We demonstrate plasmonic color printing with subwavelength resolution using circular gap-plasmon resonators (GPRs) arranged in 340 nm period arrays of square unit cells and fabricated with single-step electron-beam lithography. We develop a printing procedure resulting in correct single-pixel color reproduction, high color uniformity of colored areas, and high reproduction fidelity. Furthermore, we demonstrate that, due to inherent stability of GPRs with respect to surfactants, the fabricated color print can be protected with a transparent dielectric overlay for ambient use without destroying its coloring. Using finite-element simulations, we uncover the physical mechanisms responsible for color printing with GPR arrays and suggest the appropriate design procedure minimizing the influence of the protection layer.
Refractorymetal-based broadband absorber/narrowband emitters is a flourishing field in energy harvesting where the physical and chemical stability of the metals at high temperatures provide efficient absorption/emission of solar/ heat energy. [1][2][3] Advancements in solar/ thermophotovoltaics (S/TPV) must be accompanied by thermally stable devices in order to withstand extreme operating conditions. The fundamental limiting factor [Shockley Queisser (SQ) efficiency limit] in traditional single-junction solar cells is its inability in converting the broad solar spectrum into a narrow range of wavelengths defined by the PV cells. [4] Solar photons with energies below the bandgap of the PV cell are not converted, and the photons with energies higher than the bandgap lose their additional energy through a process known as thermalization. In solar thermophotovoltaics (STPV), an intermediate system composed of absorber and emitter is used to overcome the SQ limit by harvesting the solar energy followed by the emission of narrowband radiation. [5] The absorber should provide unitary absorption in the entire solar spectral range over a range of incidence angles with polarization insensitive nature, and minimum thermal reradiation to avoid near-infrared heat radiation at elevated temperatures. Through thermal conduction, the absorbed heat energy is transferred to the emitter, which is tailored to emit a narrowband radiation defined by the bandgap energy of a PV cell. Thus, the absorber needs to withstand high temperatures to transfer a large amount of heat energy to the emitter. The low-loss noble metals are successfully used in unitary absorbers so far, particularly Au and Ag. [6][7][8] However, noble metals are not compatible with hightemperature photovoltaic applications and standard silicon manufacturing processes (complementary metal oxide semiconductor, CMOS, technology), owing to low melting point and diffusion of noble metals into silicon. Annealing the substrates at high temperatures induce oxidation, surface diffusion, corrosion, cracking, and delamination of thin films from the substrate. [7] The situation is even worse in the case of the Broadband absorbers, with the simultaneous advantages of thermal stability, insensitivity to light polarization and angle, robustness against harsh environmental conditions, and large area fabrication by scalable methods, are essential elements in (solar) thermophotovoltaics. Compared to the noble metal and multilayered broadband absorbers, high-temperature refractory metal-based nanostructures with low-Q resonators are reported less. In this work, 3D titanium nitride (TiN) nanopillars are investigated for ultrabroadband absorption in the visible and near-infrared spectral regions with average absorptivities of 0.94, over a wide range of oblique angles between 0° and 75°. The effect of geometrical parameters of the TiN nanopillars on broadband absorption is investigated. By combining the flexibility of nanopillar design and lossy TiN films, ultrabroadband absorption in the vi...
Efficient broadband absorption of visible and near-infrared light by low quality-factor metal-insulator-metal (MIM) resonators using refractory materials is reported. Omnidirectional absorption of incident light for broad angles of incidence and polarization insensitivity are observed for the fabricated MIM resonator. Excellent thermal stability of the absorber is demonstrated at high operating temperatures (800 °C). The experimental broadband absorption spectra show good agreement with simulations. The resonator with 12 nm top tungsten and 100 nm alumina spacer film shows absorbance above 95% in the range of 650 to 1750 nm. The absorption window is tunable in terms of the center wavelength, bandwidth, and the value of maximum absorbance (~98%) by simple variation of appropriate layer thicknesses. Owing to their flexibility, ease of fabrication and low cost, the presented absorbers have the potential for a wide range of applications, including the use in commonly used infrared bands or absorbers for (solar) thermo-photovoltaic energy conversion, where high absorbance and simultaneously low (thermal) re-radiation is of paramount importance.
On-chip manipulating and controlling the temporal and spatial evolution of light is of crucial importance for information processing in future planar integrated nanophotonics. The spin and orbital angular momentum of light, which can be treated independently in classical macroscopic geometrical optics, appear to be coupled on subwavelength scales. We use spin-orbit interactions in a plasmonic achiral nano-coupler to unidirectionally excite surface plasmon polariton modes propagating in seamlessly integrated plasmonic slot waveguides. The spin-dependent flow of light in the proposed nanophotonic circuit allows on-chip electrical detection of the spin state of incident photons by integrating two germanium-based plasmonic-waveguide photodetectors. Consequently, our device serves as a compact (~ 618 m 2 ) electrical sensor for photonic spin Hall dynamics.The demonstrated configuration opens new avenues for developing highly-integrated polarizationcontrolled optical devices that would exploit the spin-degree of freedom for manipulating and controlling subwavelength optical modes in nanophotonic systems.Introduction. Light carries both the spin, an intrinsic form of angular momentum, and orbital angular momentum, which determines its polarization and spatial degree of freedom. Interaction between the spin and orbital degrees of freedom of photons has evoked intensive investigations owing to its potential to push the development of technologies, such as chiroptical spectroscopy 1,2 , communication 3 , information processing 4 , topological photonics 5,6 and quantum computing 7 , to their full potential. The limiting factor for groundbreaking developments in those fields refers to the fact that the spin-orbit interactions (SOIs) in optics are usually very weak, akin to the Planckconstant smallness of the electron SOI found in solid-state spintronics 8 . A promising way to significantly enhance spin-controlled optical phenomena is to utilize light-matter interactions on the nanoscale that are especially strong in plasmonic nanostructures. It has been shown that geometrically chiral metallic structures, which do not superimpose onto their mirror image, can strongly enhance chiroptical far-field responses as a consequence of structural chirality 9-12 .Remarkably, even achiral structures exhibit the SOI potential in the near-field due to twisted trajectories of surface plasmons at a nanosphere [13][14][15][16] . This feature enables spin-controlled local manipulation within one nanoscale coupler, which responds equally to both photonic spin states.We utilize the strong SOI in an achiral plasmonic nanostructure to demonstrate for the first time onchip detection of spin-controlled directional routing in a compact plasmonic nanocircuit. We find that a subwavelength semiring can launch gap surface plasmons supported by seamlessly integrated plasmonic slot waveguides preferentially in one direction, depending on the spin state of locally incident radiation. This spin-dependent phenomenon can thus be regarded as a manifestation ...
Colouration by surface nanostructuring has attracted a great deal of attention by the virtue of making use of environment-friendly recyclable materials and generating non-bleaching colours 1-8 . Recently, it was found possible to delegate the task of colour printing to laser postprocessing that modifies carefully designed and fabricated nanostructures 9,10 . Here we take the next crucial step in the development of structural colour printing by dispensing with preformed nanostructures and using instead near-percolation metal films atop dielectricmetal sandwiches, i.e., near-percolation plasmonic reflector arrays. Scanning rapidly (~ 20 μm/s) across 4-nm-thin island-like gold films supported by 30-nm-thin silica layers atop 100nm-thick gold layers with a strongly focused Ti-sapphire laser beam, while adjusting the average laser power from 1 to 10 mW, we produce bright colours varying from green to red by laser-heating-induced merging and reshaping of gold islands. Selection of strongly heated islands and their reshaping, both originating from the excitation of plasmonic resonances, are strongly influenced by the polarization direction of laser illumination, so that the colours produced are well pronounced only when viewed with the same polarization. Conversely, the laser colour writing with circular polarizations results in bright polarization-independent colour images. The fabrication procedure for near-percolation reflector arrays is exceedingly simple and scalable to mass production, while the laser-induced modification occurs inherently with the subwavelength resolution. This unique combination of remarkable features makes the approach developed for laser colour writing readily amenable for practical implementation and use in diverse applications ranging from nanoscale patterning for security marking to large-scale colour printing for decoration.*e-mail: seib@mci.sdu.dk Ultrafast laser processing of materials holds important implications for both applied and fundamental research 11 , including novel possibilities for post-processing and reconfiguring nanophotonic structures 12,13 . Laser processing at the nanoscale often involves resonant (local) field enhancement and photo-thermal effects, for example, to modify the morphology of individual plasmonic resonators 14 or dielectric nanoparticles (NPs) 10 . Fascinating applications range from the ultrafast delivery of heat at the nanoscale 15 to laser writing of plasmonic colours with subdiffraction-limit resolution 9 . Laser ablation, achieved typically at high radiation fluences, can also be used for colouration of plasmonic surfaces 1 , although with considerably lower spatial resolutions. Previous works on plasmonic colours 2,3 have extensively utilised progress in nanofabrication technologies to accurately pattern surfaces with carefully designed plasmonic nanostructures 4-6 , using also replication techniques oriented towards mass production 7,8 .Considering a very large body of research conducted in the field of structural colours 1-10 , it seems unavoidable...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.