Plasmon-induced Absorption Research Articles

Dynamically tunable highly sensitive sensor based on graphene and black phosphorus composite metamaterial

Focusing on the realization of multiple-detection-point sensors in the mid-infrared band, a dynamically tunable high-sensitive index refraction sensor based on graphene and black phosphorus (BP) composite metamaterial is proposed. By adjusting the height of the grating, the strength of the structural plasmon-induced absorption (PIA) can be enhanced within a certain range. The energy transfer mechanism of the system is analyzed by the coupled mode theory (CMT), the theoretical data of CMT fit well with the FDTD simulation results, which proves that the analysis of the system using the CMT model is correct. The resonant wavelengths of the PIA can be efficiently modulated by changing the Fermi level of graphene and the carrier density of BP. It is worth mentioning that under different environmental refractive indexes, our proposed system has excellent sensing characteristics in the mid-infrared band. The maximum sensitivity and the maximum figure of merit (FOM) are up to 5.174 μm/RIU and 26.449, respectively. This research could play an important role in mid-infrared optical sensors.

Synergistic enhancement of plasmon induced photocatalytic and photoelectrochemical performance on ZnWO4/Ag2O@Ag hybrid-heterostructures

A novel hybrid photocatalyst, ZnWO4/Ag2O@Ag heterostructure was synthesized using a simple one-pot microwave treatment with varying concentrations of silver. Physico-chemical characterization was performed to elucidate the synthesized nanohybrids' properties. The photocatalytic activity of both pristine and heterostructure samples was evaluated through the degradation of cationic MB dye. Among the varied Ag concentrations, the 9 % Ag-doped ZnWO4/Ag2O heterostructure exhibited superior degradation performance, with a degradation rate of 93 % achieved within 45 min, surpassing both other Ag concentrations (89 % (90 min) for 1 % Ag, 87 % (80 min) for 3 % Ag, 90 % (80 min) for 5 % Ag and 91 % (45 min) for 7 % Ag) and pristine ZnWO4 (91 % (90 min)) samples. This catalytic enhancement can be attributed to the formation of heterostructures, plasmon-induced absorption enhancement within specific wavelength ranges, and reduced charge recombination rates. UV–visible studies revealed Ag nanoparticles of various sizes in the heterostructures, supported by surface plasmon resonance (SPR) peaks at 480 and 550 nm, respectively. Trapping experiments indicated that •OH and •O2− were the active species in MB reduction for pure and heterostructure samples. Furthermore, the hybrid heterostructure samples exhibited high stability and reusability in photocatalytic degradation. These findings suggest that the ZnWO4/Ag2O heterostructure photocatalysts are promising candidates for environmental remediation applications.

Gas concentration and refractive index sensor based on plasmonic induced absorption in metal-insulator-metal waveguide coupled with arc resonators structure

In this paper, the plasmonic induced absorption (PIA) effect is numerically studied in a plasmonic metal-insulator-metal (MIM) waveguide coupled with disk and arc-shaped resonators. The PIA spectrum characteristics and magnetic field distributions are investigated by the Finite difference-time domain method (FDTD) method, the PIA effect originated from the coupling of two resonance modes excited by the disk resonator and the arc-shaped resonator. The coupling mode theory (CMT) is used to fit the PIA transmission spectrum, and the calculated result fits well with the simulated spectrum. A double PIA spectrum can be observed by introducing another arc-shaped resonator both on the same or the opposite side. Three different structures are designed to achieve the PIA effect, and we found the PIA response can be easily tuned by altering the structure’s parameters. Three structures are designed and compared, the PIA spectra exhibit high refractive index (RI) sensing with maximum sensitivity of 867.2nmRIU−1. Besides, the proposed structure can also be used as a gas concentration (GC) sensor when the polyhexamethylene biguanide (PHMB) is introduced, a maximum sensitivity of 142.1 pm/ppm is achieved for the proposed structure II, the maximum figure of merit (FOM) and Q value are 57.8 and 65.9, respectively. Therefore, the results represented in this paper will be beneficial in the fields of high-performance refractive index and gas sensors.

Dynamically tunable multi-band plasmon-induced absorption based on multi-layer borophene ribbon gratings.

In this paper, we propose a borophene-based grating structure (BBGS) to realize multi-band plasmon-induced absorption. The coupling of two resonance modes excited by upper borophene grating (UBG) and lower borophene grating (LBG) leads to plasmon-induced absorption. The coupled-mode theory (CMT) is utilized to fit the absorption spectrum. The simulated spectrum fits well with the calculated result. We found the absorption peaks exhibit a blue shift with an increase in the carrier density of borophene grating. Further, as the coupling distance D increases, the first absorption peak shows a blue shift, while the second absorption peak exhibits a red shift, leading to a smaller reflection window. Moreover, the enhancement absorption effect caused by the bottom PEC layer is also analyzed. On this basis, using a three-layer borophene grating structure, we designed a three-band perfect absorber with intensities of 99.83%, 99.45%, and 99.96% in the near-infrared region. The effect of polarization angle and relaxation time on the absorption spectra is studied in detail. Although several plasmon-induced absorption based on two-dimensional (2D) materials, such as graphene, black phosphorus, and transition metal dichalcogenides (TMDs), have been previously reported, this paper proposes a borophene-based metamaterial to achieve plasmon-induced perfect absorption since borophene has some advantages such as high surface-to-volume ratios, mechanical compliance, high carrier mobility, excellent flexibility, and long-term stability. Therefore, the proposed borophene-based metamaterial will be beneficial in the fields of multi-band perfect absorber in the near future.

Perfect absorption frequency modulation, optical switching and slow-light multifunctional integrated device based on plasmon-induced absorption

Perfect absorption frequency modulation, optical switching and slow-light multifunctional integrated device based on plasmon-induced absorption

Controlled plasmon-induced nonlinear absorption and optical limiting in Al/PVP composite nanofibers.

The effect of aluminum (Al) concentration on the surface plasmon resonance (SPR) band position of aluminum/polyvinylpyrrolidone (Al/PVP) composite nanofibers was investigated to strengthen nonlinear absorption (NLA) and widen its spectral range. With increasing Al content in PVP nanofibers, the SPR band was shifted towards excitation wavelength and an improved NLA response was achieved. The NLA response was examined both experimentally, by conducting Z-scan experiments, and theoretically, using two models. In the first model, the contributions of one-photon absorption (OPA), two-photon absorption (TPA), excited state absorption (ESA) and saturated absorption (SA) are considered. The second model, on the other hand, is a model that is widely used in the literature, and while taking into account the contributions of OPA and TPA, it neglects the ESA. The first model provides more accurate results due to the high concentration of free carriers in the samples examined. In order to reveal the contribution of Al to the nonlinear absorption, a laser excitation wavelength of 532 nm was chosen to minimize both the defect-assisted sequential and genuine two-photon absorption contributions of PVP. While the nonlinear absorption of pure PVP is quite weak, the NLA performance of Al/PVP nanofibers significantly improved as the Al content increased. As the amount of Al increased, the aggregation effect increased and a broadening and red shift in the SPR band were observed in the plasmonic behavior. This indicates a decreasing interparticle distance in Al particles. The sample with the highest amount of Al is anticipated as a potential candidate for optical limiting (OL) applications due to its superior NLA performance and SPR band furthest towards the near infrared (NIR) region, allowing a wider range of wavelength set to be used in OL applications.

Double Narrowband Induced Perfect Absorption Photonic Sensor Based on Graphene–Dielectric–Gold Hybrid Metamaterial

Double narrowband induced perfect absorption in the terahertz region is achieved in a graphene–dielectric–gold hybrid metamaterial, whose physical mechanism is analyzed using the coupled-mode theory (CMT), which agreed well with the finite-difference time-domain (FDTD) simulation. This study found that the Fermi level of graphene can be adjusted to improve the absorptivity when the refractive index (RI) nd of the chosen dielectric cannot achieve a good absorption effect. In addition, the blue shift of absorption spectrum can be used in the design of dual-frequency electro-optical switches, of which the modulation degree of amplitude (MDA) can reach as high as 94.05% and 93.41%, indicating that this is a very promising electro-optical switch. Most significantly, the RI sensing performance is investigated, which shows an ultra-high absorption sensitivity SA = 4.4°/RIU, wavelength sensitivity Sλ = 9.8°/RIU, and phase shift sensitivity Sφ = 2691°/RIU. At last, an interesting finding is that the two peaks (R1 and R2) of plasmon-induced absorption (PIA) show different polarization characteristics (insensitive or sensitive) to the incident light angle; this polarization-sensitive is particularly important for the PIT/PIA-based optical polarizers. Undoubtedly, this paper is of great significance to the research and design of terahertz photonic devices and sensors.

Analogous plasmon-induced absorption based on an end-coupled MDM structure with area-cost-free cavities.

We theoretically investigate an end-coupled metal-dielectric-metal (MDM) structure that achieves analogous plasmon-induced absorption (APIA) in an area-cost-free manner. First, a squared ring is set to end-couple with MDM input and output waveguides, generating three Lorentzian-like peaks in the spectrum. Then, two APIA windows as well as two Fano resonances can be induced via appropriately arranging two area-free cavities. Numerous numerical results demonstrate that the proposed structure has remarkable sensing and phase characteristics. Our proposed PIA-based MDM structure is promising in potential applications of bio-chemical sensing, slow light devices, optical switching, and chip-scale plasmonic devices.

Improving Photostability of Photosystem I-Based Nanodevice by Plasmonic Interactions with Planar Silver Nanostructures.

One of the crucial challenges for science is the development of alternative pollution-free and renewable energy sources. One of the most promising inexhaustible sources of energy is solar energy, and in this field, solar fuel cells employing naturally evolved solar energy converting biocomplexes—photosynthetic reaction centers, such as photosystem I—are of growing interest due to their highly efficient photo-powered operation, resulting in the production of chemical potential, enabling synthesis of simple fuels. However, application of the biomolecules in such a context is strongly limited by the progressing photobleaching thereof during illumination. In the current work, we investigated the excitation wavelength dependence of the photosystem I photodamage dynamics. Moreover, we aimed to correlate the PSI–LHCI photostability dependence on the excitation wavelength with significant (ca. 50-fold) plasmonic enhancement of fluorescence due to the utilization of planar metallic nanostructure as a substrate. Finally, we present a rational approach for the significant improvement in the photostability of PSI in anoxic conditions. We find that photobleaching rates for 5 min long blue excitation are reduced from nearly 100% to 20% and 70% for substrates of bare glass and plasmonically active substrate, respectively. Our results pave promising ways for optimization of the biomimetic solar fuel cells due to synergy of the plasmon-induced absorption enhancement together with improved photostability of the molecular machinery of the solar-to-fuel conversion.

Fabrication Friendly Plasmonic Metasurface Sensing and Switching Configuration Based on Plasmonic Induced Absorption: Analytical and Numerical Evaluation

Fabrication Friendly Plasmonic Metasurface Sensing and Switching Configuration Based on Plasmonic Induced Absorption: Analytical and Numerical Evaluation

Dual dynamically tunable plasmon-induced transparency and absorption in I-type-graphene-based slow-light metamaterial with rectangular defect

A simple quasi-continuous I-type-graphene-based metamaterial with rectangular defect is proposed to realize a dual dynamically tunable plasmon-induced transparency (PIT) and plasmon-induced absorption (PIA) effect. The desired Fermi levels of the monolayer graphene can be dynamically tuned by applying the bias voltage, which can produce the spectral shift of the dual PIT and PIA. What’s interesting is that the dual PIT (PIA) can be evolved into the single PIT (PIA) by tuning the distance between two vertical graphene ribbons in the metamaterial. In addition, the distribution intensity and directions of electric field vectors are used to illustrate the distributions of electric field magnitude in the monolayer graphene metamaterial under the action of the polarized incident light. Both theoretical analysis and numerical simulation methods are introduced to study the mechanism of the PIT and PIA effect at terahertz frequency range, and they display very good consistency. Moreover, the surface plasmon polaritons (SPPs) of the monolayer graphene have a better dispersion property and a broad frequency range of the group delay, the maximum group delay of about 0.25 ps is obtained in the proposed metamaterial structure. The proposed metamaterial may have extensive applications in absorbers, tunable switches and slow light devices, et al.

Frontispiece: Dual Plasmonic Au−Cu2−xS Nanocomposites: Design Strategies and Photothermal Properties

The integration of Au and Cu2−xS into a single nanoplatform offers several advantages that can be leveraged in emerging photothermal-based applications. This Minireview presents a timely reference on the design and synthesis of Au−Cu2−xS nanocomposites with tunable plasmon-induced absorption features and light-to-heat conversion properties. A preview of their prospective use as photothermally responsive agents for cancer therapy and theranostics is also provided. For more information, see the Minireview by E. A. D. R. Hans and M. D. Regulacio on page 11030 ff.

Atomic-level insights into the activation of nitrogen via hydrogen-bond interaction toward nitrogen photofixation

Summary As the activation of N2 molecules is generally regarded as the bottleneck in N2 reduction, it is of significant importance to develop promising strategies to efficiently activate N2 molecules. Herein, we discovered an innovative approach to activate N2 molecules via hydrogen-bond interaction in N2 photofixation. Porous Cu with surface modification of S atoms (3%-S/Cu) exhibited remarkable catalytic activity and stability in N2 photofixation. Further mechanistic studies revealed that surface S atoms directly participated in the catalytic process by accepting and donating H atoms. In addition, the forming S–H bond significantly promoted the activation of N2 molecules via hydrogen-bond interaction, contributing to the enhanced catalytic activity.

Terahertz plasmonic sensing based on tunable multispectral plasmon-induced transparency and absorption in graphene metamaterials

Graphene surface plasmons have gained wide interest due to their promising applications in terahertz technology. In this paper, we propose an easily implemented monolayer graphene structure, and exploit its quadra resonance mode to achieve triple plasmon-induced transparency (PIT) and triple plasmon-induced absorption (PIA) effects. A uniform theoretical model with four resonators is introduced to elaborate the intrinsic coupling mechanism and examine the accuracy of simulated results. By altering the Fermi energy and the carrier mobility of the graphene, the proposed triple PIT (PIA) system exhibits a dynamically tunable property, and the absorption intensity can be controlled over a broadband frequency range. It is found that the absorption intensity of the triple PIA spectrum can be as high as 50% with four absorption bands, which is 20 times more than that of monolayer graphene. Besides, we further investigate the triple PIT system for terahertz plasmonic sensing applications, and it is shown that the highest sensitivity of 0.4 THz RIU−1 is reached. Thus, the triple PIT system we propose can be employed for multi-band light absorption and plasmonic optical sensing.

Plasmon-induced visible light absorption arising from edge-interfaces of titanium-oxides nanocomposites

The efficient utilization of visible light on wide-bandgap metal-oxides is a long-term goal but is still a grand challenge for plasmon-driven chemistry. The plasmon-induced concentration of photons in adjacent materials provides a strategic pathway to extend the light-harvesting regime to sub-bandgap. With the abundant edge-spots in surface nanostructures, here, we report that the titanium-oxides nanocomposites composed of the metallic titanium coupled with its oxides exhibit significant resonant visible absorption. The experimental characterizations with computational analyses demonstrate that the excited plasmon resonance at edge-interfaces results in the unique visible absorption band. Localized field-enhancement, charge-scattering, and hot-electrons effects conclusively confirm that the visible absorption is derived from the plasmon resonance, rather than the narrowing of bandgap or energy levels of impurities or defects. The plasmon-induced absorption effectively enhances the separation and transfer of photogenerated charge carriers leading to improved photoactivity. Our results help to advance titanium-oxides nanocomposites towards plasmonic chemistry in the visible-light region and highlight a potential general route to harnessing photons beyond the bandgap limitation based on plasmonic metal-oxides nanocomposites.

Wide-angle perfect absorber using a 3D nanorod metasurface as a plasmonic sensor for detecting cancerous cells and its tuning with a graphene layer

We investigate a high-sensitivity plasmonic sensor that uses a hexagonal nanorod array metasurface with for identifying malignant hepatic metastases from healthy liver cells. This designed plasmonic metasurface has some advantages such as nanoscale dimensions, a high figure of merit and sensitivity to the refractive index, and insensitivity to the incident angle for 0° to 60°. With the 3D finite-difference time domain method, we study the output characteristics and the effect of geometrical parameters, materials, and incident angle on the plasmon-induced absorption resonances as well. A sensitivity of 1250 nm per refractive index unit (RIU) can be achieved when the change of the sensing medium refractive index Δn=0.2, and the maximum figure of merit achieved is about 610 RIU−1. Also, graphene metasurfaces are used to obtain tunable characteristics. Our proposed structure not only has a nanoscale footprint of 200×200×50 nm3, but also its plasmon-induced absorption resonances are not sensitive to the incident angle. This device holds great potential for the design of nanosensor devices and perfect absorbers.

Enhancing Solar Water Splitting of Textured BiVO4 by Dual Effect of a Plasmonic Silver Nanoshell: Plasmon-Induced Light Absorption and Enhanced Hole Transport

Herein, we demonstrate high-efficiency photoelectrochemical (PEC) water oxidation by combining a textured BiVO4 (t-BVO) photoanode with double-deck structured SiO2@Ag nanoparticles (NPs) with a Ag ...

Dynamically tunable excellent absorber based on plasmon-induced absorption in black phosphorus nanoribbon

The realization of plasmon-induced absorption (PIA) via local plasmon resonance coupling on the surface of two-dimensional metamaterials based on nanostructures heavily depends on the well-designed patterned antenna. However, due to the limitation of nanostructures’ size and the difficulty of material formation, it is challenging to achieve the expected performance of such a device. We propose and numerically simulate PIA in response to mid-infrared using two black phosphorus (BP) layers that are composed of upper double BP ribbons and lower single BP ribbons to avoid BP chips patterning. The theoretical transmission spectrum of the structure calculated by the coupled mode theory is in good agreement with the simulated curve. The resonant intensity of the reflection window is affected by interlayer spacing, and the resonant wavelength of the reflection window can be realized by dynamically varying carrier density. The absorption performance of the system can be enhanced not only by the gold mirror that is totally reflected at the bottom of the structure but also by the polarization angle of the incident wave. The designed system could be expected on various optical devices, including plasmonic sensors, dual-frequency absorbers, and switch controllers.

The vibronic absorption spectra and exciton dynamics of plasmon-exciton hybrid systems in the regimes ranged from Fano antiresonance to Rabi-like splitting.

The complex interplay between molecules and plasmonic metal nanoparticles (MNPs) presents a set of particular characteristics in absorption/scattering spectra such as excitonic splitting, asymmetric line shapes, plasmon-induced absorption enhancement and transparencies, etc. Although the MNP-molecule systems have been intensively investigated experimentally and theoretically, the construction of a theoretical framework which can produce all the disparate experimental observations and account for the electron-phonon (e-p) coupling is still in progress. Here, we present a theoretical approach which can account for both the plasmon-exciton coupling and the e-p interaction and produce all the spectral line shapes ranging from Fano antiresonance to Rabi splitting by simply tuning the coupling strength or plasmon damping rate. Additionally, we demonstrate the evolution of vibronic spectra and exciton dynamics with the coupling strength, plasmon damping rate, and detuning energy. It is found that the vibronic structures appearing in Rabi-like spectra are worse resolved, wider, and more largely shifted than those appearing in the Fano regime, attributed to the more significant deformation of the molecular vibrational wavepacket in the Rabi-like regime than that in the Fano regime as the molecular e-p interaction increases. The positive/negative value of detuning energy can induce different degrees of the vibrational wavepacket deformation and subsequently a different effect on the spectra in different coupling regimes.

(Metal yolk)/(porous ceria shell) nanostructures for high-performance plasmonic photocatalysis under visible light

We describe a route to the preparation of (metal yolk)/(porous ceria shell) nanostructures through the heterogeneous growth of ceria on porous metal nanoparticles followed by the calcination-induced shrinkage of the nanoparticles. The approach allows for the control of the ceria shell thickness, the metal yolk composition and size, which is difficult to realize through common templating approaches. The yolk/shell nanostructures with monometallic Pt and bimetallic PtAg yolks featuring plasmon-induced broadband light absorption in the visible region are rationally designed and constructed. The superior photocatalytic activities of the obtained nanostructures are demonstrated by the selective oxidation of benzyl alcohol under visible light. The excellent activities are ascribed to the synergistic effects of the metal yolk and the ceria shell on the light absorption, electron-hole separation and efficient mass transfer. Our synthesis of the (metal yolk)/(porous ceria shell) nanostructures points out a way to the creation of sophisticated heteronanostructures for high-performance photocatalysis.