Plasmonic Sources Research Articles

Sustainable and effective reconditioning of SPR gold chips functionalized with molecularly imprinted polynorepinephrine

Surface Plasmon Resonance (SPR) technology has revolutionized the study of affinity-based biomolecular interactions, offering label-free and real-time analysis capabilities. However, traditional SPR gold chips have been viewed as disposable due to challenges in post-use reconditioning, leading to significant resource wastage and increased costs. To address this issue, we propose a novel approach utilizing polynorepinephrine-based (PNE) Molecularly Imprinted Bio-Polymers (MIBPs) as alternative receptors to conventional antibodies. Self-adhesive MIBPs do not require covalent immobilization. This enables efficient and rapid chip functionalization and post-use removal, facilitating multiple reuses of the plasmon source without compromising analytical performance. We conducted a thorough characterization and data analysis, confirming the robustness and repeatability of a single MIBP-functionalized chip for human IgG detection. 10 cycles of reconditioning and reuse, assayed by 60 kinetic calibrations, were performed. Our findings demonstrate the potential indefinite reuse of SPR chips facilitated by PNE MIBPs, with implications for streamlining test development and routine implementation in SPR biosensing applications. Therefore, they represent a sustainable solution to the longstanding challenge of disposable SPR gold chips also by reducing the reliance on animal-derived Abs for bioanalytic testing. Being also extremely low-cost and green, PNE-based MIBPs minimize the ecological footprint associated with traditional SPR assays. Overall, our work represents a significant advancement towards the development of reusable SPR biosensors. It promises a more sustainable and cost-effective future for biomedical research and diagnostic applications, with application on other transducers and bioanalytical platforms.

Ultrafast photoluminescence and multiscale light amplification in nanoplasmonic cavity glass.

Interactions between plasmons and exciton nanoemitters in plexcitonic systems lead to fast and intense luminescence, desirable in optoelectonic devices, ultrafast optical switches and quantum information science. While luminescence enhancement through exciton-plasmon coupling has thus far been mostly demonstrated in micro- and nanoscale structures, analogous demonstrations in bulk materials have been largely neglected. Here we present a bulk nanocomposite glass doped with cadmium telluride quantum dots (CdTe QDs) and silver nanoparticles, nAg, which act as exciton and plasmon sources, respectively. This glass exhibits ultranarrow, FWHM = 13 nm, and ultrafast, 90 ps, amplified photoluminescence (PL), λem≅503 nm, at room temperature under continuous-wave excitation, λexc = 405 nm. Numerical simulations confirm that the observed improvement in emission is a result of a multiscale light enhancement owing to the ensemble of QD-populated plasmonic nanocavities in the material. Power-dependent measurements indicate that >100 mW coherent light amplification occurs. These types of bulk plasmon-exciton composites could be designed comprising a plethora of components/functionalities, including emitters (QDs, rare earth and transition metal ions) and nanoplasmonic elements (Ag/Au/TCO, spherical/anisotropic/miscellaneous), to achieve targeted applications.

Diamond for High-Power, High-Frequency, and Terahertz Plasma Wave Electronics.

High thermal conductivity and a high breakdown field make diamond a promising candidate for high-power and high-temperature semiconductor devices. Diamond also has a higher radiation hardness than silicon. Recent studies show that diamond has exceptionally large electron and hole momentum relaxation times, facilitating compact THz and sub-THz plasmonic sources and detectors working at room temperature and elevated temperatures. The plasmonic resonance quality factor in diamond TeraFETs could be larger than unity for the 240-600 GHz atmospheric window, which could make them viable for 6G communications applications. This paper reviews the potential and challenges of diamond technology, showing that diamond might augment silicon for high-power and high-frequency compact devices with special advantages for extreme environments and high-frequency applications.

Actively tuning anisotropic light–matter interaction in biaxial hyperbolic material α-MoO3 using phase change material VO2 and graphene

Anisotropic hyperbolic phonon polaritons (PhPs) in natural biaxial hyperbolic material α-MoO3 has opened up new avenues for mid-infrared nanophotonics, while active tunability of α-MoO3 PhPs is still an urgent problem necessarily to be solved. In this study, we present a theoretical demonstration of actively tuning α-MoO3 PhPs using phase change material VO2 and graphene. It is observed that α-MoO3 PhPs are greatly dependent on the propagation plane angle of PhPs. The insulator-to-metal phase transition of VO2 has a significant effect on the hybridization PhPs of the α-MoO3/VO2 structure and allows to obtain actively tunable α-MoO3 PhPs, which is especially obvious when the propagation plane angle of PhPs is 90°. Moreover, when graphene surface plasmon sources are placed at the top or bottom of α-MoO3 in α-MoO3/VO2 structure, tunable coupled hyperbolic plasmon–phonon polaritons inside its Reststrahlen bands (RBs) and surface plasmon–phonon polaritons outside its RBs can be achieved. In addition, the above-mentioned α-MoO3-based structures also lead to actively tunable anisotropic spontaneous emission (SE) enhancement. This study may be beneficial for realization of active tunability of both PhPs and SE of α-MoO3, and facilitate a deeper understanding of the mechanisms of anisotropic light–matter interaction in α-MoO3 using functional materials.

Advancements in nanoscale coherent emitters: The development of substrate-free surface plasmon nanolasers

The surface plasmon effect can be used to confine electromagnetic fields to a small footprint measuring tens of nanometers. The resultant resonant cavities function as optimal coherent light sources with subwavelength scale configurations. The plasmonic laser sources based on nanoshell structures, in particular, have demonstrated the potential for use in the detection of subcellular mesoscopic molecular structures. However, this structure has a high plasmon dephasing rate, which can increase the threshold of the device, making it difficult to achieve electrically excited structures, thereby rendering them unsuitable as an active component for integration into optoelectronic circuits. A different approach to confining electromagnetic fields involves using a propagating surface plasmon laser structured on a planar layered semiconductor–insulator–metal. This design enables the surface plasmon to propagate along the direction of the nanowire and offers the potential to achieve electrically driven structures by injecting current into the semiconductor nanowire. Consequently, this structure is more effective in guiding energy into integrated optoelectronic circuits compared to the isotropic radiation of nanoshell structures. However, this design also necessitates a supporting substrate, resulting in the actual device volume exceeding the nanoscale and, in some cases, even larger than the size of a cell. This limitation hinders the application of integrated optoelectronic circuits at the micro/nanoscale for bio-applications. To address these challenges, we developed a substrate-free surface plasmon polariton laser. We demonstrated that allowing direct contact between the film and the air significantly reduced the laser threshold. Furthermore, the device maintained its operational capability across different surfaces.

Photothermally heated colloidal synthesis of nanoparticles driven by silica-encapsulated plasmonic heat sources

Using photons to drive chemical reactions has become an increasingly important field of chemistry. Plasmonic materials can provide a means to introduce the energy necessary for nucleation and growth of nanoparticles by efficiently converting visible and infrared light to heat. Moreover, the formation of crystalline nanoparticles has yet to be included in the extensive list of plasmonic photothermal processes. Herein, we establish a light-assisted colloidal synthesis of iron oxide, silver, and palladium nanoparticles by utilizing silica-encapsulated gold bipyramids as plasmonic heat sources. Our work shows that the silica surface chemistry and localized thermal hotspot generated by the plasmonic nanoparticles play crucial roles in the formation mechanism, enabling nucleation and growth at temperatures considerably lower than conventional heating. Additionally, the photothermal method is extended to anisotropic geometries and can be applied to obtain intricate assemblies inaccessible otherwise. This study enables photothermally heated nanoparticle synthesis in solution through the plasmonic effect and demonstrates the potential of this methodology.

TiO2‐Based Hybrid Nanoscale Light Source

AbstractThe titanium dioxide nanosphere (TiO2 NS) is a moderate refractive index (MRI) nanostructure which can support Mie resonances such as magnetic dipole resonance (MDR), electric dipole resonance (EDR), etc. However, TiO2 is a wide indirect band gap (3.2 eV) semiconductor, and TiO2 NSs cannot be excited to emit luminescence by near‐infrared (NIR, 770 nm–800 nm) femtosecond (fs) lasers. In this paper, a MDR‐induced nanoscale plasmon source is conceived to provide a large number of hot electrons, which can be used to light up TiO2 NSs. The effect of different metals (Titanium‐Ti, Palladium‐Pd, Gold‐Au) as the MDR‐induced nanoscale plasmon sources on the optical response of TiO2‐based hybrid NSs is studied. This work provides a new strategy for the application of TiO2‐based hybrid NSs as integrated efficient nanoscale white light sources.

Efficient and Unidirectional Launching of Surface Plasmons from a Hyperbolic Meta‐Antenna

AbstractTunnel nanojunctions associated with inelastic electron tunneling have demonstrated crucial applications in on‐chip photonic and plasmonic circuitries due to their high photon modulation speed, large‐scale integration capability, and working‐wavelengths range tunability. However, because most electrons tunnel through a junction elastically, the external quantum efficiency of a nanojunction‐based plasmonic source tends to be around 10−4, severely limiting their applications to date. In this work, an integrated high‐efficiency unidirectional plasmonic source composed of an edge‐to‐edge thickness gradient hyperbolic meta‐antenna is proposed. By engineering the extra wavevector dimension, this study demonstrates a theoretical external quantum efficiency of up to 23% for this system. This is attributed to the large local density of optical states from hyperbolic dispersion and wavevector‐match conditions provided by the optical antennas. Furthermore, this study also demonstrates the tunability of this system across a range of wavelengths from 1300 to 1700 nm. The implementations of these metamaterial‐based tunneling structures enable fast and tunable on‐chip high‐efficiency sources for applications in high‐performance plasmonic circuitries.

Acousto‐Plasmo‐Magnonics: Coupling Spin Waves with Hybridized Phonon‐Plasmon Waves in a 2D Artificial Magnonic Crystal Deposited on a Plasmonic Material

AbstractCoupling between spin waves (SWs) and other waves in nanostructured media has emerged as an important topic of research because of the rich physics and the potential for disruptive technologies. Herein, a new phenomenon is reported in this family involving coupling between SWs and hybridized phonon‐plasmon waves in a 2D periodic array of magnetostrictive nanomagnets deposited on a silicon substrate with an intervening thin film of aluminium that acts as a source of surface plasmons. Hybridized phonon‐plasmon waves naturally form in this composite material when exposed to ultrashort laser pulses and they non‐linearly couple with SWs to produce a new breed of waves – acousto‐plasmo‐spin waves that can exhibit a “frequency comb” spanning more than one octave. This phenomenon, that we call acousto‐plasmo‐magnonics resulting from tripartite coupling of magnons, phonons and plasmons, is studied with time‐resolved magneto‐optical‐Kerr‐effect microscopy. The findings also reveal the presence of parametric amplification in this system; energy is transferred from the hybridized phonon‐plasmon modes to the acousto‐plasmo‐spin wave modes to amplify the latter. This opens a path to design novel active metamaterials with tailored and enhanced response. It may enable high‐efficiency magneto‐mechanical‐plasmonic frequency mixing in the GHz−THz frequency regime and provide a unique avenue to study non‐linear coupling, parametric amplification, and frequency comb physics.

Femtosecond Laser-Printed Gold Nanoantennas for Electrically Driven and Bias-Tuned Nanoscale Light Sources Operating in Visible and Infrared Spectral Ranges.

Nanoscale electrically driven light-emitting sources with tunable wavelength represent a milestone for implementation of integrated optoelectronic chips. Plasmonic nanoantennas exhibiting an enhanced local density of optical states (LDOS) and strong Purcell effect hold promise for fabrication of bright nanoscale light emitters. Here, we justify gold parabola-shaped nanobumps and their ordered arrays produced by direct ablation-free femtosecond laser printing as broadband plasmonic light sources electrically excited by a probe of scanning tunneling microscope (STM). I-V curves of the probe-nanoantenna tunnel junction reveal characteristic bias voltages correlating with visible-range localized (0.55 and 0.85 μm) and near-IR (1.65 and 1.87 μm) collective plasmonic modes of these nanoantennas. These multiband resonances confirmed by optical spectroscopy and full-wave simulations provide enhanced LDOS for efficient electrically driven and bias-tuned light emission. Additionally, our studies confirm remarkable applicability of STM for accurate study of optical modes supported by the plasmonic nanoantennas at nanoscale spatial resolution.

Role of optical rectification in photon-assisted tunneling current

Emission of light and conversely rectification of an optical signal using an all-metallic electronic device is of fundamental and technological importance for nano-optics. However despite recent experimental efforts in the development of electrically-driven plasmonic sources, the interplay between quantum transport and optics is still under debate. Here, we measure the photon-assisted current in a planar tunnel junction under infrared illumination. To address the microscopic mechanism at the origin of the optical rectification, we compare the photon-assisted current and the current-voltage characteristic of the junction measured on a voltage range much greater than {V}_{0}=frac{hc}{elambda }=0.825,{{{{{{{rm{V}}}}}}}}, previously unexplored. The experimental results do not agree with the theory based on the existence of a non-thermal distribution function corresponding to the exchange of energy quanta between electrons and photons. We show instead that the illumination power mainly goes into heating and that the rectification results from the tunneling Seebeck effect.

Accelerated pyro-catalytic hydrogen production enabled by plasmonic local heating of Au on pyroelectric BaTiO3 nanoparticles

The greatest challenge that limits the application of pyro-catalytic materials is the lack of highly frequent thermal cycling due to the enormous heat capacity of ambient environment, resulting in low pyro-catalytic efficiency. Here, we introduce localized plasmonic heat sources to rapidly yet efficiently heat up pyro-catalytic material itself without wasting energy to raise the surrounding temperature, triggering a significantly expedited pyro-catalytic reaction and enabling multiple pyro-catalytic cycling per unit time. In our work, plasmonic metal/pyro-catalyst composite is fabricated by in situ grown gold nanoparticles on three-dimensional structured coral-like BaTiO3 nanoparticles, which achieves a high hydrogen production rate of 133.1 ± 4.4 μmol·g−1·h−1 under pulsed laser irradiation. We also use theoretical analysis to study the effect of plasmonic local heating on pyro-catalysis. The synergy between plasmonic local heating and pyro-catalysis will bring new opportunities in pyro-catalysis for pollutant treatment, clean energy production, and biological applications.

Nanoheating and Nanoconduction with Near‐Field Plasmonics: Prospects for Harnessing the Moiré and Seebeck Effects in Ultrathin Films

AbstractNear‐field plasmonics is a burgeoning field that has unlocked several opportunities related to quantum information processing, single‐molecule spectroscopy, and cavity quantum electrodynamics. All of which require the adept control of light, heat, and charges on the nanoscale. In particular, nanoresonators and near‐field transducers (NFTs) have the ability to subdiffract light well below the classical diffraction limit by coupling a photon mode to a plasmonic mode. Herein, advantage is taken of a nanoscale plasmonic light source produced by an NFT and the subsequent “hot spot” created by its relatively high intensity. It is theoretically demonstrated how the light, heat, and current produced can be manipulated when incident on layers of black phosphorous (BP), a highly abundant material with electric and thermal conductivity values comparable to graphene. Moiré physics of two films rotated relative to one another, along with the Seebeck effect for which temperature gradients show the possibility to induce electrical voltages (milli‐Volts) without a metallic contact, is specifically investigated. It is found that these methods can effectively regulate the temperature distribution and its values by roughly 101–102 K, crucial to the functionality of many nanodevices, and furthermore manipulate the directional flow of current; advantageous for electrical switching and output steering of energy.

Spatial Control over Stable Light‐Emission from AC‐Driven CMOS‐Compatible Quantum Mechanical Tunnel Junctions

AbstractThe potential application of quantum mechanical tunnel junctions as subdiffraction light or surface plasmon sources has been explored for decades, but it has been challenging to create devices with subwavelength spatial control over the light or plasmon excitation. This paper describes spatial control over the electrical excitation of surface‐plasmon polaritons (SPPs) and photons in large‐area junctions of the form of Al–AlOX–Cu complementary metal‐oxide‐semiconductor (CMOS)‐compatible tunnel junctions. Nanoscale spatial control (smallest feature sizes of 150 nm) is achieved by locally fine‐tuning the thickness of the AlOX tunneling barrier resulting in large local tunneling currents and associated SPP excitation rates. Mostly, plasmonic tunnel junctions are studied under DC operation with a relatively large bias (and associated currents) to observe light emission at optical frequencies. Large voltages risk device failure and reduce device lifetimes. Here it is demonstrated that the operational lifetime of AC‐driven plasmonic tunnel junctions is improved by a factor of three. Under DC conditions, slow processes that lead to device failure (e.g., undesirable electromigration leading to shorts) readily occur, thus limiting the device decay time to 9.2 h; but under AC operation, such processes are slow with respect to the voltage changes prolonging the decay time beyond 18.0 h.

Role of Gain in Fabry–Pérot Surface Plasmon Polariton Lasers

Plasmonic lasers generate strongly confined electromagnetic fields over a narrow range of wavelengths. This is potentially useful for enhancing nonlinear effects, sensing chemical species, and providing on-chip sources of plasmons. By placing a semiconductor gain layer near a metallic interface with a gap layer in between, plasmonic lasers have been demonstrated. However, the role of gain in this common design has been understudied, leading to suboptimal choices. Here, we examine planar metallic lasers and explore the effect of gain on the lasing behavior. We print semiconductor nanoplatelets as a gain layer of controllable thickness onto alumina-coated silver films with integrated planar Fabry–Pérot cavities. Lasing behavior is then monitored with spectrally and polarization-resolved far-field imaging. The results are compared with a theoretical waveguide model and a rate-equation model, which consider both plasmonic and photonic modes and explicitly include losses and gain. We find that the nature of the lasing mode is dictated by the gain-layer thickness and, contrary to conventional wisdom, a gap layer with a high refractive index can be advantageous for plasmonic lasing in planar Fabry–Pérot cavities. Our rate-equation model also reveals a regime where plasmonic and photonic modes compete in an unintuitive way, potentially useful for facile, active mode switching. These results can guide future design of metallic lasers and could lead to on-chip lasers with controlled photonic and plasmonic output.

Correction to: Exploiting hyperbolic metamaterial as a substrate for graphene surface plasmonic Cherenkov THz radiation source

Correction to: Exploiting hyperbolic metamaterial as a substrate for graphene surface plasmonic Cherenkov THz radiation source

Plasmon-Enhanced Nitrogen Vacancy-Rich Carbon Nitride Electrochemiluminescence Aptasensor for Highly Sensitive Detection of miRNA.

The development of biosensors for biologically important substances with ultralow content such as microRNA is of great significance. Herein, a novel surface plasmon-enhanced electrogenerated chemiluminescence-based aptasensor was developed for ultrasensitive sensing of microRNA by using nitrogen vacancy-rich carbon nitride nanosheets as effective luminophores and gold nanoparticles as plasmonic sources. The introduction of nitrogen vacancies improved the electrochemiluminescence behavior due to improved conductance and electrogenerated chemiluminescence activity. The introduction of plasmonic gold nanoparticles increased the electrochemiluminescence signal intensity by more than eightfold. The developed surface plasmon-enhanced electrogenerated chemiluminescence aptasensor exhibited good selectivity, ultrasensitivity, excellent stability, and reproducibility for the determination of microRNA-133a, with a dynamic linear range of 1 aM to 100 pM and a limit of detection about 0.87 aM. Moreover, the surface plasmon-enhanced electrogenerated chemiluminescence sensor obtained a good recovery when detecting the content of microRNA in actual serum.

Large angle scattering at metallized interface of indium-tin-oxide-coated Er, Fe co-doped LiNbO3, and its impact on upconversion emissions

We demonstrated that visible surface plasmon polaritons (SPPs) were excited at the metallized interface of indium-tin-oxide (ITO)-coated iron doped Y-cut and Z-cut lithium niobate (Fe : LiNbO3, Fe:LN) slabs, where large angle scattering and light tracks were observed on the surface. After introducing active erbium element, it was found that SPPs’ excitation could greatly affect upconversion emission (UCE) in Er,Fe:LN crystal samples. This surface effect was more attractive when increasing the surface-to-volume ratio with powdered form. In the ITO-coated Er,Fe:LN specimen, dynamic variations of huge UCE dropping-down and gradual rising were observed, which is a result of energy loss via coupling to SPPs. Our work supports an opportunity in designing plasmonic nanometric light sources, leading paths toward implementing spasers apart from lossy metals in photonic waveguides.

Controlled Coherence Plasmonic Light Sources

Through a computational model, we study the coherence converting capabilities of an array of holes in a surface plasmon-supporting metal plate, with an eye towards the creation of controlled coherence plasmonic light sources. We evaluate how the average coherence and transmission of the hole array depends on the parameters of the array, such as the array geometry, lattice constant, and hole size. We show that the location of coherence bandgaps and resonances can be estimated through a simple formula and that increases in coherence are strongly correlated with increases in transmission.

Electrostatically Tunable Near‐Infrared Plasmonic Resonances in Solution‐Processed Atomically Thin NbSe2

AbstractIn the broad spectral range, near‐infrared (NIR) plasmonics find applications in telecommunication, energy harvesting, sensing, and more, all of which would benefit from an electrostatically controllable NIR plasmon source. However, it is difficult to control bulk NIR plasmonics directly with electrostatics because of the strong electric‐field screening effect and high carrier concentration required to support NIR plasmons. Here, this constraint is overcome and the observation of NIR plasmonic resonances that can be modulated electrostatically over a range of ≈360 cm–1 in few‐layer NbSe2 gratings is reported, thanks to the enhanced electrostatics of atomically thin 2D materials and the high‐quality film produced by a solution method. NbSe2 plasmons also render strong field confinement due to their atomic thickness and provide an extra degree of resonance frequency modulation from the layered structure. This study identifies metallic 2D materials as promising (easily produced and well‐performing) candidates to extend electrostatically tunable plasmonics to the technologically important NIR range.