Long-range Surface Plasmon Polariton Research Articles

Compact Z-add-drop wavelength filters for long-range surface plasmon polaritons

We design, fabricate and investigate compact Z-add-drop (ZAD) filters for long-range surface plasmon polaritons (LR-SPPs) at telecom wavelengths. The ZAD filter for LR-SPPs consists of two ridge gratings formed by periodic gold thickness modulation at the intersections of three zigzag-crossed gold stripes embedded in polymer. We investigate influence of the grating length and crossing angle on the filter characteristics and demonstrate a 10 masculine- ZAD filter based on 80-microm-long gratings that exhibit a 15-dB dip (centered at ~ 1.55 microm) in transmission of the direct arm along with the corresponding ~ 13-nm-wide transmission peak in the drop arm.

In-line extinction modulator based on long-range surface plasmon polaritons

We develop thermo-optic in-line extinction modulators (ILEMs) whose operation is based on the guiding of long-range surface plasmon polaritons (LRSPPs) along metal stripes embedded in polymer and heated by electrical signal currents. Several 1 cm long ILEMs, which utilize 15 nm thin and 8 μm wide gold stripes guiding LRSPPs and comprising 3–6 mm long control electrodes, are investigated at telecom wavelengths. The fabricated ILEMs feature low driving powers (∼100 mW) and high extinction ratios (∼30 dB) that depend weakly on the wavelength, moderate response times (∼0.5 ms) and the total (fiber-to-fiber) insertion loss of ∼8 dB when using single-mode fibers.

Experimental evaluation of reflectance of surface plasmon polaritons at metal step barrier

We have proposed a way to evaluate the reflectance of surface plasmon polaritons (SPP) at a Ag step barrier from an experiment using the attenuated total reflection structure consisting of ultra-thin metal films sandwiched by dielectrics with nearly identical refractive index. At a wavelength of 632.8 nm, for a long-range SPP (L-SPP) excited in a Ag film of 5.7 nm in thickness, the reflectance at Ag step barriers of 766 nm in height was evaluated to be 7.9 × 10 −2.

Observation of Resonant Photon Tunneling in Photonic Double Barrier Structures

Reflectance and transmittance of 632.8 nm He-Ne laser light for photonic double barrier structures (consisting of a SF10 prism, SiO2 layer, Al or Al2O3 active layer, SiO2 layer and SF10 prism) were measured as a function of the angle of incidence for both the ρ- and s-polarized incidence. Sharp reflection dips and transmission peaks were observed at angles larger than the critical angle of total reflection. The appearance of the transmission peaks can be attributed to resonant photon tunneling through the photonic double barrier structures analogous to resonant electron tunneling through double potential barrier structures. Resonant tunneling is mediated by the long-range surface plasmon polariton in the case of the Al active layer and the electromagnetic guided modes in the case of the Al2O3 layer.

Surface plasmon–polariton waves guided by thin metal films

Surface plasmon-polariton modes supported by thin metal films surrounded by dissimilar semi-infinite dielectrics are studied. The dispersion of the modes is evaluated, and their characteristics are investigated when the metal film thickness and the superstrate refractive index are varied. Long-range surface plasmon-polaritons are shown to be supported even by highly asymmetric configurations.

An Improved Virtual Mode Theory of ATR Experiments on Surface Polaritons. Application to Long‐Range Surface Plasmon‐Polaritons in Asymmetric Layer Structures

AbstractThe damping properties of surface polaritons, especially long‐range surface plasmon‐polaritons (LRSP) in asymmetric layer structures are analyzed taking into account the presence of a coupling prism. Both, the response treatment to calculate attenuated‐total‐reflection (ATR) spectra and the virtual mode treatment are used. Two different types of virtual modes are analyzed. One of them describes the propagation properties of the surface polariton in the presence of both intrinsic and radiative damping. The other type describes a surface polariton with a driving field and hence this mode allows to find out the optimum conditions for the ATR experiment. These two modes are investigated in detail and the results of the numerical calculation are presented in graphical form. The results for the ATR configuration show that in asymmetric embedded silver layers the propagation length exceeds the value for the symmetric embedded one significantly.

Long-range surface plasmon-polaritons in asymmetric layer structures

We analyze the effect of asymmetric embedding of thin silver layers on the propagation length and the power flow distribution of long-range surface plasmon-polaritons (LRSP). We show that in such configurations LRSP can achieve propagation length which exceeds the value for the symmetric case by up to 3 orders of magnitude.

Characteristics of Long-Range Surface Plasmon Polaritons Excited be Fundamental Gaussian Beam

The angular spread of fundamental Gaussian beam is comparable to the half-width of angle-scanned ATR spectra of long-range surface plasmon polaritons (L–SP's). By taking into account such a beam divergence, we therefore investigate characteristics of L–SP's excited by the fundamental Gaussian beam and present numerical results on the ATR spectra and spatial profiles of reflected light intensity.

Spatial dependence of reflected light intensity in ATR geometry: Long-range surface plasmon polariton case

The spatial dependence of the reflected light intensity has been experimentally observed by investigating the geometry of the prism/matching oil/Ag film/Pyrex glass, in which one can excite the so-called long-range surface plasmon polaritons. The experimental and the theoretical results are in fair agreement.

Optical second harmonic generation by long-range surface plasmon polaritons excited by a finite 1-D beam

Second harmonic generation of long-range surface plasmon polaritons excited by a finite 1-D beam are discussed. To simplify the analysis of second harmonic generation, we adopt the “pole cancellation” method originally developed by Sipe. A numerical calculation of second harmonic intensity is presented. It is found that the effect of beam size on second harmonic intensity should be taken into account in actual experiments.

Experimental Observation of Long-Range Surface Plasmon Polaritons

ATR technique (glass prism-index matching oil-Ag-CaF 2 single crystal) has been used to observe long-range surface plasmon polaritons discussed recently by Sarid. At 632.8 nm, we have successfully observed the sturface plasmon polaritons in the propagation distance of 105 µm.

Experimental observation of the long-range surface-plasmon polariton

The propagation and attenuation constants of long-range surface-plasmon polaritons propagating on thin metal films have been measured for several film thicknesses by using a hemispherical retroreflecting coupler. The results are in agreement with our theoretical dispersion curves, which predict that the attenuation constant of this mode can decrease by a factor of 63 relative to that obtained with a thick metal film.