-gel method enables to produce stable titanium dioxide and titanium oxynitride photoresists is described. This approach is compatible with many photolithographic techniques. We show that laser interference lithography and nanosphere lithography can be used, respectively, to obtain homogeneous TiO2 diffraction gratings and periodic nanopillars over large areas. Further developments permit to transform TiO2 microstructured based sol-gel to TiN metallic microstructured layer, with good optical properties, by using an innovative rapid thermal nitridation process, which opens the way towards plasmonics and NIR filters based on periodic metallic microstructured layers.

Mechanically flexible and electrically conductive nanostructures are highly desired for flexible piezoresistive pressure sensors toward health monitoring or robotic skin applications. The popular approach for these sensors is to combine flexible but insulating polymers as a micro- or nanostructural functional medium and conductive materials covering the polymer surface, which could give rise to many practical issues, for example, durability, compatibility, and complicated processing steps. We herein report a piezoresistive pressure sensor with a functional component of nanopillars of a doped semiconducting polymer, operating at low bias voltage with a sensing mechanism based on controlled buckling. Nanopillars of poly(3-hexylthiophene-2,5-diyl) doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane are patterned using anodic aluminum oxide templates. The nanopillars impart reversible current changes in response to the applied pressure over a wide pressure range (0-400 kPa). The sensor exhibits two current response regimes. Below 50 kPa, a strongly nonlinear response is observed, and above 50 kPa, a linear pressure response is demonstrated. Euler buckling theory is used to predict the deformation behavior of the nanopillars under pressure and in turn elucidate the sensing mechanism. Our results demonstrate that the contact area between the nanopillars and the top electrode increases with the application of pressure due to their elastic buckling in a two-regime fashion underlining the two electrical current response regimes of the sensor. Independent finite element modeling and scanning electron microscopy measurements corroborated this sensing mechanism. In contrast to many reported pressure sensors, the controlled elastic buckling of the nanopillars enables the detection of pressure over a wide range with good sensitivity, excellent reproducibility, and cycling stability.

We made nanopillars with intervals of several tens of nanometers and diameter, and examined wettability. When the interval is narrow, the capillary phenomenon can be suppressed and hydrophobicity is realized. On the other hand, when the interval was widened, the wettability decreased due to the capillary phenomenon. As a result, it was found that the Cassie-Baxter model with filling factor gives a hydrophobic effect as the wetting property becomes narrower.

High efficient and durable catalysts are always needed to lower the kinetic barriers as well as prolong the service life associated with oxygen evolution reaction (OER). Herein, a sequential synthetic strategy is considered to prepare a hierarchical nanostructure, in which each component can be configured to achieve their full potential so that endows the resulting nanocatalyst a good overall performance. In order to realize this, well-organized cobalt oxide (Co3O4) nanopillars are firstly grown onto ultrathin 1T-molybdenum sulfide (1T-MoS2) to obtain high surface area electrocatalyst, providing electron transfer pathways and structural stability. After that, zeolitic imidazolate framework-67 (ZIF-67) derived carbonization film is further in situ deposited on the surface of nanopillars to generate plentiful active sites, thereby accelerating OER kinetics. Based on the combination of different components, the electron transfer capability, catalytic activity and durability are optimized and fully implemented. The obtained nanocatalyst (defined as 1T-MoS2/Co3O4/CN) exhibits the superior OER catalytic ability with the overpotential of 202 mV and Tafel slope of 57 mV·dec-1 at 10mA·cm-2 in 0.1 M KOH, and good durability with a minor chronoamperometric decay of 9.15 % after 60000 s of polarization.

We have demonstrated a thermally managed Si nanopillar/SiGe composite structure. Our fabricated defect-free Si nanopillar channel structure showed a 1/100 times lower thermal conductivity than Si bulk thanks to the control of the phonon transports. The results of thermal conductivity measurements clarified that the nanopillar structure could eliminate electron-phonon scattering. As such, this structure represents a promising solution for advanced CMOS technologies.

The nanopillar growth method of deposition of metal-organic molecules by a sharply focused electron beam is used to form high aspect ratio AFM probe. It is applied to AFM-based digital twin development of two-tier silicon carbide field emission array (FEA), made in SPETU LETI by a two stage reactive ion etching technique in a fluoride atmosphere with high-density emission tips (of the second stage) and vertically oriented surface morphology. In digital twin approach the experimental information describing the detailed surface morphology are represented by a numerical multiscale simulation.

International audience; Self-synchronization is a ubiquitous phenomenon in nature, in which oscillators are collectively locked in frequency and phase through mutual interactions. While self-synchronization requires the forced excitation of at least one of the oscillators, we demonstrate that this mechanism spontaneously appears due to activation from thermal fluctuations. By performing molecular dynamics simulations, we demonstrate self-synchronization in a platform supporting doped silicon resonator nanopillars having different eigenfrequencies. We find that pillar's vibrations are spontaneously converging to the same frequency and phase. In addition, the dependencies on the intrinsic frequency difference and the coupling strength agree well with the Kuramoto model predictions. More interestingly, we find that a balance between energy dissipation resulting from phonon-phonon scattering and potential energy between oscillators is reached to maintain synchronization. The balance could be suppressed by increasing the membrane size. While microscopic stochastic motions are known to follow random probability distributions, we finally prove that they can also yield coherent collective motions via self-synchronization.

Extensive research efforts have been devoted to the study and development of III-V compound semiconductor nanowires (NWs) and nanopillars (NPs) because of their unique physical properties and ability to form high quality, highly lattice-mismatched axial and radial heterostructures. These advantages lead to precise nano-bandgap engineering to achieve new device functionalities. One unique and powerful approach to realize these NPs is by catalyst-free, selective-area epitaxy (SAE) via metal-organic chemical vapor deposition, in which the NP location and diameter can be precisely controlled lithographically. Early demonstrations of electronic and optoelectronic devices based on these NPs, however, are often inferior compared to their planar counterparts due to a few factors: (1) interface/surface states, (2) inaccurate doping calibration, and (3) increased carrier scattering and trapping from stacking fault formation in the NPs. In this study, the detailed growth mechanisms of different III-As, III-Sb and III-P NPs and their heterostructures are investigated. These NPs are then fabricated into single-NP field-effect transistors (FETs) to probe their electrical properties. It is shown that these devices are highly diameter-dependent, mainly because of the effects of surface states. By growing a high band-gap shell around the NP cores to passivate the surface, the device performance can be significantly improved. Further fabrication and characterization of vertical surround-gate FETs using a high-mobility InAs/InP NP channel is also discussed. Aside from the radial NP heterostructures, different approaches to achieve purely axial heterostructures in InAs/In(As)P materials are also presented with excellent interface quality. Both single barrier and double barrier structures are realized and fabricated into devices that show carrier transport characteristics over a barrier and even resonant tunneling behavior. Antimonide-based NPs are also studied for their immense application in high-speed electronics and mid-IR optoelectronics. Different growth regimes are probed to achieve InSb NPs and InAsSb NPs.

We report on a new method for the fabrication of a large-area nanoscaled Au pattern on the Si substrate suitable for its uniform metal-assisted chemical etching (MACE) and the formation of nanopillar and nanowire arrays. The method is based on the formation of a thin, water-soluble adhesive layer on the Si substrate surface, which provides a high-quality nanotransfer printing of the Au nanopattern. In the final step, the water-soluble adhesive layer is removed and a structure suitable for MACE is formed. The problem of removing the adhesive layer without damaging and deforming the Au nanopattern was solved in our work. The capabilities of the method were demonstrated by the formation of a perfect Au nanomesh with the cell size of 80 nm, a period of 180 nm and an area of more than 4 cm2 on the Si substrate. A subsequent MACE of the substrate using the formed Au nanomesh made it possible to create a uniform ordered array of Si nanopillars with the cross-section of 80 nm × 80 nm and 1 µm long. The proposed method is simple and can be easily implemented on solid substrates on the areas exceeding 150 cm2.

To meet the fast-growing need for broad applications in remote sensing, novel optoelectronic devices with high detectivity in full bands and room temperature operation are urgently desired. This paper reports our progress in developing a specially designed photovoltaic detector by integrating a monolayer graphene onto a silicon-based nanopillar array standing on a p-n junction. Optoelectronic measurements of the fabricated detectors show that the monolayer graphene plays a critical role in device performance. Compared with the one without the graphene covering, the new device demonstrates significant improvements in the specific detectivity of 1.43 × 1013 Jones and the responsivity exceeding ∼106 V/W with a reduced leakage current corresponding to a quantum efficiency of 74.8% at 860 nm wavelength. Moreover, such sensing performance remained unaffected over the entire band from 450 to 1100 nm at room temperature, which is suitable for broadband imaging applications.

Herein, a rigid 3D DNA nanopillar was used to investigate the influence of spatial organization on the cascade activity in multienzyme systems, realizing controllable regulation of the mimic enzyme ratio and spacing for acquiring a high-efficiency enzyme cascade catalytic platform. Initially, the ratio of mimic enzyme AuNPs (glucose oxidase-like activity) and hemin/G-quadruplex DNAzyme (peroxidase-like activity) fixed at the designed position was adjusted by changing the number of edges in a DNA polyhedron, resulting in an optimal mimic enzyme ratio of 1 : 4 with a quadrangular prism as the scaffold. Notably, the DNA nanopillar formed by quadrangular prism layer-by-layer assembly acted as a track for directional and controllable movement of a bipedal DNA walker based on the toehold mediated strand displacement reaction (TSDR), which endowed the assay system with continuous enzyme spacing regulation compared with previous enzyme cascade systems that induced inflexible operation. Furthermore, enzyme mimetics in this work circumvented the drawbacks of natural enzymes, such as time-consuming purification processes and poor thermal stability. As a proof of concept, the proposed dual regulation strategy of cascade enzymes was applied in the ultrasensitive electrochemical detection of Pb2+, which provided a new route to fabrication of high-performance artificial enzyme cascade platforms for ultimate application in bioanalysis and biodiagnostics., A rigid 3D DNA nanopillar was used to investigate the influence of spatial organization on the cascade activity in multienzyme systems, realizing controllable regulation of the mimic enzyme ratio and spacing for efficient cascade catalytic platform.

Plasma membrane topography has been shown to strongly influence the behavior of many cellular processes such as clathrin-mediated endocytosis, actin rearrangements, and others. Recent studies have used 3D nanostructures such as nanopillars to imprint well-defined membrane curvatures (the “nano-bio interface”). In these studies, proteins and their interactions were probed by 2D fluorescence microscopy. However, the low resolution and limited axial detail of such methods are not optimal to determine the relative spatial position and distribution of proteins along a 100 nm-diameter object, which is below the optical diffraction limit. Here, we introduce a general method to explore the nanoscale distribution of proteins at the nano-bio interface with 10-20 nm precision using 3D single-molecule super-resolution (SR) localization microscopy. This is achieved by combining a silicone oil immersion objective and 3D double-helix point-spread function microscopy. We carefully optimize the objective to minimize spherical aberrations between quartz nanopillars and the cell. To validate the 3D SR method, we imaged the 3D shape of surface-labeled nanopillars and compared the results with electron microscopy measurements. Turning to transmembrane-anchored labels in cells, the high quality 3D SR reconstructions reveal the membrane tightly wrapping around the nanopillars. Interestingly, the cytoplasmic protein AP-2 involved in clathrin-mediated endocytosis accumulates along the nanopillar above a specific threshold of 1/R membrane curvature. Finally, we observe that AP-2 and actin preferentially accumulate at positive Gaussian curvature near the pillar caps. Our results establish a general method to investigate the nanoscale distribution of proteins at the nano-bio interface using 3D SR microscopy.

Nanolight sources employing III-V GaAs semiconductor materials as the gain medium are crucial for the fabrication of miniaturized optical sources such as nanoLEDs and nanolasers with emerging applications in 3D sensing, optical data communication, spectroscopy, medical diagnosis and even neuromorphic computing [1] . However, the surfaces of GaAs-based compounds and their interfaces with dielectrics tend to host large densities of electronically active defects. Particularly, when the devices are scaled to the deep subwavelength size (<

Gold nanojets with various morphologies, from nanopillar to nanotip with up to 800 nm height, and finally to nanotip with droplet, are fabricated on gold thin film by a femtosecond laser irradiation. The near-field localized surface plasmon resonance (LSPR) and photothermal effects of gold nanojets are studied through finite element electromagnetic (EM) analysis, supporting in nanojets design for potential applications of high-resolution imaging, nanomanipulation and sensing. For an individual nanotip, the confined electron oscillations in LSPR lead to an intense local EM field up to three orders of magnitude stronger than the incident field strength at the end of gold tip, where the vertical resolution for the field enhancement was improved down to nanoscale due to the small size of the sharp gold tip (5-nm-radius). At specific wavelength, nanopillar can serve as an effective light-to-heat converter and its heating can be fine-tuned by external irradiation, and its dimension. The long-range periodic nanojet arrays (periods from 1.5 µm to 2.5 µm) with different geometry were printed using several pulse energy levels. By confining more light into the tip (two orders of magnitude stronger than single tip), nanotip array shows more pronounced potential to serve as a refractometric sensor due to their high sensitivity and reproducibility. These results promote fs laser printing as a high-precision tool for nanoarchitecture in optical imaging, nanomanipulation and sensing application.

Subwavelength sized on-chip coherent light sources are attractive for variety different applications, such as integrated optical interconnects [1] , super resolution imaging [2] and neuromorphic computing [3] . Practical demonstration of nanolasers brings a number of challenges, including the nanostructures sensitivity to the fabrication defects. High surface-to-volume ratio makes surface defects detrimental for lasing performance. To minimize the impact of non-radiative surface recombination, many surface passivation methods have been reported [4] . For InGaAs material, significant photoluminescence (PL) signal improvement has been observed for the combination of ammonium sulphide ((NH 4 ) 2 S) treatment and a thin SiO x layer coating deposited on the surface by plasma enhanced chemical vapour deposition (PECVD) [5] . Such passivation method may be promising for practical devices only if it is stable for high temperatures, since the fabrication of optoelectronic devices requires a number of high-temperature processes like rapid thermal annealing (RTA) for ohmic contacts formation. So far, the quality of the ammonium sulfide passivated surface has been shown to degrade upon annealing at temperatures above 300 °C [6] . In this work, we show photoluminescence performance improvement after ammonium sulphide and SiO x coating passivation and its stability in a subsequent high temperature treatment.

Despite extensive studies there are contradictory findings regarding effects of nano-topography on bacterial adherence and viability. Here, we report that bacteria have ability to locate nearest pillars, enabling itself to expand and attach, and pulling these pillars towards itself. Two types of nanopillars, namely, Straight pillars (SP) and Conical pillars (CP) were used to investigate the behavior of bacterial cell on surface nano topographies. We calculated that the force applied by the bacteria on these pillars is in the order of few hundred nano-newtons, and most importantly, the magnitude of the applied force depends on the pillar dimensions. Straight pillars are bent significantly compared to sharp-tipped conical pillars, suggesting higher overall mechanical stress in/throughout the bacterial membrane on straight pillars, leading to membrane rupture and ultimately cell death. In the case of bacterial membrane on conical pillars, severe localized stress generated in the membrane, near the regions where pillars contacted the membrane due to small cross-section of conical pillars, pierces the membrane (no bending of pillars) which causes cell death.

Complex environmental factors and various coexisting interference factors can easily affect the sensitivity and selectivity of gas sensors, hindering their performance. In this work, a high sensitivity gas sensor with ZnO nanospikes coupled nanopillar array is proposed. The unique hierarchical nanostructure is composed of wafer-level Si nanopillar array and hydrothermal synthesized ZnO nanospikes on the surface. It is highly repellent to liquids and oily fluids with low surface tension. It has been successfully applied to ethanol gas sensors with good sensitivity, repeatability, and good stability even after surface contamination. This work provides a promising method for the design of reliable gas sensors with anti-environmental contamination performance.

A metal-dielectric-metal nanopillar metasurfaces with variable three-dimensional sizes is proposed and experimentally demonstrated to achieve anomalous deflection at different angles with different phase gradients. Theoretical studies have shown that subwavelength nanopillar with different lengths, widths and heights on a glass substrate can achieve high amplitude response and complete 2π phase delay in the reflection field. Anomalous deflection metasurfaces with three phase gradients of π/2, π/4 or π/8 in supercell units composed of 4, 8, or 16 nanopillars of different sizes working at wavelength of 1550 nm are designed and investigated. Under linearly polarized normal incident beam, the anomalous deflection angles of the three phase gradients are, respectively, 23.97°, 12.21° and 5.87° with a reflection of 83%, which is consistent with the generalized Snell's theory. The negative refraction and total reflection phenomenon under the oblique incident beams are generated in the case of phase gradient of π/4, which are completely consistent with the numerical results. Using two-photon laser direct writing technology, a metasurface with π/2 phase gradient nanopillar was fabricated on a 170 μm thick borosilicate glass substrate. The anomalous deflection angle measured by infrared polarization detection is 24°, which is essentially the same as the designed value. The demonstrated work provides a new way for realizing artificial control of electromagnetic wave propagation in optical communication and other fields.