Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XXII

Meta-devices, which are advanced optical elements composed of meta-atoms engineered at the sub-wavelength scale, have garnered significant attention from researchers due to their ability to manipulate the characteristics of incident electromagnetic waves. However, conventional meta-devices, primarily consisting of a single type of meta-atom, suffer from an intrinsic lack of freedom, which in turn restricts their performance and limits their application potential. An integrated resonant unit (IRU) has emerged as a promising solution. It combines multiple meta-atoms, resonant modes, and functionalities into a supercell, can achieve responses and functionalities that exceed those of conventional meta-atoms. This talk will first illustrate the concept of IRUs and then employ two different types of IRUs, plasmonic and dielectric, to demonstrate their ability that break through the phase compensation limitations and improve working efficiency for enhancing achromatic focused beam generation. (Din Ping Tsai's Advanced Photonics review paper on integrated-resonant metadevices is the winner of a 2023 Advanced Photonics EIC’s Choice Award)

While numerous applications of plasmonic metamaterials to sensing and imaging the living matter are well-established, the effects of such photonic structures on the living matter itself are less explored. I will describe the concept of a designer bio-photonic metamaterial that can be used to (a) elicit specific responses from the living cells cultured atop of it, and (b) transduce such responses to optical signals. I will concentrate on several types of three-dimensional mixed-materials metasurfaces comprising plasmonic nano-antennas fabricated atop of tall high aspect ratio dielectric pillars. Cellular dynamics in aqueous environment is probed by illuminating the structures from below through an infrared-transparent substrate and collecting the reflected spectrum. By appropriately choosing the geometry of such elevated nano-antennas, we can induce the cells to wrap around them, thus enhancing the resulting reflected mid-infrared signal. We demonstrate that by increasing the height of the dielectric pillars, the penetration depth of the mid-infrared signal into the cell is also increased.

Investigating the optical response of plasmonic structures requires sub-diffraction limit imaging systems. Photoemission electron microscopy (PEEM) overcomes this limit and allows us to investigate light-matter interactions leading to advances in fundamental research and applications. In PEEM, surface plasmons are excited at the metal dielectric interface by light, and the near-field photoelectron distribution is imaged with <40 nm resolution. A femtosecond tunable wavelength light source in combination with PEEM allows us to perform near-field spectroscopy. Here we design and experimentally demonstrate an optical switch based on the interference of plasmonic modes in whispering gallery mode (WGM) antennas. Varying the wavelength over a short range results in plasmonic modal interference that changes the near-field distribution to be located at opposite side of the antenna. This switching effect could advance applications in minitaturization of optical switching devices, routing in integrated plasmonic nanocircuitry, quantum information processing and biosensing with plasmonic nanosensors.

Two emerging material classes, namely, two-dimensional transition-metal carbides and nitrides (MXenes) and Weyl Semimetals (WSMs) offer exciting opportunities for tailorable photonic devices. The designer-like characteristics of MXenes, achievable with the choice of composition, stoichiometry and surface termination, and tunable properties of single crystalline WSMs, realized through the manipulation of surface conditions, lead to impressive tunability of optical properties in both systems. MXenes exhibit diverse optical properties ranging from plasmonic behavior to dielectric-to-metallic transition as well as strong nonlinear response useful for ultrafast applications. In turn, WSMs such as TaAs show high photocurrent generation and strong second-harmonic generation while WTe2 holds a promise for chiral anomaly applications. The manipulation of linear and nonlinear optical response including the epsilon near zero (ENZ) behavior as well as investigation of hybrid plasmonic-MXene and plasmonic-WSM structures open a broad range of applications for these materials in emerging photonics.

Three-dimensional metamaterial absorbers were applied for ultra-sensitive infrared spectroscopic molecular detection devices. Various types of 3D MIM metamaterial absorbers have been proposed for solid, liquid, and gas samples. Owing to their strong resonant absorption, unwanted background in IR spectroscopy was suppressed, and the signal-to-background ratios has been improved. For gas detection, a 3D co-axial double-cylinder structure is introduced as the unit structure of the metasurface absorber.

Light emission from single emitters, such as organic molecules, quantum dots, or nitrogen vacancies in nanocrystals strongly depends on the electromagnetic environment surrounding the emitter. The interaction of the emitter with strong local electromagnetic fields gives rise to an acceleration of the total decay rate (Purcell effect) which usually results in a broader emission line of the emitter, as well as an energy shift of the emission (Lamb shift). Plasmonic nanoantennas are versatile building blocks which localize light below the diffraction limit thanks to the extremely small effective mode volumes of localized surface plasmons, triggering out the possibility to tailor and exploit both the Purcell factor and the Lamb shift of nearby emitters, even reaching the strong coupling regime with polariton splitting in light emission. We theoretically describe light emission from a variety of nanoantenna-emitter configurations and reveal the potential of plasmonic nanogaps to tailor and engineering the Purcell factor and Lamb shift of light emitted from single nearby emitters, in agreement with experimental evidence.

Metasurfaces are composed of sub-wavelength periodically arranged resonant structures that can manipulate wave-matter interactions in manners not observed in nature. All-optical and all-acoustic metasurfaces have separately demonstrated versatile capabilities such as lensing, beam steering or wavefront control. Here, we study a new class of acoustoplasmonic metasurfaces. By combining the physics of light and sound in previously unexplored ways, this platform enables entirely new avenues to harness the power of wave-matter interactions. This work paves the way toward versatile societal imaging applications ranging from environmental science to biomedical devices or industrial imaging.

High-resolution spatial light modulators are key elements in augmented and virtual reality systems, as well as in advanced LIDAR and angle-dependent sensors as well as advanced imaging systems. Hybrid devices containing liquid crystals, polymers, in combination with plasmonic or dielectric nanoantennas are state of the art. We pursue a different avenue which utilizes conductive polymers, consisting of PEDOT:PSS nanoantennas, who undergo a metal-to-insulator phase transition upon electrical switching in CMOS compatible voltage ranges. In order to reach the required spatial resolution for holograms with high fields of view, we directly pattern PEDOT:PSS by electron beam lithography. This way, 250 nm line widths in metasurface structures have been obtained. By using planar technologies, high-resolution active PEDOT metasurface switching is also attainable. Finally, we are going to demonstrate switching of optical metasurface resonances by a metal-to-insulator transition in inorganic materials.

Hybrid metasurfaces that combine plasmonic metals with dielectrics provide access to both electric and magnetic effects, as well as their combination. This is especially useful when quantum emitters, such as fluorescent molecules, are combined with the metasurface. On the one side, the strong field enhancement provided by the plasmonic metal can be used to excite the molecule, while the dielectric resonator can prevent fluorescence quenching, limit absorption and enhance radiation. In this presentation, we review the design and fabrication of such metasurfaces and characterize experimentally their interaction with fluorescent molecules. We also show how a location-specific position of the emitters can control the overall optical response.

Here, I'll cover two applications of nanophotonic metasurfaces in reflection. Firstly, we propose actively modulating the polarization state of lasing emissions at the source using a metasurface-engaged microcavity. This enhances interactions between light and metasurface atoms, resulting in highly pure and controllable polarized lasing emissions. Secondly, we introduce a compact snapshot hyperspectral imaging system integrating meta-optics and small-data deep learning. Operating in the visible window, our system using a single metasurface chip, demonstrates exceptional fidelity in generating hyperspectral data cubes. This integration promises low-profile advanced instruments for scientific studies and laser physics, bridging the gap between metasurfaces and real-world applications.

We fabricated titanium oxide electrodes with nanocavity functionality and supported gold nanoparticles on them to form a strong coupling between localized surface plasmon resonance (LSPR) mode of the gold nanoparticles and the nanocavity mode. This resulted in successful absorption of a broad range of visible wavelengths. When using the electrodes with modal strong coupling, we observed an increased internal quantum yield of photocurrent generation using water as an electron source compared to plasmonic electrodes without nanocavity. Furthermore, we elucidated that the mechanism behind this enhancement involves quantum coherent interactions of multiple LSPRs via the nanocavity. Here, we report the use of metallic titanium as an adhesion layer between the nanocavity and gold nanoparticles, leading to an increase in electron injection into titanium oxide and provide further insights into the underlying mechanism.

Controlling of light with matter is of great importance for both fundamental science and applications, including control of emission, energy transfer, chemical reactions, resistivity, surface potentials, polaritonic lasers, nanophotonics and many others. We fabricated a series of Kretschmann geometry samples and dye-doped PMMA films, with concentrations of Rhodamine dyes (Rh590 and Rh610) in the polymer (PMMA) ranging between 0 g/L and 1260 g/L and studied their absorption and reflection spectra. The angular and spectral positions of the dips in the experimental reflection spectra resulted in the dispersion curves summarized below. In brief, we have observed (i) multi-branch “staircase” dispersion curves of surface plasmon polaritons at high dye concentrations, (ii) emergence of a new “fork” branch of the dispersion curve, (iii) effect of energy transfer on strong coupling in co-doped donor-acceptor system, and (iv) effect of dye-dye interaction on spectral positions of the absorption bands, explained in terms of the second order perturbation theory.

In this talk, we will highlight our recent work on ultrathin metal films, epsilon-near-zero (ENZ) substrates, and 2D magnetic materials to engineer quantum phenomena. By exploiting ENZ properties, we manipulate quantum emitters' spontaneous emission rates, create radiative energy band gaps for nanoparticles, and utilize the Casimir effect to generate mechanical motion. Further, we show how ultrathin and 2D magnetic materials could allow for quantum levitation through the generation of nanoscale repulsive forces. Our work reveals the potential for novel device architectures harnessing these effects, offering insights into the intricate interplay between ENZ and 2D magnetic materials with quantum photonic phenomena.

Plasmonic lattice resonances are often studied because of their intriguing properties and behavior. Lattice resonances can arise not only from dipole lattices but also from higher-order multipoles, such as quadrupole and octupole configurations. Cross-multipole coupling in a lattice occurs as the interaction between different types of multipole within the lattice structure. We report on the cross-multipolar coupling within the lattice, facilitated by the mismatched refractive indices of the substrate and superstrate, leading to electromagnetic interactions and novel optical phenomena. Theoretically and experimentally, we demonstrate the existence of bound states in the continuum while also revealing quasi-bound states and resonance enhancement in the nanoantenna lattice. We analyze the sensing properties and find that the bound states in the continuum exhibit promising characteristics, particularly in biosensing applications. The periodic arrangement of nanoantennas can enhance the optical response of the nanostructure, facilitating stronger light-matter interaction. Exploring chiral periodic lattices offers a promising route for stronger chiral.

This talk will consider the future of metal halide perovskite (MHP) photovoltaic (PV) technologies as photovoltaic deployment reaches the terawatt scale. The requirements for significantly increasing PV deployment beyond current rates and what the implications are for technologies attempting to meet this challenge will be addressed. In particular how issues of CO2 impacts and sustainability inform near and longer-term research development and deployment goals for MHP enabled PV will be discussed. To facilitate this, an overview of current state of the art results for MHP based single junction, and multi-junctions in all-perovskite or hybrid configurations with other PV technologies will be presented. This will also include examination of performance of MHP-PVs along both efficiency and reliability axes for not only cells but also modules placed in context of the success of technologies that are currently widely deployed.

The recent advent of robust, refractory (having a high melting point and chemical stability at temperatures above 2000°C) photonic materials such as plasmonic ceramics, specifically, transition metal nitrides (TMNs), MXenes and transparent conducting oxides (TCOs) is currently driving the development of durable, compact, chip-compatible devices for sustainable energy, harsh-environment sensing, defense and intelligence, information technology, aerospace, chemical and oil & gas industries. These materials offer high-temperature and chemical stability, great tailorability of their optical properties, strong plasmonic behavior, optical nonlinearities, and high photothermal conversion efficiencies. This lecture will discuss advanced machine-learning-assisted photonic designs, materials optimization, and fabrication approaches for the development of efficient thermophotovoltaic (TPV) systems, lightsail spacecrafts, and high-T sensors utilizing TMN metasurfaces. We also explore the potential of TMNs (titanium nitride, zirconium nitride) and TCOs for switchable photonics, high-harmonic-based XUV generation, refractory metasurfaces for energy conversion, high-power applications, photodynamic therapy and photochemistry/photocatalysis. The development of environmentally-friendly, large-scale fabrication techniques will be discussed, and the emphasis will be put on novel machine-learning-driven design frameworks that leverage the emerging quantum solvers for meta-device optimization and bridge the areas of materials engineering, photonic design, and quantum technologies.

Artificial intelligence (AI) techniques have boosted the capability of optical imaging, sensing, and communication. Concurrently, photonics facilitate the tangible realization of deep neural networks, offering potential benefits in terms of latency, throughput, and energy efficiency. In this talk, I will discuss our efforts in AI photonics with two examples. The first involves employing a convolutional neural network for achieving single-shot full-field measurement of optical signals. The second example pertains to implementing a deep neural network with a multiple-scattering system featuring structural nonlinearity, thereby enabling nonlinear computations using linear optics.

With the proliferation of networked sensors and artificial intelligence, there is an increasing need for edge computing where data is processed at the sensor level to reduce bandwidth and latency while still preserving energy efficiency. In this talk, I will discuss how meta-optics can be used to implement computation for optical edge sensors, serving to off-load computationally expensive convolutional operations from the digital platform, reducing both latency and power consumption. I will discuss how meta-optics can augment, or replace, conventional imaging optics in achieving parallel optical processing across multiple independent channels for identifying, and classifying, both spatial and spectral features of objects.

Plasmonic hot carriers open new opportunities for light energy storage and conversion devices. Using monocrystalline gold, we report unprecedented details on hot-carrier dynamics and photoluminescence emission as well as hot carrier driven chemistry.

I will talk about recent progress in perfect absorbers based on plasmonic metasurface and its applications to incandescent light bulbs, narrow/broad-band infrared emitters, and adaptive radiative cooling. In addition, I will discuss all-dielectric perfect absorber using crystalline silicon and its application to all-optical switching based on degenerate critical coupling of electric and magnetic dipoles in Mie resonators.

The surface of a gateless AlGaN/GaN high-electron-mobility transistor (HEMT) is very sensitive to the attachment of electric charges which can greatly affect its channel conductance. For near two decades, HEMT has been researched as a possible sensor for chemical and bio-spices. In this study, we demonstrate the ability of an AlGaN/GaN HEMT to detect surface plasmon via the plasmonic generated hot-carrier injection. A theoretical model explaining the detecting mechanism will be introduced and verified by several experimental results. We will also discuss several possible applications of HEMT devices in the field of Plasmonics.

Reconfigurable optical devices are key for enhancing optical interconnects, switching, and memory. Achieving high modulation depth with low voltage in the near-infrared (NIR) range remains challenging. This study introduces an electrically switchable device combining Tamm plasmon and PEDOT:PSS, achieving over 88% optical modulation across the NIR range with just ±1 V, compatible with CMOS technology. It works by adjusting charge carrier density through electrochemical doping/dedoping. This device also supports non-volatile multi-memory states, enabling rewritable optical memory and showing neuromorphic behavior, promising for free-space communication and imaging.

We first discuss all-optical modulation with single photons using electron avalanche, resulting in record-high nonlinearities. Then we show that transparent conducting oxides (TCOs) operating in the near-zero index (NZI) regime can provide strong single-cycle modulation, thus enabling novel photonic time crystals.

Transient photonics [1] encompass optical devices that can vanish on demand, after stable operation. In this talk, I will present a platform for transient photonics based on Mg and MgO, materials that dissolve in water at ambient environment [2]. We show vivid color pixels covering a large portion of the sRGB [3] and multi-wavelength absorbers [4], important for applications ranging from encryption to eco-friendly displays. Refs: [1] ACS Photonics 6, 272 (2019). [2] Optical Materials Express 11, 1555 (2021). [3] Adv. Optical Materials 10, 2200159 (2022). [4] ACS Applied Optical Materials 1, 825 (2023).

We will discuss the magneto-optical effects in indium tin oxide (ITO) thin films possessing the epsilon-near-zero (ENZ) wavelength in the telecommunication band. The Faraday rotation angle and the polar Kerr rotation angle of the ITO films are increased at around the corresponding ENZ and EN-one wavelengths, respectively, demonstrating enhanced MO effects in continuous ENZ materials. We also discuss some potential applications of ENZ-MO materials.

I will introduce two very different chalcogenide thin films that exhibit plasmonic or plasmonic-like behaviour in the visible spectrum. The first film is elemental tellurium and we argue that this plasmonic-like behaviour is due to partially delocalised p-orbital electrons that are readily polarized at frequencies in the visible spectrum.The Te films can support surface plasmon polariton-like modes and Te nanodiscs can support local surface plasmon resonances.We believe these results might pave the way for elemental Te-programmable photonics. I will also show how chalcogenide films can be used to grow silver nanoparticles over large areas. In particular, I will show how co-depositing Sb2S3 with Ag results in a perfect absorber material consiting of self-organised nanoresonators. We call this material Black Silver, and we have used it to detect femtomolar concentrations of streptavidin.

Keynote: It is now well understood from works on the topology of light, that complex optical fields (e.g. superoscillatory fields) can be structured at deeply subwavelength scales. Point-like singularities, zones of energy back-flow and strong variations of phase and intensity can be orders of magnitude smaller than the wavelength. As such, scattering of light on nanoscale objects can strongly depend on exactly where the object is actually located in the structured field. This is the foundational idea of metrology with topologically structured light. Moreover, in localization metrology the use of artificial intelligence in the analysis of scattered light allows for instrumental fluctuations and drifts in the whole sample position to be distinguished from the displacements of the nanoscale object with respect to its immediate environment. Furthermore, we demonstrate that ultrafast cameras allow atomic level metrology with a rate of one million measurements per second which gives access to the studies of dynamical processes such as driven or thermal motion in nanostructures.

Efficient optical coupling between propagating light and confined surface polaritons is crucial for nanophotonic device design. However, coupling efficiency diminishes significantly with increased mode confinement due to wavelength mismatch. Despite various proposed mechanisms, achieving flexible and efficient light-to-polariton coupling remains challenging. Our experimental demonstration showcases efficient light-to-surface-plasmon polariton coupling with engineered dipolar scatterers placed optimally from the surface. Gold disks separated by silica spacers from a planar gold surface exhibit perfect coupling conditions, achieved by tuning spacer thickness for a given scatterer geometry resonating at a specific optical frequency. We measure maximum coupling cross section close to the square of light wavelength at optimal distance, facilitated by strong particle-surface interaction and minimal surface-driven particle-dipole quenching, favored at small separations. Our findings, supported by analytical theory and electromagnetic simulations, advocate distant engineered scatterers as a disruptive solution for in/out-coupling challenges in nanophotonics.

By melt-quenching technique, glass samples doped with Sm3+ and containing Ag nanoparticles were synthetized. TEM micrograph and X-ray diffraction patterns are presented. UV–Vis-IR absorption spectra were recorded. Emission spectra of doped samples were collected at room temperature. The results of emission present an enhance with the increasing concentration of Ag nanoparticles due to the plasmon effect causing an enhancement of the electromagnetic field in the vicinity of the metallic nanoparticles, creating a material for photonics and optoelectronic devices.

Linde type A (LTA) zeolite is synthesized in the laboratory using organic templates and different synthetic methods such that the crystal size can be controlled for specific applications. Due to the porous structure, LTA zeolites have attracted significant research attentions in drug delivery system, because of the ability to enhance their loading capacity and evaluate the drug release profile to targeted tissues and organs. This study was to evaluate LTA zeolite synthesized at different temperatures and to monitor their drug loading capabilities.

Optical sensors offer a wide spectrum of subtance detection capabilities, from biological sample diagnostics to hazardous material identification. As a valuble alternative to complex analytical techniques, these sensors ensure rapid results with minimal or no sample preparation, though lacking reusability. By exponsing metal nanoantennas to light at resonant wavelengths, collective oscilations termed localized surface plasmon resonances (LSPR) are induced through the excitation of conduction electrons. Inthis study, we present an innovative optical sensor featuring achieved using electron beam lithography (EBL) to create a 10x10 micron array, with each triangular gold nanoantenna measuring 285.3 nm in height. Analyzing the sensor´s optical properties through Fourier Transformation Infrared Spectroscopy (FTIR), we examined reflectance as a fuction of wavelength to determine resonance wavelengths.

This study proposes an inverse design method that combines an analytical solution for terahertz nanocavities with a double deep Q-learning algorithm. Through this approach, optimization was successfully achieved via the inverse design method, which was not possible with numerical simulation methods. The terahertz nanocavity consists of a loop nanogap array structure, and an ultimate electric field enhancement of more than 30,000 times was experimentally achieved.

This work reports the visualization of ultrafast plasmon as well as its control in nanostructures with nonlinear multi-photon photoemission electron microscopy.

We explore improved plasmonic nanostructure fabrication using process and experiment design methodologies using a DOE and process tracking tool PanMo-Confab. This methodology is shown to yield a robust process window in case of plasmonic nanostructure fabrication and a faster time to optimal design and response variable tuning.

The text highlights the significance of polarized light detection in quantum communication. It introduces polarization-sensitive phototransistors made from MoS2 and Au nanorod arrays, optimized through FDTD calculations. These devices exhibit strong linear polarization selectivity at 660 nm, with a 90.5% polarization ratio. The study suggests exploring efficient polarized-light phototransistors using the proposed nanostructure and discusses potential applications of ultrathin phototransistors with high polarization sensitivity.

Multispectral infrared sensor is a novel technology for detecting infrared, providing simultaneous spectral and spatial information of the target object. However, conventional multispectral infrared sensors face limitations in quantum efficiency due to a low pixel filling ratio. The integration of bandpass filters and sensors poses challenges, including processing difficulty, filter layer thickness, and material constraints. In this work, we present a highly efficient, miniaturized optical filter with a plasmonic filter-based microlens array for a high-efficiency multispectral infrared sensor. Microlens arrays enhance light-gathering efficiency in infrared elements, resulting in high quantum efficiency, while the plasmonic filter, utilizing a 3D post array nanostructure, offers wavelength selectivity. This approach streamlines the integration of micro/nanostructures into infrared imaging sensors, significantly enhancing sensing performance beyond existing methods.

Microdimensional patterning of organic polymers is required for the development of plastic electronics. Traditional top-down lithography is costly economically and wastes a lot of materials. We offer an in-situ patterning approach known as microbubble lithography (MBL) for patterning dispersed organic polymers in micro dimensions. Despite the method's broad use, we chose a model semi-conducting organic plastic (or polymer) called poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a typical organic system for proof of concept. Thus, we create permanent patterns of PEDOT:PSS on glass, which are then investigated using various characterisation techniques like scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and IV properties. We also see conductivity improvements in the patterned polymer without the usage of external doping agents or invasive chemical treatments. These findings present an alternative, more cost-effective, and environmentally friendly method for developing microelectronics devices employing MBL.

Aberration in an optical beam is a common practical issue which affects the quality and shape of the beam and hence important in the light matter interaction. A detailed investigation is carried out on the interaction of the tightly focused beam with a spherical nanoparticle under defocusing. Tightly focused beams with linear and radial polarization are considered for the investigation and the influence of such beam on plasmonic characteristics of a nanoparticle is analyzed. The effect of defocusing is observed on intensity enhancement in near-field in different surrounding media.

The strong coupling enabled plexcitons between plasmons and excitons intrinsically produce distinguishable density of states (DOS) against the Rabi splitting. Taking advantage of this nature dynamic oscillation, we designed the plasmonic nano-cavity filling with monolayered MoS2 and otherwise probe the corresponding Raman scattering. Under the condition of the nearly 1:1 mismatching ratio, we directly observe the weakened Raman scattering, while performing the exciton damping decay, and conversely, the enhanced Raman signal inside the enriched confinement of E-field. We believe, our work provide the deeper understanding of the sensing technology within the strong coupling system, it could highlight the altered nano-device, e.g. the high-speed sensing switch and so on, in the room temperature.

Water confined within nanostructures has been the subject of extensive investigation across various systems, revealing a diminished permittivity under static conditions. However, the exploration of their dynamics, especially in the terahertz (THz) range where hydrogen bond dynamics predominate due to elongated wavelengths, has been largely overlooked. We report the THz complex refractive index of water confined within gold gaps ranging from 2 to 20 nanometers in width. Notably, under stringent confinement conditions, we observed a suppression of long-range correlation dynamics in hydrogen bond networks, particularly within the THz frequency range. This suppression led to a substantial decrease in the terahertz permittivity of water, even in regions not directly interfacing with the confinement surfaces. Insights gained from this platform are instrumental in comprehending the collective dynamics of water molecules over long distances, which are pivotal for elucidating processes like protein folding, formation of lipid rafts, and molecular recognition facilitated by water.

This research evaluates the Silicon loading effect from Deep Reactive Ion Etching (DRIE) on UV-nanoimprint lithography (UV-NIL) in nanofeature patterning, essential for cost-effective, high-resolution lithographic applications as highlighted by the International Technology Roadmap for Semiconductors. Focusing on metasurface structure creation via E-beam lithography (EBL) and Bosch DRIE for a silicon master mold, it examines the influence of etching conditions on structure uniformity and quality. Key findings reveal that the Silicon loading effect, which varies pattern feature depth relative to sizes, significantly impacts nanofeature replication, affecting pattern geometry, quality, and photoresist layer thickness. It causes nonuniform polymer pillar heights and incomplete pattern transfers in UV-NIL, emphasizing the need for etching condition optimization to mitigate these effects for successful nanostructure production on pre-structured substrates. This study underscores the critical role of controlling the loading effect in mastering mold fabrication for efficient pattern replication in UV-NIL metasurface applications.

Nanocones with tapered sidewalls exhibit extraordinary and versatile optical properties such as anti-reflection, super-absorption, and supertransmissivity. We present a single-mask dry etching technique for the fabrication of amorphous silicon oxide nanocones featuring sharp tips, smooth sidewalls, and deterministic distribution onto substrates. We demonstrate high aspect ratio nanocones with sidewalls of constant angle and tip diameters limited mainly by the resolution of electron beam lithography. We further introduce a single-mask, multi-step dry etching approach to fabricate ultra-sharp silicon oxide nanocones with tip diameters as small as 10 nanometers by undercutting nanopillars at mid-height, enabling the etching of multi-height nanocones onto a substrate using a single etch. The presented processes introduce exciting possibilities, including the fabrication of transparent dielectric nanocone distributions onto unconventional films and substrates when fused silica and thermally oxidized silicon are unavailable. The presented findings have applications in nanophotonics and strain engineering of two-dimensional materials.

In this study, a novel hybrid plasmonic waveguide as near field transducer is proposed, consisting of high refractive index nanorod separated from metal by low primitivity region. The design aims to enhance mode confinement at the metal-dielectric interface by combining the benefit of both the nanorod and the plasmonic waveguide.

A samarium doped chalcogenide with chemical composition of Se95Te5Sm0.25 fiber core-based surface plasmon resonance (SPR) has been investigated to detect the Tuberculosis having refractive index in the range of 1.343 to 1.351 RIU. Wavelength interrogation is used for analysis purpose. Sensor is designed using Se95Te5Sm0.25 fiber core- NaF clad, gold (Au), graphene and Tuberculosis sample in the wavelength () range of 400-1400 nm. Sensor design involves optimization of metal layer thickness, incident angle of light, core-clad combination to obtain the high-performance parameter. Transmitted power is calculated considering the n umber of reflections using transfer matrix method (TMM). Performance is analyzed in terms of figure of merit (FOM), sensitivity and detection limit. Results indicate that graphene plays significant role to obtain the significant values of performance parameter. Tuberculosis can be detected sensitivity and FOM of values 4600 nm/RIU and 75 RIU-1 with proposed sensor structure.

We showcase plasmonic metasurfaces employing silicon (Si) nanostructures tailored for deep ultraviolet (DUV) spectroscopy. Si exhibits plasmonic resonance owing to the photon-doping effect originating from interband transitions in the DUV range. Through careful design adjustments, our metasurface achieves strong field enhancement at ~260nm. We investigate potential applications of the reported Si void metasurfaces for surface-enhanced spectroscopy by leveraging the unique properties of our Si metasurface. This study expands the range of materials employed in DUV nanophotonics, unlocking opportunities across diverse fields such as biomedical analysis and nonlinear optics.

Dynamic control over various properties of thermal emission can be achieved through sophisticated engineering of optical states without altering the object's temperature. This presentation introduces our recent study on the dynamic steering of thermal emission using a graphene-based metasurface device. We employ a laterally delocalized Fabry-Perot mode, whose phase condition can be actively tuned by adjusting the graphene's carrier density via electrostatic gating. We experimentally demonstrate that the device can steer thermal emission across a 16-degree range at a wavelength of 6.61 microns, while maintaining high emissivity.

The remarkable turnability with many degrees of freedom of metasurface has allowed for significant advancements in the field of optics. The direction and polarization of photon emission may be adjusted by coupling the geometric plasmonic metasurfaces with the dielectric Si cavity mode. Maintaining the Purcell factor, the hybrid structure with the designed configuration exhibits the highest electric field and best cross-polarization conversion efficiency. Through simulation, the Pancharatnam-Berry (PB) phase structure is effectively used to control the emission wavefront of both chiral and dipole emitters. One key characteristic for sensing applications is the enantiomeric interaction between chiral molecules and circularly polarized light. We use silicon disk metamaterials in conjunction with the P-B phase antenna to provide higher selectivity for real-time chiral sensing. It is also possible to enhance Circular Dichroism (CD) measurement. Experimental demonstration is conducted using L- and D-glucose.

Ultrafast nonlinearity which results in modulation of linear optical response is a basis for development of time-varying media, in particular those operating in the epsilon-near-zero regime. Here, we demonstrate that the intraband excitation of hot electrons in the epsilon-near-zero media results in the strong second-harmonic modification while the changes in linear transmission are negligible. We also show that nonlinear response of anisotropic epsilon-near-zero materials can be controlled by coupling to vibrational modes and influences the polarisation of the reflected light.

Nonlinear optical interactions are of fundamental significance for advanced photonic applications, but often the nonlinearity magnitude is insufficient. In the past decade, we apply laser scanning confocal microscopy, which is a routine tool in biology but unusual with nanomaterials, to inspect single metallic and semiconductor nanostructures. Via the combination of Mie resonance and coupled photothermal/thermo-optic effects, we discovered 1000- to 100000-fold enhanced nonlinear optical indices over bulk materials. The potential applications include all-optical switch and label-free super-resolution microscopy, based on suppression of scattering, saturation (sub-linearity) and reverse saturation (super-linearity). More recently, we uncovered novel light-matter interactions, such as optical bistability in nano-silicon with record-low Q-factor and footprint, as well as displacement resonance. The latter features that linear scattering efficiency is maximal when the focus is misaligned, thus showcasing a significant reduction of nonlinear response threshold, sign flip in all-optical switching, and spatial resolution enhancement.

Transition metal dichalcogenide (TMDC) monolayers are quantum materials with unusual optoelectronic properties. Strongly bound excitons in the material are particularly sensitive to many-body interactions in the atomically thin monolayer, dominating their optical nonlinearity. Hybridization of these excitons with light-like excitations, such as surface plasmon polaritons (SPPs), allows to dramatically alter the optical response and to tailor material properties on the nano scale . The role of excitonic many-body interactions for the new hybridized polariton states is of crucial importance. The ideal tool to investigate these interactions and their coherent dynamics is ultrafast two-dimensional electronic spectroscopy (2DES). Here, we report the first ultrafast 2DES spectra of a TMDC monolayer coupled to plasmonic nanoresonator array. We show that the coupling between excitons and plasmons large enhances the nonlinearity of the hybrid system, exceeding that of the individual exciton and plasmon subsystems by more than an order of magnitude. Our results demonstrate that many-body effects on the two-quantum excitations play a crucial role for this nonlinearity enhancement.

Polaritons are half-wave half-matter particles that emerge in resonant materials strongly coupled to electromagnetic waves. Their responses can provide highly effective tools to engineer light at the nanoscale, enhance nonlinearities and unveil new wave phenomena. Of particular interest is the role that they can play in the context of metamaterials and metasurfaces, as polaritons can provide new knobs to enhance light-matter interactions, and at the same time engineered metastructures can provide new opportunities to engage polaritons and make them useful for applications. In this talk, I will discuss our recent progress in the area of polaritonic metasurfaces, with an emphasis on polaritonics and its role in advancing the field of metamaterials and metasurfaces. Tailored material resonances, based on plasmons, excitons, phonons and/or electronic transitions, can be strongly coupled to electromagnetic waves in engineered metasurfaces, unveiling new degrees of freedom for the control of light-matter interactions, paving the way towards technological advances.

In this invited talk, I will report on our latest advancements in depth sensing technology, leveraging the innovative integration of metasurfaces and photonic crystal surface-emitting lasers (PCSELs). Our methodology facilitates facial recognition within structured light technology and enables monocular depth sensing. Compared to existing approaches, our method projects a higher density of infrared dots across a wider field of view, offering substantial benefits for future spatial computing systems. Notably, our system achieves these advantages in a more compact form factor with reduced power consumption. Additionally, our depth-sensing capabilities operate in real-time at approximately 15 frames per second.

Mid-infrared (MIR) vibrational spectroscopy is a non-invasive and label-free analytical method; thus, it has become an essential technique for examining biological samples and tissues. Research has shown that this method, MIR spectral imaging (MIRSI), can identify various diseases with implications for enhanced biomedical tissue diagnostics. Nonetheless, the diverse chemical makeup of tissues and their spatial heterogeneity, combined with the innately weak interaction between infrared light and biological molecules, limit the efficacy of conventional MIRSI. We introduce a new chemical tissue analysis method that uses plasmonic metasurfaces enabling the detailed molecular mapping of tissue sections. The proposed surface-enhanced chemical imaging method using plasmonic metasurfaces has excellent potential for translational biomedical research and clinical histopathology.

Controlling the physical and electronic properties of materials through optics holds significant appeal for both foundational scientific exploration and the advancement of optoelectronic technologies. A natural progression involves scaling down devices to the nanoscale, necessitating a reduction in the volume of optical interactions to the nanoscale. Optical antennas, though capable of confining light, fall short due to the requirement of illuminating them with a diffraction-limited focal spot, resulting in unintentional illumination of the sample over a larger volume. In contrast, plasmon nanofocusing physically separates the illumination and the nano-light generation sites, enabling background-free and truly confined nano-light. Furthermore, being a non-resonant phenomenon, plasmon nanofocusing is wavelength-independent, allowing for the generation of nano-light across a broad spectrum of wavelengths or even a white nano-light, suitable for nanoscale multi-sensing and optical switching applications. This talk will cover the generation of background-free, wavelength-independent nano-light and its potential applications in nanoscale sensing and optical switching.

Bound States in the Continuum (BIC) refers to a class of exotic states that exist within the continuum energy spectrum but behave as if they were confined or bound. In this study, an electrically wavelength tunable BIC metasurface laser integrated with liquid crystal is demonstrated. The demonstration of this work can be used in various applications, such as optical communications, optical sensing and spatial light modulator device.

Metamaterial absorbers are artificial materials that satisfy optical thicknesses and geometrical thinness simultaneously. By leveraging the characteristics of these metamaterials, we can artificially control the direction of heat flow on spaces or objects. For instance, we demonstrated the ability to generate artificial heat flow across an object or space by controlling the metamaterial arrangement, thereby achieving thermoelectric power generation in a uniform thermal radiation environment. This technology allows us to achieve energy harvesting while simultaneously achieving environmental cooling through non-radiative cooling. Additionally, we introduce the application of this metamaterial thermoelectric conversion technology to optical wireless powering.

This talk explores the transformative power of deep learning (DL) in metasurface-based imaging systems. We will showcase how DL algorithms are pushing the boundaries of performance in different applications, including endo-microscopy, meta-miniscopy, and confocal microscopy. In endo-microscopy, we achieve high-resolution brain images with detailed vasculature within 0.1 seconds (50x faster) by combining DL networks with existing endoscopes. This significantly reduces image acquisition time and system complexity. For DL assisted meta-miniscope, the integration of DL models with a meta-miniscope facilitates the transformation of conventional bright-field images into edge-enhanced images with high contrast accuracy. This novel approach not only enhances image quality but also minimizes system complexity and processing times, thus opening new avenues for improved microscopy techniques. This talk will be of interest to researchers and developers in optics, bioimaging, and deep learning, to highlight significant advancements through metasurfaces with deep learning.

Thermal emission is one of the most fundamental and ubiquitous radiative process, and it is the cornerstone of multiple technologies including heat and energy management, imaging, camouflage, and gas sensing. In our talk, we will discuss how the temporal modulation of the material properties of a macroscopic body introduces a new regime for thermal emission engineering [Vazquez-Lozano & Liberal, Nature Communications, (2023)],[Vazquez-Lozano & Liberal, Optics & Photonics News (2023)]. First, temporal modulation breaks continuous time-translation symmetry, removing the restrictions imposed by energy conservation, and facilitating Superplanckian emission. Similarly, breaking time-reversal symmetry lifts the restrictions imposed by reciprocity, and facilitates emission unconstrained by Kirchhoffs law. Moreover, temporal modulation facilitates the observation of ultra-fast nonequilibrium effects. Finally, temporal modulation mixes semiclassical thermal emission and quantum vacuum amplification effects, thus opening a new regime where the quantum nature of incandescence must be taken into account [Libera,Vazquez-Lozano, Ganfornina-Andrades, arXiv:2401.09897 (2024)]

Metal structures can induce strong light-matter interactions due to their localized near fields. We discuss the chiral and topological properties of the near fields generated by plasmonic metal structures under external excitations. We find that simple metal structures can generate complex configurations of polarization singularities in both the electric and magnetic fields. These singularities carry novel chiral and topological properties that are decided by the genus (number of “holes”) of the metal structures. The results provide new mechanisms for chiral light-matter interactions and new degrees of freedom for light manipulations.

We develop a simple approach for designing high-quality quasi-bound states in the continuum (quasi-BICs) using all-dielectric asymmetry kite-shaped nanopillar arrays and investigated their third-harmonic generation (THG). By manipulating the asymmetric of the kite-shaped meta-atoms, the symmetry-protected quasi-BICs was excited showing a tunable resonant spectral profile between Fano and Lorentzian-lineshapes due to the interplay with the broadband magnetic dipole (MD) mode. The high quality-factor quasi-BICs renders a four order of magnitude THG enhancement in calculation and 46.4-fold THG in experiment. In addition, a hybrid system incorporating amorphous-silicon nanocubes and Indium-Tin-Oxide (ITO) film was developed to study the interplay among electric dipolar, quasi-BICs, and Epsilon-Near-Zero (ENZ) modes. The strong coupling between these resonances results in a Rabi splitting energy of 137 meV and also achieves a broadband THG enhancement in the fundamental wavelength range of 1100 to 1600 nm.

Optical fiber is a well-established and efficient light-guiding medium. Although optical fiber is efficient for transmitting light, its functionality is limited by the dielectric material of the core, which has poor optoelectronic, magneto-optical, and nonlinear-optical responses and has a dielectric diffraction limit. Integration of new materials and nanostructures into fiber will enhance processing/transmission capabilities and novel functionalities. In this talk, I will present our recent development of “Meta”-optical fiber, an advanced optical fiber integrated with emerging nanophotonic concepts such as optical metasurfaces, plasmonic nanowires, and zero-index photonics. I will present the development of ultrathin optical metalens which is cascaded on the facet of a photonic crystal fiber that enables light focusing. I will also discuss the ability to develop tunable meta-optical fiber for advanced beam steering and dynamic focusing. These advanced “meta”-optical fibers open a pathway to revolutionary in-fiber optical imaging/endoscopy, lasers/spectroscopies, and optical communication devices.

Using subdiffracted light from a nanoplasmonic resonator we demonstrate hot-spot nanoheating control of quantum operations at elevated temperatures via temperature-induced shifts of the transition energies of the individual qubits in and out of resonance with the near-field. This introduces a dynamical switch for optical quantum control, significantly elevating solid-state quantum information processing technologies towards higher temperatures.

Harnessing the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals has been the goal of neuroscientists for nearly 50 years. Yet, progress towards that goal remains elusive due to the lack of electro-optic translators that can efficiently convert bioelectronic activity to high photon-count optical signals. In this talk, I will introduce a novel active plasmonic approach for translating tiny electric field oscillations to large optical signals that can be wirelessly detected in the far field. Our nanoscale electrochromically-loaded plasmonic (nano-electro-plasmonic) antenna overcome the fundamental limitations of state-of-art microelectrode array technologies and enable massively multiplexed measurement of electrophysiological signals with single synapse resolution. We recently demonstrated multimillion-plex, high SNR, and subcellular resolution recordings of cell electrogenic activity, reflecting a technical capability well beyond the theoretical limits of state-of-the-art neuroelectrodes well into the 22nd century.

The control of heat at the nanoscale has attracted significant interest over the last decade due to its impact on the function and performance of nanophotonic devices with nanometric footprints. Here, we present a conceptually new approach whereby plasmon resonances in plasmonic nanostructures can be leveraged to create ultrafast nanoscale electric fields, arising from transient thermoelectric effects due to the presence of substantial temperature gradients across the nanostructures. We consider both metallic nanoparticles and nanostructured graphene as suitable platforms to engineer such ultrafast thermoelectric phenomena, and provide designing rules to generate and probe the associated ultrafast electric fields. Our work opens an enticing new direction for understanding photo-electron-phonon interactions and manipulating heat at the nanoscale.

Nanoparticles (NPs) of coinage metals such as Au, Ag, and Cu, have been predominantly researched for their intrinsic exhibition of localized surface plasmon resonance (LSPR) in the visible region. Alloy NPs containing these coinage metals have been used to control the LSPR wavelength, but most of them have face-centered cubic (fcc)-based crystal structures. Recently, we have achieved LSPR in the visible region with intermetallic compound NPs that do not contain coinage metals. The colloidal PtIn2 NPs with a C1 (CaF2-type) crystal structure can be synthesized by the liquid phase method. These NPs show LSPR at wavelengths akin to fcc-Au NPs. These findings dramatically expand the plasmonic nanomaterials library and will contribute to our understanding of the LSPR properties of intermetallic NPs.

Recent strides in plasmonics and nanophotonics have markedly advanced light emission technologies, effectively addressing the "green gap" in LEDs and enhancing UV emissions. Innovations like SiO2 thin film deposition on InGaN/GaN quantum wells and UV irradiation have repaired defects and significantly improved green light efficiency by reducing the quantum-confined Stark effect (QCSE). Similarly, employing surface plasmon resonance (SPR) on semi-polar GaN substrates has boosted internal quantum efficiencies, presenting a solution to the green gap by enhancing photoluminescence. Additionally, SPR-induced photoluminescence enhancement in CdSe/ZnS quantum dots points to potential advancements in RGB display technologies. In UV emission, techniques such as nanostructuring and localized SPR have led to notable enhancements, especially with Ga2O3 and ZnO structures treated with metal films, showcasing the effectiveness of plasmonic effects in emission enhancement. These developments signal significant progress in semiconductor optics, promising more efficient, powerful, and versatile optoelectronic devices for a range of applications, from lighting to advanced displays.

This talk will discuss three routes to realizing nanoscale chiral structures. The first part will discuss controlling circularly polarized photoluminescence from patterned light emitters near plasmonic nanostructures, and how the spatial position of the pattern affects polarization state and photoluminescence intensity. The second part will discuss large-area, scalable, additive patterning techniques for metamaterials that are roll-to-roll compatible. The third will discuss plasmonic structures formed from block copolymer templates, and processing routes that lead to tunable circular dichroism.

Fabrication of large arrays with traditional electron beam lithography techniques is cumbersome during pattern design, usually leads to large data files and easily results in system memory overload. In Dots-on-the-fly patterning, instead of specifying the locations of individual spots, a boundary for the array is given and the spacing between spots within the boundary is specified by the beam step size. A designed pattern element thus becomes a container object, with beam spacing acting as a parameterized location list for an array of spots confined by that container.

A conventional quantum eraser involves physical double slits or virtual paths, such as orbital angular momentum, and has been demonstrated to probe the wave-particle duality of light in the quantum optical regime. Here, we extend the concept of the quantum eraser to holographic applications through a geometric-phase metasurface. In this case, we mark hologram paths with polarization using an entangled photon pair. As a result of a quantum holographic eraser, we demonstrate selective erasure of specific hologram regions with various inserted erasers as a visual manifestation of restoring interference. Our work extends the application of metasurfaces in investigating fundamental concepts, including entanglement, non-locality, and the role of information in quantum optics.

Polaritons in two-dimensional materials are quasiparticles resulting from the strong interaction between photons and specific material excitations. These robust interactions find crucial applications in strong-field physics, facilitating the manipulation of optical excitations and the control of material excitations. This study focuses on two types of polaritons: self-hybridized surface and bulk exciton polaritons in Bi2Se3, WSe2, and two-dimensional Ruddlesden Popper perovskites, as well as in-plane plasmon polaritons in a novel two-dimensional material, namely borophene. Utilizing deep-sub-wavelength cathodoluminescence spectroscopy and all-optical dark-field spectroscopy, our findings reveal that exciton polaritons in WSe2 exhibit a notably short range, while two-dimensional Ruddlesden Popper perovskites support exceptionally long-range exciton polaritons. Furthermore, we investigate borophene excitations in the visible range and demonstrate its capability to host two-dimensional in-plane hyperbolic plasmon polaritons.

Organic-inorganic metal-halide perovskites have gained significant prominence in the fields of photovoltaics, light-emitting devices, and sensors, attributed to their exceptional optical properties and superior semiconductor characteristics. Furthermore, their versatile nature has recently unveiled a new dimension of functionality - piezoelectricity. This intriguing property allows these materials to convert mechanical deformation into an electrical response and vice versa, presenting promising opportunities in diverse applications such as miniaturized self-powered sensors and energy harvesting systems.

In this work, we designed and fabricated high aspect ratio vertical plasmonic nanostructures geared towards gas sensing using infrared absorption. The structures have inner and out Au walls with an aspect ratio of 18.3 and 16.7, respectively. The gap between the walls is partially filled with SiO2. From finite-difference time-domain simulations, we found that the initial resonance frequency of the entire structure is dictated by the overall height of the inner Au walls, while the SiO2/air ratio at the gap can further tune the resonance frequency. This is experimentally demonstrated through the observed Fourier transform infrared measurements.

In this study, we present a novel approach to guiding light within air core fibers by coating the zero-index materials (epsilon-near-zero (ENZ) materials) [16,17] in the inner cladding of hollow core fibers. At the design wavelength of 1550nm, the permittivity of indium tin oxide (ITO) ENZ material approaches zero, enabling the refractive index to dip below 1 in this vicinity. Consequently, total internal reflection can occur within the core of the fiber, facilitating sustained fundamental optical mode with markedly reduced losses compared to uncoated air core fibers. We observe a notable reduction in losses when the ENZ fiber is coupled to its core mode, achieving a maximum improvement of 34dB/cm over the uncoated fiber, particularly near the ENZ wavelength, with a full width at half maximum (FWHM) bandwidth of approximately 550 nm.

When an intense laser interacts with a gas of atoms, high-order harmonics are generated. In the time domain, this radiation forms a train of extremely short light pulses, of the order of 100 attoseconds. Attosecond pulses allow the study of the dynamics of electrons in atoms and molecules, using pump-probe techniques. This presentation will highlight some of the key steps of the field of attosecond science.

The immense potential of metasurfaces is showcased by demonstrating several applications with plasmonic metasurfaces along with their polarization response using Mueller matrix spectroscopy. The work on plasmonic metalenses and holograms with an arbitrary composition of the AuAg alloys shows the successfully fabricated complex nanostructures only by heating nanostructures with a bilayer of Au and Ag of varying thickness at a low temperature of 300°C that retain the shape perfectly. In addition, the spin-orbit photonic effects in a waveguided plasmonic crystal after interacting with structured non-paraxial light via leaky mode excitation is imaged using dark-field Mueller matrix imaging.

We combine the advantages of optical metasurfaces and multimode fiber wavefront shaping to create all-on-fiber devices with actively reconfigurable optical outputs. A spatially-varied arrangement of distinct phase gradient metasurfaces enables the off-axis deflection of focused spots and collimated Gaussian beams to a smoothly-variable angle of up to 70°. Our initial results demonstrate the potential of this device archetype, and show promise for extreme field-of-view enhancement, miniaturization, and multifunctionality for a variety of endoscopic imaging applications.

Optical and acoustic metasurfaces have been extensively studied for wavefront shaping, including lensing, beam steering, and holography. This work aims to explore a new field of acoustoplasmonic metasurfaces that utilize the photoacoustic effect in gold nanoparticles to generate high-frequency acoustic waves via optical excitation. We leverage the extreme polarization-dependence of absorption efficiency in nanoellipsoids to introduce acoustic wavefront tunability, which opens the door to applications in super-resolution acoustic imaging.

Selective modulation of both visible and near-infrared (NIR) radiations are looked for advanced energy efficiency fenestration solutions. Smart windows made of highly doped metal oxides (ITO, AZO, or WO3-x vacancies) are of peculiar interest due to the possible electrochemical modulation of the localized surface plasmon resonance (LSPR) of the associated nanocrystal in the NIR. In this context, oxygen-deficient molybdenum-tungsten hybrid oxides (MoWOx) displaying a very strong LSPR signal astride visible and NIR regions [1] are good candidates for novel electrochromic formulation. The goal of this presentation is twofold: on one hand present two MoWOx formulations compared to their respective parents WOx oxides via comparative TEM, EDX, XRD, XPS and spectroelectrochemical characterizations and on the other hand analyze the plasmonic character of those emerging oxides. For the latter, we thoroughly investigated the use of the Kubelka-Munk formalism in plasmonic configurations. We derived an analytical model respecting all the required hypotheses of the formalism. Our model fully describes the plasmonic properties of metal oxides, consistently with experiments on ITO and MoWOx.

Meta-lenses are advanced flat optical devices composed of artificial nanoantenna arrays. It manipulates the wavefront of light with the advantages of ultrathin, compact, and no spherical aberration. We have developed a series of intelligent machine vision systems with binocular meta-lens for the novel applications of particle image velocimetry (PIV), underwater stereo vision, edge-enhanced depth perception for ill-posed regions, and assisted driving vision. Meta-lens PIV demonstrates a new development trend for the PIV technique for rejuvenating traditional flow diagnostic tools toward a more compact, easy-to-deploy technique. A novel stereo-matching neural network, H-Net, was proposed to derive the disparity information, which incorporates the cross-pixel and cross-view interaction operations. The developed machine vision systems facilitated underwater imaging and assisted driving vision. With binocular meta-lens, multimodal perceptions are provided for machine vision systems in various novel applications.

We experimentally observe for the first time higher-order Kerr optical nonlinearity in epsilon-near-zero (ENZ) transparent conducting oxide thin films when the plasmon-polariton mode near the ENZ regime is excited. Utilizing the z-scan nonlinearity measurement technique, we show that the refractive index exhibits a sign flip upon exiting the ENZ mode at a large angle of incidence. This sign flip stems from the enhanced field intensity within the ENZ film, which results in the 5th-order Kerr nonlinearity making a comparable contribution to the material’s nonlinear refraction. Our findings introduce an additional tuning mechanism for ultrafast optical switching, ultrafast photonics, Kerr lensing, and mode-locking based on ENZ materials.

We show spontaneous symmetry breaking (SSB) in a nonlocal metasurface laser. The system is a hexagonal plasmonic distributed feedback laser that lases at the six K-points in momentum space, or more exactly at the K and K’ modes. A unique properties is that these modes are exactly degenerate in both spatial distribution and energy. By simultaneous real-space and Fourier-space measurements, we map both the relative amplitude (parity symmetry breaking) and phase (rotational symmetry breaking ) of the two symmetry-broken modes. Our results open new perspectives on studying SSB and emergence of spatial coherence in photonic systems.

Photothermal PCR, which exploits the photothermal conversion effect based on the plasmonic absorption resonance of metal nanoparticles, has garnered significant attention for its capacity to enable rapid diagnosis. Through the addition of gold nanoshells, known for their high photothermal conversion efficiency in the near-infrared region, to the PCR mixture, we achieved photothermal quantitative PCR while simultaneously conducting fluorescence measurements during the photothermal PCR cycle. Our photothermal quantitative PCR method expeditiously amplifies Lambda DNA while preserving its detection sensitivity, successfully amplifying the target DNA within just 25 minutes and detecting a minimum of 50 picograms of DNA. Furthermore, we demonstrated the versatility of photothermal quantitative PCR by applying it to genomic DNA extracted from Salmonella, showcasing its effectiveness with long base pairs. By leveraging the photothermal properties of gold nanoshells, our innovative approach to photothermal qPCR will pave the way for point-of-care diagnostics of nucleic acid biomarkers.

Surface lattice resonance (SLR) lasers are promising for optical communication, optical computing, sensing and LiDAR applications. They have previously shown large-area single-mode emission with low threshold as well as tuneable spectral and angular emission using plasmonic nanoparticles embedded in thin film gain media. We demonstrate a novel device architecture with solid-state epitaxial InP gain medium that coupled to a gold nanoparticle array via a thin SiO2 layer. These plasmonic nanoparticles form SLRs that weakly couple to the InP waveguide mode forming a plasmonic-photonic hybrid mode supporting single-mode lasing with low thresholds. We experimentally and theoretically characterise the system. Our devices show no photobleaching. Combining plasmonic SLRs with epitaxial gain media paves the way for large-area on-chip integration of SLR lasers.

Glass matrices doped with rare earths and Cu were synthesized using copper concentration as the control parameter. The amorphous phase of lithium borate was corroborated by X-Ray diffraction (XRD) while size distribution of Nanoparticles was obtained by transmittance electron microscopy (TEM) and crystal phase of Cu nanoparticles was obtained by high resolution transmittance electron microscopy (HRTEM). For photoluminescence, characterizations used were absorbance, photoluminescence emission (PL) and experimental decay times; from the data obtained we performed Judd–Ofelt analysis. With absorbance and PL characterizations in conjunction with CIE 1931, efficiency and shift to white light emission were evaluated. The insights gained from this study have significant implications for future research focused on enhancing the photoluminescence properties of rare earth-doped systems. A comprehensive understanding of the underlying mechanisms behind these phenomena enables us to leverage plasmon effects in similar systems, leading to diverse applications such as color tuning emission.

Manipulation of plasmonic nanostructures with direction control has significant impact in science and engineering applications. We demonstrated the creation of the optical index anisotropy through self-organization of plasmonic gold nanoplates via 3D printing.

A family of samples of lithium borate glass doped with rare earths and containing metallic nanoparticles were synthetized by melt-quenching technique. SEM micrograph is presented. X-ray diffraction patterns of all samples reveal the amorphous structure, which confirms their non-crystalline nature. Physical properties such as density, molar volume and boron-boron separation of amorphous materials are shown. UV–Vis-IR absorption spectra of all samples were recorded and display the characteristic bands of the used rare earths. Emission spectra of doped samples were collected in the temperature range from 30 to 180 Celsius degrees. The results of emission under temperature indicate that the addition of plasmons in glass matrices are responsible for emission stabilization in samples when the temperature is increased.