Surface Plasmon Polariton Waves Research Articles

Detection of Vegetable Oil Variance Using Surface Plasmon Resonance (SPR) Technique

The difference between coconut oil, corn oil, olive oil, and palm oil has been detected using surface plasmon resonance (SPR) technique. This is a new method in material characterization that can be used to identify vegetable oil variance. The SPR curve was measured by SPR system consisting of optical instruments, mechanical instruments, Main UNIT, and user interface (computer). He-Ne laser beam of wavelength 633 nm was used as light source, while gold (Au) thin film evaporated on half cylinder prism was used as the base so that surface plasmon polariton (SPP) waves propagate at the interface. Tween-80 and PEG-400 are used as surfactant and co-surfactant to make water-oil emulsion from each sample. The sample was prepared with the ratio of oil: surfactant: co-surfactant as 1:2:1 and then stirred on the water to make emulsions. The angle shift was measured by the change of SPR angle from prism/Au/air system to prism/Au/water-oil emulsion. The different SPR angle of each sample has been detected in the various number of spray, a method that was used for depositing the emulsion. From this work, we conclude that the saturated fatty acid component was the most significant component that changes the refractive index in the vegetable oil in water emulsion that can be used to characterize the vegetable oil variance.

High directivity plasmonic graphene-based patch array antennas with tunable THz band communications

This paper proposes patch array antennas based on graphene with plasmonic characteristics in THz application. Here, the proposed structure is based on two graphene rectangular patch elements in horizontal plane which presents behavior of Surface Plasmon Polariton (SPP) waves. Also, analyzing the graphene characteristics are studied in details. The numerical simulations with CST, Computer Simulation Technology transient solver, and COMSOL are presented in array antenna structure. The efficiency is improved by using array antenna and also by increasing the graphene layers. Parametric study method is used to achieve desired tunable low terahertz band communication.

Spoof Surface Plasmon Polaritons Power Divider with large Isolation

Periodic corrugated metal structure is designed to support and propagate spoof surface plasmon polaritons (SSPPs) wave in the microwave frequencies. In this paper, firstly a plasmonic waveguide consisting of oval-ring shaped cells is proposed with the performance of high transmission efficiency in a wide frequency range. The coplanar waveguides (CPWs) with 50 Ω impedance are adopted to feed the energies or extract signals at both ends of the plasmonic waveguide. Then a well-isolated power divider is constructed based on the SSPPs waveguides aiming to equally split the energy of the SSPPs wave into two equal parts. The stepped-impedances are co-designed with the three input/output ports of the power divider to achieve the impedance-matching between the SSPPs waveguides and the coplanar waveguides. Besides, a single resistor is placed in the middle of two symmetrical half oval-rings to realize the isolation between the two output ports over the spectrum of 4.5–7.5 GHz. Finally, both plasmonic waveguide and the power divider are fabricated and tested to verify the predicted characteristics.

Dynamic tailoring of surface plasmon polaritons through incident angle modulation

Dynamic tailoring of the propagating surface plasmon polaritons (SPPs) through incident angle modulation is proposed and numerically demonstrated. The generation and tailoring mechanism of the SPPs are discussed. The relationship formula between the incident angle and the generated SPP wave vector direction is theoretically derived. The correctness of the formula is verified with three different approaches using finite difference time domain method. Using this formula, the generated SPP wave vector direction can be precisely modulated by changing the incident angle. The precise modulation results of two dimensional Bessel-like SPP beam and SPP bottle beam array are given. The results can deepen the understanding of the generation and modulation mechanism of the SPPs.

Metal-Dielectric Composite Holography for Controlling the Propagations of Surface Plasmon Polaritons

Controlling the propagations of surface plasmon polaritons (SPPs) is important for many applications. Now, mainly structures for controlling SPPs are etched directly in the metal surface through experimental methods, such as focus ion beam lithography (FIB). In view of mature technology in processing dielectric products, we propose the metal-dielectric composite holography (MDCH) method to design dielectric structures for controlling the propagation of SPPs. The holographic groove structures are designed in dielectric film to control SPP propagation through the surface electromagnetic wave holography (SWH) method. The mutual coherence theory is applied to analyze the influence of the grooves in dielectric film on the phase of propagating SPPs, and the reconstruction condition is obtained. Based on the analysis results, two schemes are proposed to make MDCH structures satisfy the condition: reducing the width of the grooves or filling the grooves with another dielectric. The finite difference time domain (FDTD) method is applied to test the two schemes. Simulation results prove that two schemes are feasible when the width of the groove is smaller than 40 nm or the refractive index of the filling dielectric is limited to a certain range. The investigation verifies that the MDCH method is feasible and the SPP waves can be controlled with high efficiency. Based on the investigation, the mature hologram-fabricated methods and dielectric-processing methods may be used to fabricate structures for controlling SPP waves. The MDCH method may open up the possibility for mass production of plasmonic devices, avoiding the FIB experimental method.

Design of plasmonic rectangular ribbon antenna based on graphene for terahertz band communication

This study proposes a new idea for designing antenna based on graphene for THz application in detailed analysis. Here, design of a novel graphene-based ribbon antenna is presented based on surface plasmon polariton (SPP) behavioural in graphene. Noble metals support and confine EM waves in infrared region. However, SPP wave propagation is supported by graphene in much lower frequencies of infrared region, in THz region. The conductivity of graphene and SPP waves behavioural in graphene sheet is analysed and studied for designing antenna based on new idea of ribbon antenna. The numerical simulations with COMSOL and CST are presented in proposed new idea structure of antenna. In order to achieve the desired tunable THz band communication, the parametric study method is used for the proposed graphene-based ribbon antenna to achieve higher efficiency.

Excitation of Multiple Surface Plasmon-Polaritons by a Metal Layer Inserted in an Equichiral Sculptured Thin Film

Excitation of multiple surface plasmon-polaritons(SPPs) by an equichiral sculptured thin film with a metal layer defect was studied theoretically in the Sarid configuration, using the transfer matrix method. Multiple SPP modes were distinguished from waveguide modes in optical absorption for p- polarized plane wave. The degree of localization of multiple SPP waves was investigated by calculation of the time averaged Poynting vector. The results showed that the long-range and short-range SPP waves can simultaneously be excited at both interfaces of metal core in this proposed structure which may be used in a broad range of sensing applications.

Differentiating surface plasmon-polariton waves and waveguide modes guided by interfaces with one-dimensional photonic crystals

One-dimensional photonic crystals (PCs) are made of planar layers of different materials with periodic arrangement. Such PCs can support multiple surface waves at their interfaces with homogeneous materials as well as multiple waveguide modes guided by individual constituent layers. The numerical results comparing multiple surface plasmon-polariton (SPP) waves and waveguide modes guided by a metal and a PC with only two layers in each period indicated that the periodic nonhomogeneity and the waveguide modes guided by the individual layers in the PC engender the multiplicity of SPP waves. For smaller value of the period of the PC, the coupling of the individual layers in the PC near the metal/PC interface gives rise to new SPP waves but the coupling reduces as the period increases and waveguide modes dominate. The differentiation between the waveguide modes and the surface waves is necessary to fully exploit the promise of photonic crystals in integrated optics.

Design and Simulation of a New Coaxial Probe for Near Field Scanning Optical Microscopy

Design of the new photonic devices having attractive optical properties such as subwavelength confinement of light has a numerous applications in developing nanoscale sensors, photonic integrated circuits, solar cells and etc. Abbe’s diffraction limit restricts the use of subwavelength scale photonic elements due to their size and therefore new approaches are required in order to achieve desirable nanometer scale properties of these devices. Delivering light energy to nanometer scale regions can be achieved by surface plasmon polariton (SPP) waves that propagate in metal-dielectric interface. The paper presents results in FDTD (finite-difference time domain) simulation of a new coaxial probe of nanometer-scale size.Based on FDTD simulations of the coaxial probe field localization and enhancement in the region around the tip of coaxial probe has been obtained. Configuration of the probe consists of the truncated Au cone as a core, truncated dielectric (SiO2) cone in the middle and outer metallic cladding. Simulations of the probe revealed that increasing the radius of Au core structure could lead to the enhanced field around the tip. Additionally, increasing radius of outer cladding layer doesn’t affect field enhancement around the tip. Different configurations of the probe have been analyzed in the range of visible spectrum of the source and as a result the most promising configuration has been selected

Characterization of Au/Fe/Au and Au/Co/Au Magneto-Plasmonic Multilayers as an Ethanol Vapor Sensor

In this paper, we investigate the sensing performance of Au/Fe/Au and Au/Co/Au magneto-plasmonic nanostructures as transducers as well as the performance of TiO2 thin film and TiO2 NPs as sensing layers. A comparison between sensing performance of the traditional surface plasmon resonance (SPR) and the magneto-optic (MO) SPR (MOSPR) transducing techniques is presented here. The surface plasmon wave vector in these transducers which are consisted of metallic and magnetic materials is modulated by external magnetic field in the transverse configuration. Magneto-plasmonic structures show a great enhancement of an MO Kerr effect when the SPR condition is satisfied. As such enhancement strongly depends on the excitation conditions of the surface plasmon polariton (SPP) and, therefore, on the refractive index of the dielectric in contact with the metal layer, we use this enhanced MO signal as the sensing magnitude for investigating molecular interactions between ethanol vapor and TiO2 nanostructures onto the transducers. Besides, when the SPP is excited, applied magnetic field would modulate the SPP wave vector. The modulated nature of MOSPR signal would lead to a higher sensing performance in terms of sensitivity and signal-to-noise ratio with respect to the traditional SPR signal. Moreover, our results show that using TiO2 NPs in the vicinity of multilayer transducers creates a better sensing performance which is caused by porosity and enhancement in the surface area of absorbent layer.

Spin and momentum of the light fields in inhomogeneous dispersive media with application to surface plasmon-polariton waves

Following to the recently published approach [Phys. Rev. Lett. 119, 073901 (2017); New J. Phys., 123014 (2017)], we refine and accomplish the general scheme for the unified description of the momentum and angular momentum in complex media. The equations for the canonical (orbital) and spin linear momenta, orbital and spin angular momenta in a lossless inhomogeneous dispersive medium are presented in the compact form analogous to the Brillouin's relation for the energy. The results are applied to the surface plasmon-polariton (SPP) field, and the microscopic calculations support the phenomenological expectations. The refined general scheme correctly describes the unusual SPP properties (transverse spin, magnetization momentum) and additionally predicts the singular momentum contribution sharply localized at the metal-dielectric interface, which is confirmed by the microscopic analysis. The results can be useful in optical systems employing the structured light, especially for microoptics, plasmophotonics, optical sorting and micromanipulation.

Plasmonic patch antenna based on graphene with tunable terahertz band communications

This paper proposes a plasmonic graphene-based patch antenna for THz application in detailed analysis. Here, a rectangular patch antenna based on graphene presenting the Surface Plasmon Polariton (SPP) waves behavioral in graphene sheet is proposed and analyzed. In addition, the characteristics of graphene are presented and analyzed. In the Ffollowing, the SPP wave propagation in graphene is numerically and analytically studied. The numerical simulations with COMSOL and CST, Computer Simulation Technology transient solver, are presented in proposed structure. These solvers demonstrate that the efficiency of a rectangular graphene patch drastically improved by increasing the graphene layers. In order to achieve the desired low tunable terahertz band communication, parametric study method is applied on the proposed antenna.

Optical momentum and angular momentum in complex media: from the Abraham–Minkowski debate to unusual properties of surface plasmon-polaritons

We examine the momentum and angular momentum (AM) properties of monochromatic optical fields in dispersive and inhomogeneous isotropic media, using the Abraham- and Minkowski-type approaches, as well as the kinetic (Poynting-like) and canonical (with separate spin and orbital degrees of freedom) pictures. While the kinetic Abraham–Poynting momentum describes the energy flux and the group velocity of the wave, the Minkowski-type quantities, with proper dispersion corrections, describe the actual momentum and AM carried by the wave. The kinetic Minkowski-type momentum and AM densities agree with phenomenological results derived by Philbin. Using the canonical spin–orbital decomposition, previously used for free-space fields, we find the corresponding canonical momentum, spin and orbital AM of light in a dispersive inhomogeneous medium. These acquire a very natural form analogous to the Brillouin energy density and are valid for arbitrary structured fields. The general theory is applied to a non-trivial example of a surface plasmon-polariton (SPP) wave at a metal-vacuum interface. We show that the integral momentum of the SPP per particle corresponds to the SPP wave vector, and hence exceeds the momentum of a photon in the vacuum. We also provide the first accurate calculation of the transverse spin and orbital AM of the SPP. While the intrinsic orbital AM vanishes, the transverse spin can change its sign depending on the SPP frequency. Importantly, we present both macroscopic and microscopic calculations, thereby proving the validity of the general phenomenological results. The microscopic theory also predicts a transverse magnetization in the metal (i.e. a magnetic moment for the SPP) as well as the corresponding direct magnetization current, which provides the difference between the Abraham and Minkowski momenta.

Periodic structures on germanium induced by high repetition rate femtosecond laser

Laser-induced periodic surface structures (LIPSS) are studied on germanium surface in air by the femtosecond pulsed laser with repetition frequency of 76 MHz and wavelength λ of 800 nm. Three types of LIPSS were found and they are low-spatial-frequency LIPSS (LSFL), high-spatial-frequency LIPSS (HSFL), and LSFL superimposed with HSFL. The period ΛLSFL of LSFL shrinks quickly from approximately 650 nm to 400 nm (∼λ/2) when lowering the scanning speed. Comparatively, the period ΛHSFL of HSFL keeps almost constant between 90 and 100 nm (∼λ/8) when the scanning speed and the laser pulse energy vary. LSFL and HSFL coexist when the laser pulse energy is around 3.3 nJ/pulse and the scanning speed ranges between 3 and 8 mm/s. The surface plasmon polariton waves make a contribution to the formation of LIPSS and the fourth harmonic generation (FHG) might be involved in the formation of HSFL.

Polarization-switchable and wavelength-controllable multi-functional metasurface for focusing and surface-plasmon-polariton wave excitation.

Realizing versatile functionalities in a single photonic device is crucial for photonic integration. We here propose a polarization-switchable and wavelength-controllable multi-functional metasurface. By changing the polarization state of incident light, its functionality can be switched between the flat focusing lens and exciting surface-plasmon-polariton (SPP) wave. Interestingly, by tuning the wavelength of incident light, the generated SPP waves can also be controlled at desired interfaces, traveling along the upper or lower interface of the metasurface, or along both of them, depending on whether the incident light satisfies the first or second Kerker condition. This polarization-switchable and wavelength-controllable multifunctional metasurface may provide flexibility in designing tunable or multifunctional metasurfaces and may find potential applications in highly integrated photonic systems.

A highly sensitive multiplasmonic sensor using hyperbolic chiral sculptured thin films

Surface plasmon-polariton (SPP) waves guided by an interface of a metal and a hyperbolic chiral sculptured thin film (STF) were theoretically investigated for optical sensing of an analyte. The chiral STF was infiltrated with the analyte to be sensed, and the resulting change in the incidence angle of excitation of the SPP waves in the prism-coupled configuration was computed. The results indicated the potential of this configuration for a plasmonic sensor with sensitivity up to 6000 degrees per refractive index units of the infiltrating fluid in the angular investigation scheme, with multiple SPP waves of the same frequency but different phase speeds, spatial profiles, and sensitivities. The enhancement in the sensitivity is attributed to the high field strength of the SPP waves near the interface. A multiplasmonic sensor is advantageous because of its potential for higher confidence in the measurement of the same analyte.

Modeling of gas breakdown and early transients of plasma evolution in cylindrical all-dielectric resonators

We report on the computational modeling of gas break down and evolution of plasma in an all-dielectric resonator structure. Two cylindrical dielectric resonators (DR) of diameter 25 mm with material relative permittivity of 172.5 separated by a 1 mm gap are observed to resonate in a strong constructive interference mode (CIM) at 1.47 GHz. The electric fields in the gap between the DRs are amplified to about 30 times the incident wave strength which leads to gas breakdown in argon at 10 Torr. The species densities in the bulk of plasma rise primarily due to the wave power addition into the plasma. As the species densities rise above 1017 m−3, the bulk plasma acts as a lossy material and the wave experiences significant damping through collisional losses. As plasma densities in the bulk rise to around 1018 m−3, the wave is damped significantly in the bulk, and a surface plasmon polariton (SPP) wave mode develops at the interface of plasma sheath and the DR surfaces. These surface waves are initiated due to a thin negative permittivity region of the plasma in the vicinity of the DR surface. The quasi-steady state operation of the resonator system depends on the propagation of the damped CIM in the bulk regions of the plasma, the SPP waves in the sheath region and the slower ambipolar diffusion process in plasma. Gas temperature rise in plasma is found to be small throughout the time scales considered and electrostatic fields are found to play an equally important role for large plasma densities in the sheath regions.

Actively controllable terahertz switches with graphene-based nongroove gratings

We systematically investigated the tunable dynamic characteristics of a broadband surface plasmon polariton (SPP) wave on a silicon-graded grating structure in the range of 10–40 THz with the aid of single-layer graphene. The theoretical and numerical simulated results demonstrate that the SPPs at different frequencies within a broadband range can be trapped at different positions on the graphene surface, which can be used as a broadband spectrometer and optical switch. Meanwhile, the group velocity of the SPPs can be modulated to be several hundred times smaller than light velocity in vacuum. Based on the theoretical analyses, we have predicted the trapping positions and corresponding group velocities of the SPP waves with different frequencies. By appropriately tuning the gate voltages, the trapped SPP waves can be released to propagate along the surface of graphene or out of the graded grating zone. Thus, we have also investigated the switching characteristics of the slow light system, where the optical switching can be controlled as an “off” or “on” mode by actively adjusting the gate voltage. The slow light system offers advantages, including broadband operation, ultracompact footprint, and tunable ability simultaneously, which holds great promise for applications in optical switches.

Surface plasmon polariton amplification in a single-walled carbon nanotube.

The interaction of a surface plasmon polariton wave of the far-infrared regime propagating in a single-walled carbon nanotube with a drift current is theoretically investigated. It is shown that under the synchronism condition a surface plasmon polariton amplification mechanism is implemented due to the transfer of electromagnetic energy from a drift current wave into a terahertz surface wave propagating along the surface of a single-walled carbon nanotube. Numerical calculations show that for a typical carbon nanotube surface plasmon polariton amplification coefficient reaches huge values of the order of 106 сm-1, which makes it possible to create a carbon-nanotube-based spaser.

Photovoltaic Ge/SiGe quantum dot mid-infrared photodetector enhanced by surface plasmons.

We report the fabrication and characterization of a multilayer Ge quantum dot detector grown on Si1-xGex virtual substrate (x = 0.18) for photovoltaic mid-wave infrared photodetection. Detector displays an over 100% photovoltaic response enhancement as compared to a conventional Ge/Si device due to smaller hole effective mass in the SiGe barriers. A further enhancement in sensitivity is achieved by excitation of surface plasmon polariton waves in a Ge/SiGe photodetector coupled with a two-dimensional plasmonic structure. The plasmonic resonance induced photocurrent enhancement is found to be larger when the incident infrared light illuminates the detector from its substrate side. At zero bias and 90 K, the responsivity of 40 mA/W and peak detectivity of 1.4 × 1011 cm·Hz1/2/W are determined at a wavelength of 4 µm.