Search results for "Near and far field"

Design, near-field characterization, and modeling of 45 circle surface-plasmon Bragg mirrors

2006

The development of surface plasmon polariton (SPP) optical elements is mandatory in order to achieve surface plasmon based photonics. A current approach to reach this goal is to take advantage of the interaction of SPP with defects and design elements obtained by the micro- or nano-structuration of the metal film. In this work, we have performed a detailed study of the performance and behavior of SPP-Bragg mirrors, designed for 45\ifmmode^\circ\else\textdegree\fi{} incidence, based on this approach. Mirrors consisting of gratings of both metal ridges on the metal surface and grooves engraved in the metal, fabricated by means of electron beam lithography and focused ion beam, have been consi…

Antenna Tapering Strategy for Near-Field Enhancement Optimization in Terahertz Gold Nanocavities

2019

Plasmonic nanoantennas (NAs) have received a growing attention in recent years due to their ability to confine light on sub-wavelength dimensions [1]. More recently, this property has been exploited in the terahertz (THz) frequency range (0.1–10 THz) for enhanced sensing and spectroscopy [2], as well as for more fundamental investigations [3]. These applications typically require high local electric fields that can be achieved by concentrating THz radiation into deeply sub-wavelength volumes located at the NAs extremities. However, the achievable near-field enhancement values are severely limited by the poor resonance quality factor of traditional rod-shaped THz NAs. Unlike what is commonly…

Near-field probing of active photonic-crystal structures

2002

We report a study of the optical near field of an active integrated component operating near the 1.55-mum telecommunications wavelength. The device is based on a two-dimensional photonic crystal etched in a suspended InP membrane. Topographic as well as optical information is collected by use of a scanning near-field optical microscope in collection mode, providing information about the local distribution of the losses.

Near-Field Distribution of Optical Transmission of Periodic Subwavelength Holes in a Metal Film

2000

Recent experimental discovery of the enhanced optical transmission through metal films with periodic subwavelength holes has given rise to a considerable interest in the optical properties of such structures due to their possible numerous applications in optics and optoelectronics as well as rich physics behind the phenomenon of the transmission enhancement [1–4]. The transmission of a subwavelength aperture is very low and proportional to the fourth power of the ratio of its diameter and light wavelength. However, if a metal film is perforated with a periodic array of such holes, the optical transmission can be significantly enhanced [1]. Being normalized to the total area of the illuminat…

Scanning near-field optical microscopy (SNOM) of lithium niobate aperiodically poled during growth

2007

In the present work, aperiodically poled lithium niobate (APPLN) was grown, along the a-axis, by the off-centred Czochraski method. The domain formation has been triggered by rare earth doping, using in this case Er3+ and Yb3+ ions. The growth conditions were selected in order to obtain a modulated domain distribution. SNOM measurements have been performed with a Nanonics Imaging Ltd model MultiView 200 TM working in non-contact tapping mode.

Multi-frequency near-field enhancement with graphene-coated nano-disk homo-dimers.

2019

In this paper, a 3D sub-wavelength graphene-coated nano-disk dimer (GDD) is proposed for multi-frequency giant near-field enhancement. We observed that the dual-band operation originates from the excitation of hybridized localized surface plasmons on top and bottom faces of the disks along with the mutual coupling from the adjacent particle. Due to the sub-wavelength nature of the disks, the excited localized surface plasmons on the sidewalls are weak but they still can affect the dual operating bands. On the other hand, the strength and resonance frequency of the enhanced fields can be simply modulated by tuning the relative distances of 2D graphene disks on top and bottom faces. Adjustabl…

DEVELOPMENT AND NEAR-FIELD CHARACTERIZATION OF SURFACE PLASMON WAVEGUIDES

2007

Local excitation of surface plasmon polaritons at discontinuities of a metal film: Theoretical analysis and optical near-field measurements

2002

Nonresonant excitation of surface plasmon polaritons at discontinuities of a gold film is numerically studied and experimentally observed with scanning near-field optical microscopy. It is shown that surface polaritons can be effectively launched at the edges of a metal film illuminated at an angle of incidence greater than the resonant angle of surface polariton excitation. The electromagnetic near-field distribution over a thin metal film exhibits significantly different features under resonant and nonresonant excitations due to different surface polariton excitation mechanisms. In the latter case the field distribution is determined by the interference of the excitation light and surface…

NEAR-FIELD OPTICAL EXCITATION AND DETECTION OF SURFACE PLASMONS

2007

Theory of Near‐field Optical Imaging with a Single Molecule as Light Source

2002

Scanning near-field optical microscopes (SNOM) illuminate a sample in the very near-field using a nanometer sized tip. Ideally, the light source should be point-like and many efforts have been made to optimize tip efficiency (see, for example, the article of Heimel et al in this issue). Very recently, Sandoghdar et al have realized a molecular probe tip in which a terrylene molecule inserted in a paraterphenyl microcrystal is attached at the extremity of the probe tip [1]. The excited molecule behaves as a point-like light source which is raster scanned over an aluminium patterned structure. We propose here an analysis of this experiment based on the field-susceptibility formalism (also cal…