Excitation Of Surface Plasma Waves Research Articles

Electron acceleration by surface plasma waves in the interaction between femtosecond laser pulses and sharp-edged overdense plasmas

The relativistic acceleration of electrons by the field of surface plasma waves created in the interaction between ultrashort high-intensity laser pulses with sharp-edged overdense plasmas has been investigated. It is shown that the initial phase of the wave experienced by the electrons play a leading part by yielding a well-defined peaked structure in the energy distribution function. This study suggests that resonant excitation of surface plasma waves could result in quasi-monokinetic energetic electron bunches. When the space charge field becomes too strong, this mechanism can evolve toward a true absorption process of the surface wave energy via an enhanced “vacuum heating” mechanism generalized to the case of surface plasma waves.

Excitation of surface plasma waves over metallic surfaces by lasers and electron beams

A laser incident on a metal film (deposited on a glass substrate) from the glass side at a specific angle of incidence, excites a surface plasma wave (SPW) at the metal-free space interface. The ratio of the SPW field to the laser field increases with the laser spot size b attaining a value much greater than one at b>exp(2w/spl alpha//c) where a is the film thickness and /spl omega/ is the laser frequency. The SPW (/spl omega/, k/sub z/,) can also he excited by a relativistic electron beam, propagating parallel to the interface in the free space region, via Cerenkov interaction when beam energy /spl epsiv/b=(|/spl epsiv/|-1)mc/sup 2/ where /spl epsiv/ is the effective metal permittivity, and mc/sup 2/ is the electron rest mass energy. When the surface has a ripple of wave number k/sub 0/, the SPW (/spl omega/, k/sub zz/) can be excited at lower beam energy via sideband coupling, /spl omega/=(k/sub zz/+k/sub 0/)v/sub b/ where v/sub b/z/spl circ/ is the beam velocity. In both cases, however, the positioning of the beam in the close proximity of the interface is required. The scheme is useful for the generation of wavelengths longer than 1 /spl mu/m.

Application of a liquid sensor based on surface plasma wave excitation to distinguish methyl alcohol from ethyl alcohol

A liquid sensor based on surface plasma wave (SPW) exci- tation was fabricated by the deposition of an optimized thickness of gold metal film on a prism. This sensor was applied to measure the reflectivity versus resonant angle of the SPW excitation using water, methyl alcohol, and ethyl alcohol of various concentrations as dielectric. An attempt was also made to theoretically estimate the position of the dip, and the result is in good agreement with experiment. The measured positions of dips, which correspond to the resonant angle of the SPW mode, varied with the species of dielectric, making it easy to distinguish methyl alcohol from ethyl alcohol. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)03701-6)

Theory and modelling of optical waveguide sensors utilising surface plasmon resonance

A theoretical analysis of the phenomenon of excitation of surface plasma waves in integrated-optical waveguide structures is carried out. Rigorous approach to analysis of light propagation through a waveguide structure with a thin metal overlayer supporting surface plasma waves is formulated using a bi-directional mode expansion and propagation method. It is demonstrated that because the back-reflections in the structure are very weak and most of optical power is transmitted by only a limited number of modes of the sensing structure, the method can be considerably simplified.

High-resolution angular and displacement sensing based on the excitation of surface plasma waves

The possibility of building angular and displacement sensors based on the phenomenon of attenuated total reflection (ATR) is explored both numerically and experimentally. ATR occurs when a surface wave is excited by an incoming TM electromagnetic wave through a resonant phase-matching process, as in the Kretschmann coupling scheme. The reflected intensity strongly depends on the angle of incidence of the beam. We first show some computations of the sensitivity and the linearity of an ATR-based sensor, then proceed to the experiment, illustrating how an angular resolution of the order of 0.1 arc sec can be obtained with moderate effort. Finally we show how the sensor, combined with a simple optical arrangement, can be used to detect and measure nanometric displacements, as those provided by piezoelectric actuators.

Model of a chemo-optical sensor based on plasmon excitation in thin silver films

A more realistic theoretical model of a chemo-optical sensor based on the resonant excitation of surface plasma waves a presented here. First, the fundamental sensing configuration, consisting of an optical glass prism, a metal film, a sensing layer and the environmental, is analyzed. Optical parameters of Ag films obtained by our attenuated total reflection (ATR) measurements are employed in this analysis. The optical behaviour of the bromocresol purple sensing layer is simulated using published data. Such a choice of the sensing layer enables this structure to be used for sensing basic vapours in the air. A more general sensing configuration with an added layer is then analysed. For this purpose a new more realistic figure of merit of sensitivity is defined. Some specific features of this configuration are discussed and special attention is given to the utilization of this added layer to increase the sensitivity of the sensor.

Parametric excitation of electromagnetic and surface plasma waves of a ribbon electron beam in a periodic magnetic field

Parametric excitation of electromagnetic and surface plasma waves of a ribbon electron beam in a periodic magnetic field

Surface-Plasma Absorption in Silver Induced by a Granular Dielectric Overcoating

ABSTRACTIt is shown that when transparent dielectric particles are deposited on metallic surfaces, excitation of surface plasma waves (SPW) becomes possible. The coupling of light with SPW is done via mirror-image effects. A drop in reflectance is observed at the resonance frequency in a similar fashion as in surface roughness experiments. Experimental evidence is proved by depositing very thin layers of hafnium oxide as well as tin oxide on silver surfaces.

Optical effects of surface plasma waves with damping in metallic thin films

Effects of optical absorption on surface plasma waves are computed from the Fresnel reflection and transmission coefficients for a metallic thin film. It is shown that the angle of incidence at which the reflectivity exhibits a deep minimum is greater than the angle of incidence at which the H field of the surface plasma wave at the metal-vacuum surface exhibits maximum amplitude. Surface plasma waves can have maximum amplitude at an angle of incidence where reflectivity is near maximum, and a deep minimum in reflectivity can occur without the simultaneous excitation of intense surface plasma waves.

Second harmonic generation due to action of light on a metal surface with a periodic profile

The complete problem of second harmonic generation (SHG) for light incident on a metal surface is reduced to an external electromagnetic problem by generalization of the Leontovich boundary condition. Calculations are made of the SHG intensity on a metal surface having a sinusoidal profile. It is shown that resonance excitation of surface plasma waves on a periodic surface may result in enhancement of SHG by a factor of the order of 106.

INVESTIGATION OF A VERY THIN AND INHOMOGENEOUS FILM OF SiO FROM SURFACE PLASMON OPTICAL EXCITATION

The optical excitation of surface plasma waves is used to characterize a very thin and inhomogeneous film of SiO, the roughness and anisotropy effects being taken into account.

Enhancement of surface and volume photoeffects in cesiated Al thin films by controlled excitation of surface plasma waves at low photon energies

Enhancement of surface and volume photoeffects in cesiated Al thin films by controlled excitation of surface plasma waves at low photon energies

Optical excitation of surface plasma waves in an indium film bounded by dielectric layers

The method of attenuated total reflection (ATR) was used to excite optically surface plasma waves (SPWs) in thin indium films. Three successive layers of MgF 2/In/MgF 2 were evaporated onto the base of a glass prism which had a high refractive index. Continous thin films of indium were obtained by maintaining the substrate at liquid nitrogen temperature during deposition. The ATR angular spectra and associated resonant oscillations were studied at three different wavelengths in the visible region and good agreement was obtained between the experimental and the calculated spectra. The symmetric SPW of the indium film was more highly attenuated than the antisymmetric SPW. Owing to the high damping of the plasma in indium only the antisymmetric SPW could be excited via an optical reflectance resonance when the indium slab was isolated by thick dielectric layers. With thinner bounding dielectrics two SPW-type resonances were observed. Complete calculations of the magnetic field oscillations within the variousmedia, as well as calculations of the current distributions and surface charge densities of the indium film, showed resonant oscillations of mixed symmetry.

Use of surface plasmon excitation for determination of the thickness and optical constants of very thin surface layers

We present a method using attenuated total reflection (ATR) with excitation of surface plasma waves at different wavelengths and angles of incidence, which allows an accurate determination of the thickness and optical constants of absorbing surface layers from optical measurements only. This method is applied to the case of very thin Au surface layers on (111)Ag, and the results are discussed.

Optical excitation of surface plasma waves in layered media

The method of frustrated total reflection is used to optically excite electromagnetic surface plasma waves (SPW) in two different layered structures. The first system studied has two films (Mg${\mathrm{F}}_{2}$-Ag) between glass and air, and the second has three films (Ag-Mg${\mathrm{F}}_{2}$-Ag) between glass and air. Surface roughness of the evaporated Mg${\mathrm{F}}_{2}$ films is found to increase with film thickness and this roughness has a pronounced effect on the SPW resonances. A cermet is imagined to form at the Mg${\mathrm{F}}_{2}$-Ag interface, and its effective optical constants can be evaluated using the Maxwell Garnett theory. If this cermet is treated as a separate layer in the structure, then good agreement is found with the experimentally observed resonances. A calculation of the Poynting vector field, current distributions, and surface charge densities, resulting from an incident monochromatic plane wave, shows the different modes of oscillation corresponding to each resonance.

Spectroscopy of Very thin metal layers on metallic surfaces using optical excitation of surface plasmons

We show how the optical constants of very thin layers deposited on metallic surfaces can be deduced from the modifications of theR p resonances due to excitation of surface plasma waves by the ATR method. The optical constants of discontinuous Au thin layers (thickness <20Å) on Ag surfaces, prepared and studied under ultrahigh vacuum, are determined over the (4000÷6000) Å spectral range.

Optical Surface Plasmon Resonance as a Measurement Tool

Optical excitation of non-radiative surface plasma waves at the interface between a metal and another medium is used for determining certain parameters of the metal or the adjoining substance. Relative variations of observable parameters with variations of the refractive index of silver are compared with ellipsometric data from the literature. Cover layer thickness changes can be observed and variations in the refractive index of the adjacent medium can be discriminated against by recording the position together with the shape of the reflection curve. A measurement technique for the observation of rapid layer growth is reported.

Optical excitation of nonradiative surface plasma waves

physica status solidi (b)Volume 42, Issue 1 p. K37-K39 Short Note Optical excitation of nonradiative surface plasma waves A. Otto, A. Otto Sektion Physik der Universität MünchenSearch for more papers by this author A. Otto, A. Otto Sektion Physik der Universität MünchenSearch for more papers by this author First published: 1970 https://doi.org/10.1002/pssb.19700420155Citations: 28AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume42, Issue11970Pages K37-K39 RelatedInformation

Excitation of nonradiative surface plasma waves in silver by the method of frustrated total reflection

A new method of exciting nonradiative surface plasma waves (SPW) on smooth surfaces, causing also a new phenomena in total reflexion, is described. Since the phase velocity of the SPW at a metal-vacuum surface is smaller than the velocity of light in vacuum, these waves cannot be excited by light striking the surface, provided that this is perfectly smooth. However, if a prism is brought near to the metal vacuum-interface, the SPW can be excited optically by the evanescent wave present in total reflection. The excitation is seen as a strong decrease in reflection for the transverse magnetic light and for a special angle of incidence. The method allows of an accurate evaluation of the dispersion of these waves. The experimental results on a silver-vacuum surface are compared with the theory of metal optics and are found to agree within the errors of the optical constants.