Query: Phase matching conditions of surface plasmons

title: Surface plasmons coupled two dimensional photonic crystal biosensors for Epstein Barr virus protein detection
abstract: The fundamental detection scheme of typical grating or photonic crystal (PhC) sensors relies on the correlation of the diffraction behaviors with the refractive index of target analyte. For biomaterial detection, a thin gold film is usually deposited on the sensor surface so that cross linkers can be anchored before functionalizing the device. The nanoscale metallic film suggests plasmonic resonances play a critical role in light matter interaction. In this work, we demonstrated a compact two dimensional (2D) hexagonal PhC biosensor with thin gold film coating. In such a device, surface plasmon polariton (SPP) on the metal structure and phase matching of optical wave with the PhC are considered when analyzing light biomaterial interaction on the detector. Using Epstein Barr nuclear antigen 1 (EBNA 1) antibody as an example, protein sensing along different lattice orientations of the PhC biosensor was investigated. Based on the dispersion relationship and phase matching conditions, we unravel the mechanisms involved in the wavelength shifts and sensitivities. The simulation results verify the phenomenon of tighter spatial confinement and higher local field intensity from the SPP, which helps detecting small variations of the refractive index on the sensor surface.

title: Laser Raman scattering by graphene plasmons
abstract: A new scheme of Raman scattering of a laser by THz graphene plasmons in the presence of both space charge and electromagnetic surface plasmons is proposed. Plasmon laser coupling arises through the two dimensional response of electrons in graphene. For optical frequency laser scattering by THz plasmons, phase matching conditions are satisfied for near normal incidence and the Raman scattered wave also propagates normal to the graphene surface. The amplitude of the electric field of the Raman scattered wave scales linearly with the plasmon density fluctuation level and laser amplitude and inversely with the electron effective mass. Raman scattering would provide in situ diagnostics of the amplitude and frequency of the THz wave.

title: Application of graphene second order nonlinearity in THz plasmons excitation
abstract: In this paper, the phase matching condition, the excited electric field formula, and the nonlinear susceptibility tensor elements conditions required for excitation of surface plasmon polaritons (SPPs) on flat graphene are derived. The second order nonlinearity is utilized for compensation of the free space and SPPs wave vectors mismatch. In order to excite SPPs on graphene, the phase matching condition is investigated for the second order effects including the difference frequency generation (DFG) the second harmonic generation (SHG) and the sum frequency generation (SFG) In addition, since the incident waves polarizations play an important role in the excitation of the SPPs, the realization of the susceptibility tensor elements conditions, the effect of TE, TM, not polarized and perpendicularly polarized incident waves are investigated using the Green's function theory.

title: Hybrid stimulated Raman scattering two plasmon decay instability and 3/2 harmonic in steep gradient femtosecond plasmas.
abstract: We numerically study interaction of a very intense (I~10^{17} to 5x10^{19}W/cm^{2} femtosecond obliquely incident p polarized laser pulse with a steep gradient (L~l) plasma, i.e. within the conditions typical for modern experiments. It is shown that the hybrid stimulated Raman scattering two plasmon decay instability develops near the quarter critical density surface and plays the dominant role for the plasma waves' excitation and energy absorption. The plasmons are excited as two wave packets confined near this surface with very wide o_{0}/c spatial spectra along its normal. Hence, phase matching conditions for the 3/2 harmonic generation are fulfilled immediately and include the mechanism coming from the high harmonics of plasma waves. This mechanism has been proved experimentally by observing an additional 3/2 harmonic beam.

title: Directional Plasmonic Excitation by Helical Nanotips
abstract: The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, like a nanoparticle or a nanohole, the coupling between a broadband effect, i.e. scattering, and a discrete one such as surface plasmon excitation, leads to Fano like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light plasmon coupling and to achieve a directional plasmonic excitation. Here we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin dependent azimuthal variation. This effect can be described by a Fano like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of the nanostructure.

title: Directional Plasmonic Excitation by Helical Nanotips
abstract: The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a nanoparticle or a nanohole, the coupling between a broadband effect, i.e. scattering, and a discrete one, such as surface plasmon excitation, leads to Fano like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light plasmon coupling and to achieve a directional plasmonic excitation. Here, we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin dependent azimuthal variation. This effect can be described by a Fano like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of the nanostructure.

title: Design and experimental investigation of a chiral plasmonic nanotaper
abstract: The phenomena of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, like a nanoparticle or a nanohole, the coupling between a broadband effect, i.e. scattering, and a discrete one such as surface plasmon excitation, leads to Fano like plasmonic resonance line shapes. The necessary phase matching requirements can be used to engineer the light plasmon coupling and to achieve a directional plasmonic excitation. Here we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin dependent azimuthal variation. This effect can be described by a Fano like interference with a complex coupling factor that can be modified thanks to a symmetry breaking nanostructure.

title: Collective oscillations of twin boundaries in high temperature superconductors as an acoustic analogue of two dimensional plasmons.
abstract: Low frequency collective oscillations in a superlattice consisting of alternating highly anisotropic layers are considered. Such superstructure may be formed in the ferroelastic near the structural phase transition by alternation of twins. For the surface waves, propagating along the layers, the conditions and the range of existence of those with the dispersion law \ensuremath{\omega}\ensuremath{\sim}\mathit{k}{1/2} characteristic for two dimensional plasmons, have been analyzed for a solid state system with consideration for elastic anisotropy and retardation of acoustic waves. Such excitations `dyadons' were used by Horovitz, Barsch, and Krumhansl [ (1987) in an attempt to explain the anomalies of low temperature thermodynamic and kinetic characteristics of high \mathit{T}}_{\mathit{c} superconductors. We have shown that the similarity of the densities of the matching phases and the retardation of elastic waves in the crystal narrow the range of existence of dyadons, but the high elastic anisotropy of the solid phases enlarges the range of existence of such excitations in solid state systems. An example of possible crystalline geometry of the phase matching, for which there arise collective excitations of the type under consideration, is found. For transverse and longitudinal waves propagating across the layers, the existence is proved of low frequency acoustic branches separated by a wide gap from the nearest optical branches.

title: Surface plasmon polarization filtering in a single mode dielectric waveguide.
abstract: We demonstrate that metallic electrodes symmetrically placed about a single mode dielectric waveguide can effectively polarize the mode by excitation of surface plasmons. The transmission through the metal electrode waveguide structure is examined as a function of mode polarization and electrode spacing. It is found that modes polarized perpendicular to the metal surface can resonantly excite surface plasmons, extinguishing the mode in the waveguide core, while modes polarized parallel to metal surface only suffer mode attenuation due to the presence of the metal. The phase matching conditions for excitation of surface plasmons are examined and the polarization and insertion loss of the transmitted mode is experimentally verified.

title: Magnetoplasmonic crystals based on commercial digital discs
abstract: Transversal magneto optical Kerr effect (TKE) controlled by surface plasmon polariton resonances is studied in nickel and combined silver/nickel magnetoplasmonic crystals fabricated on the base of commercial digital discs with periods of 320 nm, 740 nm, and 1500 nm. Wood's anomaly is observed in visible and near IR spectral ranges due to fulfilment of phase matching conditions between surface plasmons and 1, 2, and +1 diffraction orders for the samples with these periods, respectively. Strong asymmetrical Fano shape resonances are observed in TKE spectra in the vicinity of surface plasmons' resonances.