Propagation Of Surface Plasmon Polaritons Research Articles

Waveguide resonance mode response of stacked structures of metallic sub-wavelength slit arrays

Detailed measurements of the optical properties of two-tier systems composed of metallic plates perforated with periodic sub-wavelength slit patterns were carried out using terahertz time-domain spectroscopy. We demonstrate that the transmission properties observed experimentally for various configurations can be reproduced successfully by simulations based on the finite-differential time-domain method. Fabry–Perot-like waveguide resonance mode behaviors specific to this quasi-dielectric system were then investigated. For structures with no lateral displacement between the slit-array plates, mode disappearance phenomena, which are caused by destructive interference between the odd-order mode and the blue- or red-shifted even-order modes, were observed experimentally. The uncommon behavior of the even-order modes was examined precisely to explain the slit-width dependence. For structures with half-pitched displacement between the plates, extraordinarily strong transmission was observed experimentally, even when the optical paths were shut off. This result was interpreted in terms of the propagation of surface plasmon polaritons through very thin and labyrinthine spacings that inevitably exist between the metallic plates. Furthermore, the optical mode disappearance phenomena are revealed to be characterized by anticrossing of the two mixing modes formed by even- and odd-order modes. These experimental observations that are supported theoretically are indispensable to the practical use of this type of artificial dielectric and are expected to encourage interest in optical mode behaviors that are not typically observed in conventional dielectric systems.

Direct measurement of plasmon propagation length of Ag nanowire waveguide via polymer nanofiber launching

Herein, we demonstrate a simple, direct measurement of plasmon propagation length of Ag nanowire waveguide. Using dye-doped polymer nanofiber for launching, propagating surface plasmon polaritons on multiple silver nanowires are efficiently excited under wide-field illumination. By monitoring the length dependence of the intensity of scattering light at the nanowire ends, a typical plasmon propagation length of 15.1 ±1.0μm in Ag nanowire with 120 nm in diameter is directly extracted. Photon–plasmon coupling efficiency of about 40% is determined, which is independent of the orientation of Ag nanowire.

Titanium nitride nanoparticles as an alternative platform for plasmonic waveguides in the visible and telecommunication wavelength ranges

We propose to utilize titanium nitride (TiN) as an alternative material for linear periodic chains (LPCs) of nanoparticles (NPs) which support surface plasmon polariton (SPP) propagation. Dispersion and transmission properties of LPCs have been examined within the framework of the dipole approximation for NPs with various shapes: spheres, prolate and oblate spheroids. It is shown that LPCs of TiN NPs support high-Q eigenmodes for an SPP attenuation that is comparable with LPCs from conventional plasmonic materials such as Au or Ag, with the advantage that the refractory properties and cheap fabrication of TiN nanostructures are more preferable in practical implementations compared to Au and Ag. We show that the SPP decay in TiN LPCs remains almost the same even at extremely high temperatures which is impossible to reach with conventional plasmonic materials. Finally, we show that the bandwidth of TiN LPCs from non-spherical particles can be tuned from the visible to the telecommunication wavelength range by switching the SPP polarization, which is an attractive feature for integrating these structures into modern photonic devices.

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.

Proposition and Numerical Analysis of a Plasmonic Sensing Structure of Metallo-Dielectric Grating and Silver Nano-slabs in a Metal-Insulator-Metal Configuration

We propose and numerically investigate a near-infrared surface plasmon resonance-based refractive index sensor having in unison an extremely high sensitivity (1719 nm/RIU) and transmission efficiency (91.73%) with a high figure of merit (39.81). The proposed sensor structure, consisting of a 1D metallo-dielectric grating of silver and rectangular-shaped silver nano-slabs in a metal-insulator-metal configuration, excites both propagating surface plasmon polaritons and localized surface plasmon polaritons producing highly improved spectral response. Using the finite-difference time-domain computation method, the spectral characteristics were analyzed and some important sensing performances, such as sensitivity, transmission efficiency, full-width at half-maximum, and figure of merit, were optimized through numerical simulations as a function of the shape and size of the nanostructures. As a specific application, the proposed structure was also investigated for temperature sensing application and its temperature sensitivity is found to be much better than the state-of-the-art. The proposed sensor structure may have monumental applications in such areas as biomedical and environmental sensing applications and photonic integrated circuits.

Unidirectional and bidirectional coupling of surface plasmons based on nonperiodic nano slit array

A 2D structure made up of nano slits to couple free space mode of any given wave front to a propagating Surface Plasmon Polariton (SPP) mode of Metal Insulator Metal (MIM) waveguide is proposed. The structure can be designed to act as either a unidirectional coupler or a bidirectional coupler. Designed structures are simulated using FEM technique and results for circular and plane wave fronts are demonstrated. From the results obtained, it is observed that there is an optimum aperture size for coupling maximum power into the MIM waveguide for the case of circular wave front. Full Text: PDF ReferencesMaier S A, Plasmonics: fundamentals and applications (Springer, Berlin 2007). CrossRef Chen J et al.,"Efficient unidirectional generation of surface plasmon polaritons with asymmetric single-nanoslit", Appl. Phys. Lett. 97, 4 (2010) CrossRef Yang X et al., "Unidirectional generation of surface plasmon polaritons by a single right-angled trapezoid metallic nanoslit", J. Phys. D: Appl. Phys., 50, 4 (2017). CrossRef Lu F et al. "An efficient and ultra-broadband unidirectional optical coupler for wide incidence angles", Opt. Commun., 379 (2016). CrossRef Liu D et al., "New RLL Decoding Algorithm for Multiple Candidates in Visible Light Communication", IEEE Photon. Technol. Lett., 27, 15 (2015). CrossRef Wang C M et al., "Angle-Independent Infrared Filter Assisted by Localized Surface Plasmon Polariton", IEEE Photon. Technol. Lett., 20, 13 (2008). CrossRef Wang C M, Feng D Y, "Omnidirectional thermal emitter based on plasmonic nanoantenna arrays", Opt. Express 22, 2 (2014). CrossRef Huang Y, Min C and Veronis G, "Light trapping by backside diffraction gratings in silicon solar cells revisited", Opt. Express 20, 20 (2012). CrossRef Liang X et al., "Undirectional launcher of surface plasmon polaritons based on subwavelength slits with side-illumination and backside-illumination", Optik 127, 3 (2016). CrossRef Dionne J A, Lezec H J and Atwater H A, "Highly Confined Photon Transport in Subwavelength Metallic Slot Waveguides", Nano letters 6, 9 (2006). CrossRef Ghatak, A., & Thyagarajan, K, An introduction to fiber optics Cambridge university press 1998). CrossRef Vial A et al., "Improved analytical fit of gold dispersion: Application to the modeling of extinction spectra with a finite-difference time-domain method", Phys. Rev. B: Condens. Matter, 71, 8 (2005). CrossRef

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.

Spontaneous parametric downconversion of light by a dielectric nanoparticle

In the present paper, we theoretically consider the generation of entangled photon pairs in the process of spontaneous parametric downconversion of light by a nonlinear dielectric nanoparticle. This nanoparticle is the only source of nonlinearity in the considered model. We assume that the particle is small compared to the wavelength of light so that the process is non-resonant. An intuitive theoretical description is developed for the case when the nonlinear susceptibility tensor of the material of a nanoparticle has a form of the Levi-Civita symbol. In this case, a two-photon amplitude which characterizes a spatial distribution of entangled photon pairs can be interpreted as a result of interference between two induced dipoles, both being orthogonal to the direction of polarization of the pump photon. A generation of entangled surface plasmon-polaritons by a dielectric nanoparticle located near the metal-dielectric interface is also considered.

Electric-current-induced unidirectional propagation of surface plasmon-polaritons.

Nonreciprocity and one-way propagation of optical signals are crucial for modern nanophotonic technology, and typically achieved using magneto-optical effects requiring large magnetic biases. Here we suggest a fundamentally novel approach to achieve unidirectional propagation of surface plasmon-polaritons (SPPs) at metal-dielectric interfaces. We employ a direct electric current in metals, which produces a Doppler frequency shift of SPPs due to the uniform drift of electrons. This tilts the SPP dispersion, enabling one-way propagation, as well as zero and negative group velocities. The results are demonstrated for planar interfaces and cylindrical nanowire waveguides.

Near-field plasmonic beam engineering with complex amplitude modulation based on metasurface

Metasurfaces have recently intrigued extensive interest due to their ability to locally manipulate electromagnetic waves, which provide great feasibility for tailoring both propagation waves and surface plasmon polaritons (SPPs). Manipulation of SPPs with arbitrary complex fields is an important issue in integrated nanophotonics due to their capability of guiding waves with subwavelength footprints. Here, an approach with metasurfaces composed of nanoaperture arrays is proposed and experimentally demonstrated which can effectively manipulate the complex amplitude of SPPs in the near-field regime. Tailoring the azimuthal angles of individual nanoapertures and simultaneously tuning their geometric parameters, the phase and amplitude are controlled based on the Pancharatnam-Berry phases and their individual transmission coefficients. For the verification of the concept, Airy plasmons and axisymmetric Airy-SPPs are generated. The results of numerical simulations and near-field imaging are consistent with each other. Besides the rigorous simulations, we applied a 2D dipole analysis for additional analysis. This strategy of complex amplitude manipulation with metasurfaces can be used for potential applications in plasmonic beam shaping, integrated optoelectronic systems, and surface wave holography.

Strong Localization of Surface Plasmon Polaritons with Engineered Disorder.

In this work, we experimentally demonstrate for the first time strong localization of surface plasmon polaritons (SPPs) at visible regime in metallic nanogratings with short-range correlated disorder. By increasing the degree of disorder, the confinement of SPPs is significantly enhanced, and the effective SPP propagation length dramatically shrinks. Strong localization of SPPs eventually emerges at visible regime, which is verified by the exponentially decayed fields and the vanishing autocorrelation function of the SPPs. Physically, the short-range correlated disorder induces strong interference among multiple scattered SPPs and provides an adequate fluctuation to effective permittivity, which leads to the localization effect. Our study demonstrates a unique opportunity for disorder engineering to manipulate light on nanoscale and may achieve various applications in random nanolasing, solar energy, and strong light-matter interactions.

Quasi-phase-matched second harmonic generation of long-range surface plasmon polaritons

In this paper, we experimentally demonstrate the second harmonic generation of long-range surface plasmon polaritons via quasi-phase matching in lithium niobate. After depositing a 9/13 nm thick Au film on periodically poled lithium niobate, TiO2 of about 2.3 μm in thickness is evaporated on the sample as a refractive-index-matching material. This dielectric (periodically poled lithium niobate)-metal(Au)-dielectric(TiO2) sandwich structure can support the transmission of long-range surface plasmon polaritons through it. By designing a moderate ferroelectric domain period of periodically poled lithium niobate, the phase mismatch between the fundamental wave and second harmonic wave of the long-range surface plasmon polaritons can be compensated and a second harmonic wave can be generated effectively. This can be used to provide integrated plasmonic devices with attractive applications in quantum and classic information processing.

Rabi like angular splitting in Surface Plasmon Polariton – Exciton interaction in ATR configuration

We have studied the coupling of propagating Surface Plasmon Polaritons (SPP) on silver films and excitons in CdS quantum dots (QDs). We employed the Kretschmann-Raether configuration of the attenuated total reflection (ATR) to propagate the SPP on silver film of thickness 47.5 nm at three different wavelengths. The CdS QD have been chemically synthesized with particular size such that its exciton of energy would resonate with SPP. High resolution transmission electron microscopy (HRTEM) and scan tunneling microscopy (STM) were used to measure the corresponding QDs size and confirm its shape. Further confirmation of the size has been performed by the effective mass approximation (EMA) model utilizing the band gap of the prepared QDs. The band gaps have been measured through UV–vis absorption spectra as well as scan tunneling spectroscopy (STS). The coupling has been observed as two branching dips in the ATR spectra indicating Rabi like splitting. To the best of our knowledge, this is the first time that Rabi interaction is directly observed in an ATR angular spectra. This observation is attributed to the use a high resolution angular scan (±0.005°), in addition to the Doppler width of the laser line as well as the energy distribution of the excitons. The effect of three different linker molecules (TOPO, HDA), (Pyridine) and (Tri-butylamine) as surface ligands, on SPP-Exciton interaction has been examined.

Ultraslow long-living plasmons with electromagnetically induced transparency.

We analytically examine propagation of surface plasmon polaritons (SPPs) at a thin metallic film between a glass substrate and an electromagnetically induced transparency (EIT) medium. High precision and high resolution in the frequency domain provided by EIT paves the way toward plasmonic group velocities' reduction, even by up to four orders of magnitude, and corresponding lifetime enhancement of SPPs up to microseconds.

Few-Cycle Surface Plasmon Polariton Generation by Rotating Wavefront Pulses

A concept for the efficient generation of surface plasmon polaritons (SPPs) with ultrashort duration close to the single-cycle limit is presented. The scheme is based on grating coupling and laser pulses with wavefront rotation (WFR), so that the resonance condition for SPP excitation is satisfied only for a time window shorter than the driving pulse. The feasibility and robustness of the technique is investigated by means of simulations with realistic parameters. In optimal conditions, we find that a 29.5 fs pulse with an 800 nm wavelength can excite SPPs with <4 fs duration (∼1.5 laser cycles) and a peak field amplitude ∼2.7 times the peak value for the laser pulse.

Plasmonics of magnetic and topological graphene-based nanostructures

AbstractGraphene is a unique material in the study of the fundamental limits of plasmonics. Apart from the ultimate single-layer thickness, its carrier concentration can be tuned by chemical doping or applying an electric field. In this manner, the electrodynamic properties of graphene can be varied from highly conductive to dielectric. Graphene supports strongly confined, propagating surface plasmon polaritons (SPPs) in a broad spectral range from terahertz to mid-infrared frequencies. It also possesses a strong magneto-optical response and thus provides complimentary architectures to conventional magneto-plasmonics based on magneto-optically active metals or dielectrics. Despite a large number of review articles devoted to plasmonic properties and applications of graphene, little is known about graphene magneto-plasmonics and topological effects in graphene-based nanostructures, which represent the main subject of this review. We discuss several strategies to enhance plasmonic effects in topologically distinct closed surface landscapes, i.e. graphene nanotubes, cylindrical nanocavities and toroidal nanostructures. A novel phenomenon of the strongly asymmetric SPP propagation on chiral meta-structures and the fundamental relations between structural and plasmonic topological indices are reviewed.

Fast quantitative optical detection of heat dissipation by surface plasmon polaritons.

Heat management at the nanoscale is an issue of increasing importance. In optoelectronic devices the transport and decay of plasmons contribute to the dissipation of heat. By comparison of experimental data and simulations we demonstrate that it is possible to gain quantitative information about excitation, propagation and decay of surface plasmon polaritons (SPPs) in a thin gold stripe supported by a silicon membrane. The temperature-dependent optical transmissivity of the membrane is used to determine the temperature distribution around the metal stripe with high spatial and temporal resolution. This method is complementary to techniques where the propagation of SPPs is monitored optically, and provides additional information which is not readily accessible by other means. In particular, we demonstrate that the thermal conductivity of the membrane can also be derived from our analysis. The results presented here show the high potential of this tool for heat management studies in nanoscale devices.

Amplification and generation of surface plasmon polaritons in a semiconductor film – dielectric structure

The peculiarities of propagation and amplification of surface waves of plasmon polariton type in a planar semiconductor film – dielectric structure are considered for the THz frequency region, with allowance for dissipation in a semiconductor. Two spectral regions are found, where the group velocity of surface plasmon polaritons is negative. It is shown that in these regions the structure can be considered as an amplifying waveguide with distributed feedback and a high gain with respect to the reflected and transmitted signals. The possibility of generation of electromagnetic radiation in such structures is established.

Generation of surface plasmon-polaritons by edge effects

By using numerical and analytical methods, we describe the generation of fine-scale lateral electromagnetic waves, called surface plasmon-polaritons (SPPs), on atomically thick, metamaterial conducting sheets in two spatial dimensions (2D). Our computations capture the two-scale character of the total field and reveal how each edge of the sheet acts as a source of an SPP that may dominate the diffracted field. We use the finite element method to numerically implement a variational formulation for a weak discontinuity of the tangential magnetic field across a hypersurface. An adaptive, local mesh refinement strategy based on a posteriori error estimators is applied to resolve the pronounced two-scale character of wave propagation and radiation over the metamaterial sheet. We demonstrate by numerical examples how a singular geometry, e.g., sheets with sharp edges, and sharp spatial changes in the associated surface conductivity may significantly influence surface plasmons in nanophotonics.

Plasma modification of spoof plasmon propagation along metamaterial-air interfaces

We report on measurements of the shift in resonance frequency of “spoof” surface plasmon polariton propagation along a 2-D metamaterial slow-wave structure induced by a gaseous plasma near the metamaterial/air interface. A transmission line circuit model for the metamaterial structure interprets the introduction of a plasma as a decrease in unit cell capacitance, causing a shift in the plasmon dispersion to higher frequency. We show through simulations and experiments that the effects of this shift at the resonance frequency and attenuation below and above resonance depend on the plasma density. The shifts recorded experimentally are small owing to the low plasma densities generated near the structure, ∼1011 cm−3, but simulations show that a shift of ∼3% of the resonance frequency can be generated at plasma densities of ∼1012 cm−3.