Search Results (42)

Conventional all-optical modulators based on surface plasmon polaritons (SPPs) primarily utilize the nonlinear effect of a given material for modulation. Their performance is heavily dependent on the optical properties of the dielectric materials used and requires high pumping power. However, manipulating SPPs by controlling electron concentrations offers a material-independent approach suitable for all-optical modulators. In this paper, we propose a hybrid gold–ITO–silver block structure integrated within a Mach–Zehnder interferometer configuration to address this problem. The gold–ITO interface effectively localizes propagating SPPs. The pump light excites localized surface plasmons (LSPs) in the silver block, generating surface electric fields that modulate the electron concentration in the adjacent ITO layer. The extinction ratio is 50.8 dB when the electron concentration changes by 3.3 × 10²⁰ cm⁻³, indicating that this structure is an all-optical modulator with a high extinction ratio. This approach shows significant promise for reducing pump power and enhancing the performance of all-optical modulators. Full article

Near-field imaging of the hybrid surface plasmon-phonon polaritons on the n-GaN semiconductor was performed using a scattering scanning near-field optical microscope at the selected frequencies of 920 cm⁻¹ and 570 cm⁻¹. The experimental measurements and numerical modeling data were in good agreement, revealing the large propagation distances on the n-GaN semiconductor and other insights which could be obtained by analyzing the dispersion characteristics of hybrid polaritons. In particular, the decay lengths of polaritons at the excitation frequency of 920 cm⁻¹ were measured to be up to 25 and 30 µm in experiment and theory, respectively. In the case of excitation at the frequency of 570 cm⁻¹, the surface plasmon-phonon polaritons’ decay distances were 25 µm and 105 µm, respectively, noting the limitations of the near-field optical microscope setups used. Dispersion characteristics of the resonant frequency and the damping rate of hybrid polaritons were numerically modeled and compared with the analytical calculations, validating the need for further experiment improvements. The launch conditions for the near-field observation of extraordinary coherence of the surface plasmon-phonon polaritons were also discussed. Full article

This paper introduces a novel miniaturized, four-mode, semi-flexible leaky wave Multiple-Input Multiple-Output (MIMO) antenna specifically designed to advance vehicular communication systems. The proposed antenna addresses key challenges in 5G low- and high-frequency bands, including millimeter-wave communication, by integrating innovative features such as a periodic Spoof Surface Plasmon Polariton Transmission Line (SSPP-TL) and logarithmic-spiral-like semi-circular strip patches parasitically fed via orthogonal ports. These design elements facilitate stable impedance matching and wide impedance bandwidths across operating bands, which is essential for vehicular networks. The hybrid combination of leaky wave and SSPP structures, along with a defected wide-slot ground structure and backside meander lines, enhances radiation characteristics by reducing back and bidirectional radiation. Additionally, a naturalization network incorporating chamfered-edge meander lines minimizes mutual coupling and introduces a fourth radiation mode at 80 GHz. Compact in size (14 × 12 × 0.25 mm³), the antenna achieves high-performance metrics, including S11 < −18.34 dB, dual-polarization, peak directive gains of 11.6 dBi (free space) and 14.6 dBi (on vehicles), isolation > 27 dB, Channel Capacity Loss (CCL) < 3, Envelope Correlation Coefficient (ECC) < 0.001, axial ratio < 2.25, and diversity gain (DG) > 9.85 dB. Extensive testing across various vehicular scenarios confirms the antenna’s robustness for Vehicle-to-Vehicle (V2V), Vehicle-to-Pedestrian (V2P), and Vehicle-to-Infrastructure (V2I) communication. Its exceptional performance ensures seamless connectivity with mobile networks and enhances safety through Specific Absorption Rate (SAR) compliance. This compact, high-performance antenna is a transformative solution for connected and autonomous vehicles, addressing critical challenges in modern automotive communication networks and paving the way for reliable and efficient vehicular communication systems. Full article

Metal–insulator–metal (MIM) waveguide-based plasmonic sensors are significantly important in the domain of advanced sensing technologies due to their exceptional ability to guide and confine light at subwavelength scales. These sensors exploit the unique properties of surface plasmon polaritons (SPPs) that propagate along the metal–insulator interface, facilitating strong field confinement and enhanced light–matter interactions. In this review, several critical aspects of MIM waveguide-based plasmonic sensors are thoroughly examined, including sensor designs, material choices, fabrication methods, and diverse applications. Notably, there exists a substantial gap between the numerical data and the experimental verification of these devices, largely due to the insufficient attention given to the hybrid integration of plasmonic components. This disconnect underscores the need for more focused research on seamless integration techniques. Additionally, innovative light-coupling mechanisms are suggested that could pave the way for the practical realization of these highly promising plasmonic sensors. Full article

Digital multipliers are the core components of digital computers, and improving the speed of transistor electronic computers during computation has almost reached its limit, with high power consumption. In this paper, we proposed an electro-optic hybrid multidigit digital multiplier based on SPP technology, which has the advantages of high speed and low power consumption in optical logic, as well as flexible electrical operation and easy storage. The electro-optic hybrid digital multiplier mainly consists of an electrical AND logic gate, an electro-optic hybrid half adder, and an electro-optic hybrid full adder. The optical logic unit is controlled by activated ITO materials to achieve optical-domain operations, and then the multiplication calculation results are converted into electrical signals through photoelectric conversion. The experimental results show that when the scale is 64 × 64 bits, compared with transistor digital multiplication, the energy consumption is reduced by 48.8%; the speed is increased by a factor of 28; and the volume of the electro-optic hybrid digital multiplier device is larger than that of the transistor multiplier, saving 59.9% of the area. For optical transmission loss, a single adder outputs 0.31 dB at different device scales, while the carry output continuously increases with device scale. At scales of 8 × 8 bits, 16 × 16 bits, and 64 × 64 bits, the insertion losses at the sum output ports are 1.03 dB/μm and 1.87 dB/μm, respectively. Full article

Ultrathin cells are gaining popularity due to their lower weight, reduced cost, and enhanced flexibility. However, compared to bulk cells, light absorption in ultrathin cells is generally much lower. This study presents a numerical simulation of a metamaterial light management structure made of ultrathin lead sulfide colloidal quantum dots (PbS CQDs) sandwiched between a top ITO grating and a tungsten backing to develop an efficient hybrid solar/thermophotovoltaic cell (HSTPVC). The optical properties were computed using both the finite integration technique (FIT) and the finite element method (FEM). The absorptance enhancement was attributed to the excitations of magnetic polaritons (MP), surface plasmon polaritons (SPP), and lossy mode resonance (LMR). The HSTPVC with the metamaterial optical light management structure was assessed for short-circuit current density, open-circuit voltage, and conversion efficiency. The results show a conversion efficiency of 18.02% under AM 1.5 solar illumination and a maximum thermophotovoltaic conversion efficiency of 12.96% at TB = 1600 K. The HSTPVC can operate in a hybrid solar/thermal conversion state when the ITO grating is included by combining the advantages of QDs and metamaterials. This work highlights the potential for developing a new generation of hybrid STPV cells through theoretical modeling and numerical simulations. Full article

In this study, a Kretschmann structure with a hybrid layer of graphene–WS₂ is designed to develop a sensitive biosensor for deoxyribonucleic acid detection. The biosensor incorporates a 45 nm gold layer as the active layer and a thin film of chrome as the adhesive layer. Through the optimization of the graphene and WS₂ layers, combined with the implementation of a silicon layer, we can enhance the nano-sensor’s sensitivity. The thin silicon layer acts as a protective barrier for the metal, while also increasing the volume of interaction. Consequently, by adjusting the thickness of the active metal and adding a silicon layer, we achieve higher sensitivity and a lower full width at half maximum, leading to sensitivity of 333.33°/RIU. The designed structure is analyzed using numerical techniques and the finite difference time domain method, allowing us to obtain the optical characteristics of the surface plasmon polariton sensor. Various parameters are calculated and evaluated to determine the optimal conditions for the sensor. Furthermore, the total size of the sensor is 2.228 µm². Full article

To keep pace with the demands of modern photonic integration technology, the electro-optic modulator should feature multi-parameter tunable components and a compact size. Here, we propose a hybrid structure that can modulate the multi-parameters of surface plasmon polaritons (SPPs) simultaneously with a compact size by controlling the electron concentration of indium tin oxide (ITO) in the near-infrared spectrum. The length, width and height of the device are only 15 μm, 5 μm and 9 μm, respectively. The numerical results show that when the electron concentration in ITO changes from 7.5 × 10²⁶ m⁻³ to 9.5 × 10²⁶ m⁻³, the variation in amplitude, wavelength and phase are 49%, 300 nm and 347°, respectively. The demonstrated structure paves a new way for multi-parameter modulation and the realization of ultracompact modulators. Full article

We present an integrated device combining a double L-shaped chiral metasurface with long-wavelength GaAs/AlGaAs quantum well infrared photodetectors (QWIPs), achieving a circular polarized extinction ratio (CPER) as high as 45 in the long-wavelength infrared range of 7–9 μm. The unit of the chiral metasurface array consists of two structurally identical L-shaped gold structures with central symmetry. The CPER of the double L-shaped QWIPs is 14 times higher than that of a single L-shaped QWIP. The device operates in three modes within the detection band: the microcavity mode, the surface plasmon polariton (SPP) mode, and the hybrid mode. The double L-shaped chiral structure selects and reflects a small portion of left-handed circularly polarized light (LCP), while the majority enters the device and excites SPP modes with the bottom gold grating layer, leading to an absorption enhancement. In contrast, right-handed circularly polarized light (RCP) is mostly reflected with limited excitation of SPP waves. QWIPs exhibit a peak absorption of 0.8 and a coupling efficiency of 2700% in the active region of the quantum well due to the combined effects of the microcavity and SPP modes, in which the SPP mode plays a dominant role. The proposed device maintains high circular polarization discrimination capability under large incident angles and can be applied in spectral imaging. Full article

In this paper, a novel broadband balanced-to-balanced (BTB) filtering power divider (FPD) utilizing the half-mode substrate-integrated waveguide and spoof surface plasmon polariton (HMSIW-SSPP) hybrid transmission line is introduced. Initially, a new HMSIW-SSPP unit cell is proposed, demonstrating a lower upper cut-off frequency compared to the classical HMSIW-SSPP unit cell. Building upon this unit cell, a bandpass BTB FPD is devised employing dual-layer stacked substrates, enabling independent control over the passband’s lower and upper cut-off frequencies through specific physical dimensions. Additionally, the incorporation of isolation resistors and defected ground structures in the BTB FPD enhances differential-mode isolation and common-mode (CM) suppression between output ports. A manufactured and tested BTB FPD prototype validates this design method, showcasing a broad fractional bandwidth of 52.31% (6.72–11.48 GHz), output port isolation surpassing 14.25 dB, and transmitted CM suppression exceeding 34.05 dB. Full article

A giant electric field on a subwavelength scale is highly beneficial for boosting the light–matter interaction. In this paper, we investigated a hybrid structure consisting of a hemispheric dimer array and a gold film and realized resonant mode coupling of the surface lattice resonance (SLR) and surface plasmon polariton (SPP). Mode coupling is demonstrated by observing anti-crossing in reflection spectra, which corresponds to Rabi splitting. Although the resonance coupling does not enter the strong coupling regime, an improved quality factor (Q~350) and stronger electric field enhancement in the gap region of the dimer (i.e., hot spot) in our hybrid structure are obtained compared to those of the single dimer or dimer array only. Remarkably, the magnitude of electric field enhancement over 500 can be accessible. Such high field enhancement makes our hybridized structure a versatile platform for the realization of ultra-sensitive biosensing, low-threshold nanolasing, low-power nonlinear optical devices, etc. Full article

In this paper, a long-range hybrid waveguide for subwavelength confinement based on double SPP coupling is proposed. The hybrid waveguide consists of a metal-based cylindrical hybrid waveguide and a silver nanowire. There are two coupling regions in the waveguide structure that enhance mode coupling. Strong mode coupling enables the waveguide to exhibit both a small effective mode area (0.01) and an extremely long transmission length (700 μm). The figure of merit (FOM) of the waveguide can be as high as 4000. In addition, the cross-sectional area of the waveguide is only 500 nm × 500 nm, allowing optical operation in the subwavelength range, which helps enhance the miniaturization of optoelectronic devices. The excellent characteristics of the hybrid waveguide make it have potential applications in photoelectric integrated systems. Full article

In this study we investigate the optical properties of a 2D-gap surface plasmon metasurface composed of gold nanoblocks (nanoantennas) arranged in a metal–dielectric configuration. This novel structure demonstrates the capability of generating simultaneous multi-plasmonic resonances and offers tunability within the near-infrared domain. Through finite difference time domain (FDTD) simulations, we analyze the metasurface’s reflectance spectra for various lattice periods and identify two distinct dips with near-zero reflectance, indicative of resonant modes. Notably, the broader dip at 1150 nm exhibits consistent behavior across all lattice periodicities, attributed to a Fano-type hybridization mechanism originating from the overlap between localized surface plasmons (LSPs) of metallic nanoblocks and surface plasmon polaritons (SPPs) of the underlying metal layer. Additionally, we investigate the influence of dielectric gap thickness on the gap surface plasmon resonance and observe a blue shift for smaller gaps and a spectral red shift for gaps larger than 100 nm. The dispersion analysis of resonance wavelengths reveals an anticrossing region, indicating the hybridization of localized and propagating modes at wavelengths around 1080 nm with similar periodicities. The simplicity and tunability of our metasurface design hold promise for compact optical platforms based on reflection mode operation. Potential applications include multi-channel biosensors, second-harmonic generation, and multi-wavelength surface-enhanced spectroscopy. Full article

In this work, we demonstrate that optical pulling forces (OPFs) can be induced by a hybrid dimer consisting of a Si nanoparticle (NP) and a coated nanoparticle with a gain core and Au shell under normal plane wave illumination. Analytical theory reveals that the underlying physical mechanism relies on interactions between the electric dipole (ED) modes excited in the NPs. As compared with the individual NP, it is found that the magnitude of optical force can be enlarged by almost three orders for the Si NP and one order for the coated gain NP in the coupled dimer. In addition, we find that the OPFs exerted on the NPs are heavily dependent on the gain level of the core materials, the incident polarization angle and the sizes of the NPs. More interestingly, we find that the OPF can also be exerted on a trimer system consisting of two identical Si NPs and a coated NP arranged in a line. The related results could be used to propose a versatile platform for manipulating NPs. Full article

A dual-major-axis grating composed of two metal–insulator–metal (MIM) waveguides with different dielectric layer thicknesses is numerically proposed to achieve the function of the quarter-wave plate with an extremely large bandwidth (1.0–2.2 μm), whose optical properties can be controlled by the Fabry–Pérot (FP) resonance. For the TE incident mode wave, MIM waveguides with large (small) dielectric layer thicknesses control the guided-mode resonant channels of long (short) waves, respectively, in this miniaturized optical element. Meanwhile, for the TM incident mode wave, the propagation wave vector of this structure is controlled by the hybrid mode of two gap-SPPs (gap-surface plasmon polaritons) with different gap thicknesses. We combine this structure with a thick silver grating to propose a circularly polarizing dichroism device, whose effective bandwidth can reach an astonishing 1.65 $\mathsf{\mu }\mathrm{m}$ with a circular polarization extinction ratio greater than 10 dB. The full Stokes pixel based on the six-image element technique can almost accurately measure arbitrary polarization states at 1.2–2.8 $\mathsf{\mu }\mathrm{m}$ (including elliptically polarized light), which is the largest bandwidth (1600 nm) of the full Stokes large-image element to date in the near-infrared band. In addition, the average errors of the degree of linear polarizations (Dolp) and degree of circular polarizations (Docp) are less than −25 dB and −10 dB, respectively. Full article