Interference Of Surface Plasmon Waves Research Articles

On Surface Wave Excitation by of Finite-Aperture Light Beams

A rigorous formulation of a theoretical method for investigating reflection of a plane electromagnetic wave from a flat-layered structure in the Kretschmann configuration is presented. Excitation of a surface wave is investigated taking into account diffraction effects caused by the finite aperture of the incident wave. Attention here is paid to application of the developed theory for investigating the Goos–Hanchen effect. Interference of surface plasmon waves upon their excitation on the surface of a metal film is analyzed. Possible applications of the obtained results are discussed.

Optical Manipulation of Dielectric Nanoparticles with Au Micro-racetrack Resonator by Constructive Interference of Surface Plasmon Waves

We design a gold micro-racetrack resonator (Au-MRR) which can tightly trap and drive the dielectric nanoparticle to rotate around the circuit of racetrack with an adjustable velocity. Since the surface plasmon waves can be excited and obey the resonance condition of the Au-MRR, the optics force can be strengthened observably due to the resonance. The optical forces applied on dielectric nanoparticle are discussed by utilizing the Maxwell’s stress tensor integration with a numerical finite element method. The depth of longitudinal trapping potential well in the Au-MRR is four times as large as that of a straight waveguide. At the same level of input power, the velocity of particle with radius of 50 nm driven by optical forces on Au-MRR is 200 times larger than that on a straight waveguide. Further, we explore the motion behavior of single nanoparticle lies on different position of Au-MRR, which can provide the details to trap and manipulate multiple nanoparticles and predict their trace of movement. This optimum geometry of Au-MRR allows further enhancement of the optical forces which is expected to realize all-optical on-chip manipulation of nanoparticles, biomolecules, and many other nanomanipulation applications.

Effect of Pore Thickness and the State of Polarization on the Optical Properties of Hexagonal Nanoarray of Au/Nanoporous Anodic Alumina Membrane

Hexagonal nanoarrays of Au particles were deposited on nanoporous anodic alumina membrane (NAAM) utilizing r.f. magnetron sputtering. The thickness of the NAAMs is adjusted by changing the second anodization time from 5 min to 20 min. The surface morphology, composition, and optical properties are characterized by using SEM, EDX, and spectrophotometer, respectively. The effects of the NAAM thickness and state of polarization on the morphological changes and on the optical properties of the fabricated nanoarrays were addressed. According to the measured optical spectra, the rate of decrease of NAAMs refractive index was found to be 3.825 × 10−4 nm−1. Using the modified Kubelka‐Munk radiative transfer model, the energy gap of NAAMs was calculated from diffused reflectance and was decreased from 1.682 to 1.376 as the anodization time increased from 5 to 20 min. Also, the saturation of interference fringes is substantially enhanced, and field enhancement can be achieved due to the excitation and constructive interference of surface plasmon waves by coating NAAMs with the hexagonal nanoarrays of Au. Based on the advantages of the fabrication approach and the enhanced and controlled properties, this new generation of samples can be used as promising building blocks for nanophotonic and nanoelectronics devices.

Phase study of the generated surface plasmon waves in light transmission through a subwavelength aperture

Interference of surface plasmon (SP) waves plays a key role in light transmission through a subwavelength aperture surrounded by groove structures. In order to characterize interference of the hole and groove-generated SP waves, their phase information was carefully investigated using finite difference time domain simulations. In a structure with only one groove, constructive interference of the generated SP waves will enhance transmitted light by a factor of 5.4 compared with that of a single hole. Increasing the groove number to 3 in the design, which supports constructive interference of SP waves, will enhance the transmission coefficient to 10.5 times that for the single-hole transmission coefficient.

A New Sensor for Heavy Metals Detection in Aqueous Media

A novel technique for rapid and ultrahigh sensing of heavy metals in aqueous media based on microfluidic platform integrated with porous anodic alumina (PAA) membrane and functionalized with ultrathin porous layer of highly ordered hexagonal arrays of Au nanoparticles with 25 nm sub-gaps is proposed. The sensor function is based on both chemical and electromagnetic enhancement. Both were achieved by increasing the number of hot spots and by increasing the density of the Au-nanoparticles at the surface of the PAA membrane up to 7 × 1010 cm-2. The sensor demonstrated high selectivity between three different heavy metal ions ( Hg2+, Cd2+, Pb2+, Cu2+, Co2+, and Ni2+) with concentrations varied from 1 to 20 ppb (1 × 10-3 to 20 × 10-3 μg/ml). The platform provides an instant and fully integrated detection method that is based on in-situ surface-enhanced Raman scattering (SERS) spectroscopy. The observed Raman enhancement is due to the excitation and interference of surface plasmon waves, which are highly dependent on the type and concentration of the heavy metal. Therefore, the proposed sensor is an unprecedented fully integrated platform that is easy to fabricate and seamlessly integrated with an in-situ signal detection device for added functionality.

248 nm imaging photolithography assisted by surface plasmon polariton interference

A new photolithography technique for 248 nm based on the interference of surface plasmon waves is proposed and demonstrated by using computer simulations. The basic structure consists of surface plasmon polariton (SPP) interference mask and multi-layer film superlens. Using the amplification effect of superlens on evanescent wave, the near field SPP interference pattern is imaged to the far field, and then is exposed on photo resist (PR). The simulation results based on finite difference time domain (FDTD) method show that the full width at half maximum (FWHM) of the interference pattern is about 19 nm when the p-polarization light from 248 nm source is vertically incident to the structure. Meanwhile, the focal depth is 150 nm for negative PR and 60 nm for positive PR, which is much greater than that in usual SPP photolithography.

Optical Properties of Porous Anodic Alumina Membrane Uniformly Decorated with Ultra-Thin Porous Gold Nanoparticles Arrays

In this paper, we directly develop a facile method to decorate a modified porous anodic alumina membrane (PAA) with an ultrathin porous film of gold nanoparticles with sub-gaps less than 25 nm and particle size less than 40 nm on the top surface and Au nanoparticles uniformly attached to the pore walls as well as the bottom of the pores, utilizing radio-frequency magnetron sputtering. The size as well as the interparticle distance of the gold nanostructures is adjusted by changing the structural properties of PAA membrane and the sputtering time. According to the measured reflection spectra, the saturation of interference color is significantly enhanced. As a result, the Au-coated PAA membrane exhibits a brilliant and tunable color. Field enhancement can be achieved in these structures through the excitation and constructive interference of surface plasmon waves. In addition, the role of localized surface plasmon and propagating surface plasmon was discussed. A four-layered model is presented to describe the reflectance data that show excellent agreement with the experimental data. The brilliant Au-coated PAA membrane is useful for decorative purposes and holds promise as an effective surface enhanced Raman scattering (SERS) substrate.

Surface plasmon interference pattern on the surface of a silver-clad planar waveguide as a sub-micron lithography tool

A new sub-micron photolithography tool has been realized by utilizing the interference of surface plasmon waves (SPWs) on the near surface of a silver (Ag)-clad ultraviolet (UV) planar waveguide. A laser beam with a wavelength of 325 nm was incident into the waveguide core, and suffered a series of total internal reflections on the interfaces between the waveguide core and the cladding layers. The incident light and the reflected light induced two beams of SPWs traveling in contrary directions, which interfered with each other and formed a standing wave as a sub-micron photolithography tool. A near-field scanning optical microscope (NSOM) was employed to measure the intensity distribution of the stationary wave field of the near surface of the Ag layer of the waveguide, anastomosed with theoretical values acquired by use of finite difference time domain (FDTD) simulations. And with this sub-micron photolithography tool a SMG with a period of 79.3 nm, in good agreement with the theoretical value of 80.1 nm, was inscribed on the surface of a self-processing hybrid SiO2/ZrO2 solgel film for the first time.

Overview of the Characteristics of Micro- and Nano-Structured Surface Plasmon Resonance Sensors

The performance of bio-chemical sensing devices has been greatly improved by the development of surface plasmon resonance (SPR) based sensors. Advancements in micro- and nano-fabrication technologies have led to a variety of structures in SPR sensing systems being proposed. In this review, SPR sensors (from typical Kretschmann prism configurations to fiber sensor schemes) with micro- or nano-structures for local light field enhancement, extraordinary optical transmission, interference of surface plasmon waves, plasmonic cavities, etc. are discussed. We summarize and compare their performances and present guidelines for the design of SPR sensors.

Surface plasmon interference on the surface of an aluminum-covered fiber core array for solgel fabrication of submicrometer gratings

An interesting method to fabricate submicrometer gratings (SMGs) utilizing the interference of surface plasmon waves (SPWs) is presented. The stationary wave field off the aluminum (Al) layer surface of an Al-covered UV fiber core, formed by the interference of the induced SPWs, has been employed as a submicrometer photolithography tool to inscribe SMGs on the surface of a self-processing hybrid HfO(2)/SiO(2) solgel film. Using atomic force microscopy, the period of the fabricated SMGs was measured as 105 nm. The intensity distribution of the stationary wave field was measured by a near-field scanning optical microscope and anastomosed with theoretical values calculated by using FDTD simulations.

Realization of an evanescent Bessel beam via surface plasmon interference excited by a radially polarized beam

We report the experimental confirmation of the evanescent Bessel beam generation via surface plamson resonance excitation with a radially polarized beam. The interference of surface plasmon waves excited by a radially polarized beam creates an evanescent Bessel beam with enhanced localized field and spot size beyond the diffraction limit. The excitation of the surface plasmon is confirmed by the observation of a narrow dark ring at the back focal plane. Two-dimensional intensity distributions at different distances from the sample surface are mapped by a collection-mode near-field scanning optical microscope to verify the nondiffracting and decaying natures of the evanescent Bessel beam.

Interference of Surface Plasmon Waves and Plasmon Coupled Waveguide Modes for the Patterning of Thin Film

We analyze and propose a thin-film patterning method based on Kretschmann's attenuated total reflection (ATR) configuration where the surface plasmon mode and plasmon coupled waveguide modes coupled into a target photosensitive layer are generated. By analyzing stratified media with the help of extended transfer matrix method, we numerically visualize electromagnetic fields of surface plasmon waves and plasmon coupled waveguide modes. Through the interference of these modes, it is to be shown that our proposed configuration can be used in the optical lithography, especially for the thin-film patterning methods. Feasibility is tested by coating a dielectric layer on the gold layer in the ATR configuration.

Periodic modulation of extraordinary optical transmission through subwavelength hole arrays using surrounding Bragg mirrors

The enhanced light transmission through an array of subwavelength holes surrounded by Bragg mirrors is studied, showing that the mirrors act to confine the surface plasmons associated with the extraordinary optical transmission effect, forming a surface resonant cavity. The overall effect is increased light transmission intensity by more than a factor of 3 beyond the already enhanced transmission, independent of whether the Bragg mirrors are on the input or the output side of the incident light. The geometry of the Bragg mirror structures controls the enhancement and can even reduce the transmission by half. By varying these geometric parameters, we were able to periodically modulate the transmission of light for specific wavelengths, consistent with the propagation and interference of surface plasmon waves in a resonant cavity. Finite difference time domain simulations and a wave propagation model verify this effect.

Surface Plasmon Interference Nanolithography

A new nanophotolithography technique based on the interference of surface plasmon waves is proposed and demonstrated by using computer simulations. The wavelengths of the surface plasmon waves at metal and dielectric interfaces can reach the nanometer scale while their frequencies remain in the optical range. As a result, the resolution of this surface plasmon interference nanolithography (SPIN) can go far beyond the free-space diffraction limit of the light. Simulation results show that one-dimensional and two-dimensional periodical structures of 40-100 nm features can be patterned using interfering surface plasmons launched by 1D gratings. Detailed characteristics of SPIN such as field distribution and contrast are also investigated.