Showing papers in "Journal of Optics in 2005"
TL;DR: In this article, the existence of surface electromagnetic modes in corrugated surfaces of perfect conductors was explored and it was shown that these structures support surface bound states and that the dispersions of these modes have strong similarities with the dispersion of surface plasmon polariton bands of real metals.
Abstract: In this paper we explore the existence of surface electromagnetic modes in corrugated surfaces of perfect conductors. We analyse two cases: one-dimensional arrays of grooves and two-dimensional arrays of holes. In both cases we find that these structures support surface bound states and that the dispersions of these modes have strong similarities with the dispersion of the surface plasmon polariton bands of real metals. Importantly, the dispersion relation of these surface states is mainly dictated by the geometry of the grooves or holes and these results open the possibility of tailoring the properties of these modes by just tuning the geometrical parameters of the surface.
924 citations
TL;DR: In this article, the authors studied the impact of localized surface plasmon (LSP) modes of individual apertures on the transmission peaks associated with the periodic arrays of hole arrays.
Abstract: After reviewing the present understanding of the transmission properties of single apertures and the enhanced transmission through hole arrays, experimental results are presented which show how localized surface plasmon (LSP) modes of individual apertures contribute to the transmission peaks associated with the periodic arrays. In particular, it is shown that the surface plasmon polaritons (SPPs) of the periodic structure dominate the spectral signature of the arrays. The results also indicate that the LSP of each hole can interact and that this can be controlled by appropriate arrangement of the apertures in the array.
373 citations
TL;DR: In this article, proper orthogonal decomposition (POD) was applied to the modal vibration analysis of a metal plate, which was subject to vibrations with an electrodynamical shaker in a range of frequencies from 100 to 5000 Hz.
Abstract: The proper orthogonal decomposition (POD), also known as Karhunen–Loeve expansion, is applied to the modal vibration analysis of a metal plate. The metal plate was subject to vibrations with an electrodynamical shaker in a range of frequencies from 100 to 5000 Hz. The data were obtained from the measurements with a laser vibrometer. The plate vibration measurements were used to calculate the eigenfunctions and the eigenvalues. It was found that a large fraction of the total energy of the vibrations is contained within the first four POD modes. The essential features of the vibrations are thus described by only the first four eigenfunctions.
364 citations
TL;DR: In this article, a model for calculating the time necessary for filling one or more specific holes in a photonic crystal fiber is made, which is verified for water and its enabling potential is illustrated by a polymer application.
Abstract: A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre is demonstrated for a polymer and for water. Launching light into such a hybrid-material core proves to be very easily done. Finally, a scheme for enabling access to the core alone, by use of a fusion splicer, is presented.
211 citations
TL;DR: In this paper, the authors studied the transmission properties of left-handed metamaterials and arrays of split-ring resonators (SRRs) and examined the dependence of the transmission through single-and double-ring SRRs on parameters of the system such as the size and shape of the SRRs, size of the unit cell, dielectric properties of the embedding medium where the SRR reside, and SRR orientation relative to the incoming electromagnetic field.
Abstract: Using numerical simulation techniques such as the transfer matrix method and the commercially available code Microwave Studio, we study the transmission properties of left-handed (LH) metamaterials and arrays of split-ring resonators (SRRs). We examine the dependence of the transmission through single- and double-ring SRRs on parameters of the system such as the size and shape of the SRRs, size of the unit cell, dielectric properties of the embedding medium where the SRRs reside, and SRR orientation relative to the incoming electromagnetic field. Moreover, we discuss the role of SRRs and wires on the electric cut-off frequency of the combined system of wires and SRRs, as well as the influence of the various system parameters on the LH transmission peak of a medium composed of SRRs and wires. Finally, demonstrating the disadvantages of the currently used SRR designs due to the lack of symmetry, we discuss more symmetric, multigap SRRs, which constitute very promising components for future two-dimensional and three-dimensional LH structures.
135 citations
TL;DR: In this article, a method of generating an electromagnetic Gaussian Schell-model source from two coherent linearly polarized plane waves is described, which involves two mutually correlated phase-only liquid-crystal spatial light modulators placed in the arms of a Mach-Zehnder interferometer.
Abstract: A method of generating an electromagnetic Gaussian Schell-model source from two coherent linearly polarized plane waves is described. This method involves two mutually correlated phase-only liquid-crystal spatial light modulators placed in the arms of a Mach–Zehnder interferometer. The sources produced by this method can be used to generate a wide class of electromagnetic beams with prescribed coherence and polarization properties.
130 citations
TL;DR: Wang et al. as mentioned in this paper proposed an integrated light-guide plate (LGP) based on micro-prism structures by using traditional transparent polymethyl methacrylate (PMMA) material, which can be designed to control the illumination angle, and to get high uniformity of intensity.
Abstract: A conventional LCD backlight system is composed of light sources, a light-guide plate (LGP) and optical sheets, such as reflection sheets, diffusion sheets and prism sheets, etc. In order to make the backlight system thinner and brighter, we propose a novel integrated LGP based on micro-prism structures by using traditional transparent polymethyl methacrylate (PMMA) material, which can be designed to control the illumination angle, and to get high uniformity of intensity. So the backlight system will be simplified to use only one LGP and to require no other optical sheets. By using the Monte Carlo ray tracing method, the light scattering phenomenon inside the LGP is analysed. The illumination angle with forward directivity and sufficient intensity uniformity are optimized with the simulation program. Design results reveal that our LGPs can achieve a uniformity of intensity better than 86%, and get a peak illumination angle from +40? to ?20?, without using any optical sheets. Design examples, including 1.8?inch LGPs and 14.1?inch LGPs, are also performed.
117 citations
TL;DR: In this article, the angular momentum of a light beam can be changed by passage through a slab of crystal, which can have both orbital (Jorb) and spin (Jsp) contributions, which are calculated paraxially exactly for arbitrary biaxiality and chirality.
Abstract: The angular momentum Jinc of a light beam can be changed by passage through a slab of crystal. When the beam is incident along the optic axis of a biaxial crystal, which may also possess optical activity (chirality), the final angular momentum J can have both orbital (Jorb) and spin (Jsp) contributions, which we calculate paraxially exactly for arbitrary biaxiality and chirality and initially uniformly polarized beams with circular symmetry. For the familiar special case of a non-chiral crystal with fully developed conical-refraction rings, J is purely orbital and equal to Jinc/2, reflecting an interesting singularity structure in the beam. Explicit formulas and numerical computations are presented for a Gaussian incident beam. The change in angular momentum results in a torque on the crystal, along the axis of the incident beam. An additional, much larger, torque, about an axis lying in the slab, arises from the offset of the cone of conical refraction relative to the incident beam.
115 citations
TL;DR: In this paper, the optical response of isolated nanowires, double-wire systems, and Π-structures is compared in terms of their electric and magnetic dipole moments, and it is shown that both dielectric permittivity and magnetic permeability can be negative at optical and near infrared frequencies.
Abstract: We compare the optical response of isolated nanowires, double-wire systems, and Π-structures, and show that their radiation is well described in terms of their electric and magnetic dipole moments. We also show that both dielectric permittivity and magnetic permeability can be negative at optical and near infrared frequencies, and demonstrate the connection between the geometry of the system and its resonance characteristics. We conclude that plasmonic nanowires can be employed for novel negative-index materials. Finally, we demonstrate that it is possible to construct a nanowire-based 'transparent nanoresonator' with dramatically enhanced intensity and metal concentration below 5%.
105 citations
TL;DR: In this article, the formation and evolution of the far-field patterns of the Gaussian beams passing through a thin self-focusing medium was studied using the Fresnel-Kirchhoff diffraction theory.
Abstract: The formation and the evolution of the far-field patterns of the Gaussian beams passing through a thin self-focusing medium and a thin self-defocusing medium are studied using the Fresnel–Kirchhoff diffraction theory, and the effects of the different Kerr media and the different Gaussian beams on the far-field pattern formation and evolution are analysed by taking into consideration both the change in the additional phase shift induced by the refractive index and the change in the sign of the radius of wavefront curvature of the laser beam passing through the nonlinear medium. Our results show that, when either the divergent Gaussian beam passes through the self-defocusing medium or the convergent Gaussian beam passes through the self-focusing medium, the far-field intensity distribution pattern is a series of thick diffraction rings with a central dark spot; while, when either the divergent Gaussian beam traverses the self-focusing medium or the convergent Gaussian beam traverses the self-defocusing medium, the far-field intensity distribution pattern is a series of thin diffraction rings with a central bright spot. Our results also show that whether the central dark spot or the central bright spot occurs depends mainly on the sign of the product of the additional phase shift and the radius of the wavefront curvature. When the sign is negative, that is, when the divergent Gaussian beam passes through the self-defocusing media, or the convergent Gaussian beam passes through the self-focusing media, the central dark spot surrounded by the thick diffraction rings will emerge in the far field; while, when the sign is positive, that is, when the divergent Gaussian beam traverses the self-focusing media, or the convergent Gaussian beam passes through the self-defocusing media, the central bright spot with the thin diffraction rings will occur in the far field. The difference between the diffraction patterns is attributed to the interplay of the strong spatial self-phase modulation caused by the refractive index change of the medium and the changes in sign of the radius of the wavefront curvature of the incident Gaussian beam. The results obtained in this paper are of significance to the design of practical nonlinear optical limiters for the eye or sensor protection and many other applications.
99 citations
TL;DR: In this paper, the authors identify a surface-plasmon-polariton (SPP) mode and show that its near field possesses a hybrid character, gathering collective and localized effects which are both essential for the transmission.
Abstract: Recent works have dealt with the optical transmission on arrays of subwavelength holes perforated in a thick metallic film. We have performed simulations which quantitatively agree with experimental results and which unambiguously provide evidence that the extraordinary transmission is due to the excitation of a surface-plasmon-polariton (SPP) mode on the metallic film interfaces. We identify this SPP mode and show that its near field possesses a hybrid character, gathering collective and localized effects which are both essential for the transmission.
TL;DR: In this paper, the second-harmonic signal peaks at incidence angles corresponding to enhanced transmission of the fundamental beam of 800 nm wavelength except at small incidence angles where the local symmetry minimizes the effective second-order nonlinear susceptibility of the apertures.
Abstract: We demonstrate the generation of second-harmonic radiation in transmission through periodic and disordered arrays of sub-wavelength metallic apertures. For circular apertures in a square lattice, the second-harmonic signal peaks at incidence angles corresponding to enhanced transmission of the fundamental beam of 800 nm wavelength except at small incidence angles where the local symmetry minimizes the effective second-order nonlinear susceptibility of the apertures. Even though the linear transmission of the fundamental beam can be more than five times greater through the periodic array as compared to a disordered array, the strength of the second harmonic from the disordered array is greater at large incidence angles. By breaking the local symmetry through the use of apertures of non-centrosymmetric shape, the second-harmonic output occurs at fundamental transmission resonances at small incidence angles.
TL;DR: A review of studies of the nonlinear refraction and nonlinear absorption of semiconductors, fullerenes, dyes, metals, crystals, and liquids (bulk samples, suspensions, solutions, embedded nanoparticles, and thin films) is presented in this paper.
Abstract: A review of studies of the nonlinear refraction and nonlinear absorption of semiconductors, fullerenes, dyes, metals, crystals, and liquids (bulk samples, suspensions, solutions, embedded nanoparticles, and thin films) is presented. Some of these media are analysed as optical limiters of intense laser radiation. We present our measurements of their nonlinear refractive indices, nonlinear absorption coefficients, saturation intensities, and nonlinear susceptibilities using the laser pulses generated in various spectral and temporal ranges. Various techniques for the preparation of nanoparticles in different solvents are discussed. We also present our studies of the high-order nonlinearities of some of these media.
TL;DR: In this article, a modified conformal-mask optical lithography arrangement has been used for near-field imaging through planar silver lenses, achieving feature resolution of up to 250 nm using broadband illumination from a mercury lamp.
Abstract: Near-field imaging through planar silver lenses has been demonstrated using a modified conformal-mask optical lithography arrangement. Dense feature resolution down to 250 nm (on a 500 nm period) has been achieved in 50 nm thick photoresist on silicon using broadband illumination from a mercury lamp. Finite difference time domain simulations have been performed to show the resolution improvements that can be expected for imaging through such silver lenses compared with near-field proximity imaging. The resolution enhancements that are predicted are in good agreement with the experimental results, and the conditions by which sub-diffraction-limited resolution may be achieved are given.
TL;DR: In this article, the authors outline a new concept for active plasmonics that exploits light-induced nanoscale structural transformations in the waveguide material, illustrated by numerical modelling and test experiments on a gallium-dielectric interface.
Abstract: We outline a new concept for active plasmonics that exploits light-induced nanoscale structural transformations in the waveguide material. The concept is illustrated by numerical modelling and test experiments on a gallium–dielectric interface. We also discuss other possible implementations of the concept such as an electro-plasmon modulator, a plasmon detector and a switch that controls one plasmon wave with another.
TL;DR: In this article, the effect of spherical aberration on the propagation of a single tightly focused femtosecond laser pulse inside fused silica was studied and it was shown that spherical aberrations induced by the air-sample interface extended the focal region and played an important role in the formation of the long plasma channel.
Abstract: We show the effect of a spherical aberration on the propagation of a single tightly focused femtosecond laser pulse inside fused silica. At high power, a long plasma channel across the geometrical focus can be observed under deep focusing. The total channel length decreases with the decrease of the focusing depth at fixed focal length. We found that the spherical aberration induced by the air–sample interface extends the focal region and plays an important role in the formation of the long plasma channel. In certain conditions this spherical aberration can be compensated by a spherical aberration induced by the objective used to focus the laser.
TL;DR: In this paper, a collection of experiments used to characterize both the linear and second-order optical responses of the arrays of low-symmetry L-shaped gold nanoparticles is discussed.
Abstract: We summarize our work on polarization effects in arrays of low-symmetry L-shaped gold nanoparticles. A collection of experiments used to characterize both the linear and second-order optical responses of the arrays is discussed. The responses of the arrays are found to be exceptionally sensitive to polarization. This sensitivity is determined to arise from structural properties including particle size, shape, spacing, and orientation. Nonlinear polarization measurements are shown to yield unexpected and very interesting information concerning the symmetry of the nanoparticle arrays. The combined linear and nonlinear results confirm that the smallest details of arrays influence optical responses.
TL;DR: In this paper, the cross-polarization effects in the SRR and the CSRR are considered, and it is shown that they permit resonance to occur for normally incident plane wave excitation.
Abstract: Frequency selective surfaces (FSSs) made up of periodic arrays of split ring resonators (SRRs) are analysed. This analysis includes complementary screens, or complementary SRR-FSSs (CSRR-FSSs). It is shown that these FSSs show a dual behaviour, with a stop/pass band behaviour at the frequency of resonance of the SRRs/CSRRs. Cross-polarization effects in the SRR and the CSRR are considered, and it is shown that they permit resonance to occur for normally incident plane wave excitation. This latter property of SRRs and CSRRs also implies that the FSSs considered may act as polarizers and polarization converters as well. An analytical theory, valid for perfectly conducting and infinitely thin screens, is proposed for the SRR-FSSs and CSRR-FSSs. These approximations are valid in the microwave and millimetre-wave range, and up to the terahertz range.
TL;DR: In this paper, a self-mixing interferometry method has been developed for the determination of sub-micron particle sizes and for the measurement of flows in narrow diameter tubes.
Abstract: New applications are presented for self-mixing interferometry, based on optical scattering, feedback and self-mixing in laser diodes. The self-mixing interferometry method has been developed for the determination of sub-micron particle sizes and for the measurement of flows in narrow diameter tubes. The rate equations for laser diodes subjected to frequency-shifted feedback are reviewed and extended to include a normalized frequency distribution to be characterized by the backscattered light spectrum. Experimental investigations are presented for (a) particle sizing using polystyrene particles in water from 0.02 to 0.20 mu m in diameter and (b) for transverse velocity profile determination using a 1.4 mm diameter tube with flow rates ranging between 10 and 100 ml h(-1). The observed frequency band increases for smaller particles when observing Brownian motion and for higher flow rates when observing flowing liquids. This experimental technique is inherently simple and low cost. Further potential applications of this technique include blood flow measurement in medicine, electrophoresis investigations in biology and particle characterization in process engineering and chemistry.
TL;DR: In this article, a review of recent work and work under way in our laboratory tending towards synthesis based on self-assembly to realize metamaterials in the optical range is presented.
Abstract: Photonic crystals can be viewed just as a subclass of a larger family of material systems called metamaterials in which the properties largely derive from the structure rather than from the material itself. Opals have only a relatively recent history as photonic bandgap materials and have received a strong thrust from their adequacy as scaffoldings for further templating other materials with photonic applications for instance. The tortuous route from materials to devices might perhaps find reward in the ease and low cost of fabrication of these materials. In this paper we present a review of recent work and work under way in our laboratory tending towards synthesis based on self-assembly to realize metamaterials in the optical range. This comprises the formation of the templates (opals) and subsequent synthesis of guest materials such as semiconductors, metals and insulators. The possibility of further processing allows additional two-dimensional and quasi-two-dimensional patterning for the design of new structures. In this paper we show how the raw matter can be checked for quality and learn how to use its optical properties to evaluate application potential. Issues relating to the optical properties (such as crystalline quality, finite size effects and infiltration with other materials) are examined. We show some examples where opals are used to pattern the growth of other materials with photonic applications (such as metals and semiconductors) and developments leading to both vertical and lateral engineering are shown.
TL;DR: This work proposes several methods for anaglyph enhancement that rely on stereo image registration, defocusing and nonlinear operations on synthesized depth maps to substantially reduce unwanted ghosting artefacts, improve the visual quality of the images, and make comfortable viewing of the same sequence possible in three-dimensional as well as the two-dimensional mode of thesame sequence.
Abstract: Anaglyphs are one of the most economical methods for three-dimensional visualization. This method, however, suffers from severe drawbacks such as loss of colour and extreme discomfort for prolonged viewing. We propose several methods for anaglyph enhancement that rely on stereo image registration, defocusing and nonlinear operations on synthesized depth maps. These enhancements substantially reduce unwanted ghosting artefacts, improve the visual quality of the images, and make comfortable viewing of the same sequence possible in three-dimensional as well as the two-dimensional mode of the same sequence.
TL;DR: In this paper, a multilayer metallodielectric thin-film bandpass filter for the ultraviolet range was designed and produced by applying the concept of transparent metals.
Abstract: We designed and produced silver–silicon dioxide multilayer thin-film bandpass filters for the ultraviolet range by applying the concept of ‘transparent metals’. To calculate the transmission of the designed metallodielectri cfi lters we used the transfer matrix method for lossy structures. We fabricated our multilayer metallodielectric films using radiofrequent sputtering and characterized them by spectral transmission measurements. We achieved satisfactory suppression of undesired visible and infrared parts of the spectrum even for a small number of layer pairs.
TL;DR: In this paper, the optical transport properties of complex photonic structures ranging from ordered photonic crystals to disordered strongly-scattering materials, with particular focus on the intermediate regime between complete order and disorder, are discussed.
Abstract: We discuss the optical transport properties of complex photonic structures ranging from ordered photonic crystals to disordered strongly-scattering materials, with particular focus on the intermediate regime between complete order and disorder. We start by giving an overview of the field and explain the important analogies between the transport of optical waves in complex photonic materials and the transport of electrons in solids. We then discuss amplifying disordered materials that exhibit random laser action and show how liquid crystal infiltration can be used to control the scattering strength of random structures. Also we discuss the occurrence of narrow emission modes in random lasers. Liquid crystals are discussed as an example of a partially ordered system and particular attention is dedicated to quasi-crystalline materials. One-dimensional quasi-crystals can be realized by controlled etching of multi-layer structures in silicon. Transmission spectra of Fibonacci type quasi-crystals are reported and the (self-similar) light distributions of the transmission modes at the Fibonacci band edge are calculated and discussed.
TL;DR: In this article, it was shown that R6G laser dye in a concentration of 0.1 g l−1 mixed with a solution of aggregated silver nanoparticles exhibits a new emission band with a maximum at 612 nm.
Abstract: We have found that R6G laser dye in a concentration of 0.1 g l−1 mixed with a solution of aggregated silver nanoparticles exhibits a new emission band with a maximum at 612 nm. This band does not exist in pure dye of comparable concentration or in a mixture of dye with a solution of single silver nanoparticles. A qualitatively similar red-shifted emission band is observed in pure R6G dye at very high concentration (3.8 or 16.7 g l−1). In both cases, no changes occur to the shapes of the absorption spectra of the dye. We explain the observed spectral changes in terms of J-aggregates of R6G molecules whose formation is probable in the presence of Ag aggregates with a complicated surface structure and is much less likely in the case of adsorption of dye molecules on single Ag nanoparticles. Alternatively, many features observed in the experiment can be explained by an enhancement of the rates of spontaneous radiative transitions in the proximity of metallic particles, which is due to a modification of the local density of electromagnetic modes in the vicinity of metal surfaces at energies resonant with surface plasmon resonances.
TL;DR: In this article, an acrylamide-based photopolymer formulated in the Centre for Industrial and Engineering Optics has been investigated with a view to further optimization for holographic data storage.
Abstract: An acrylamide-based photopolymer formulated in the Centre for Industrial and Engineering Optics has been investigated with a view to further optimization for holographic data storage. Series of 18–30 gratings were angularly multiplexed in a volume of photopolymer layer at a spatial frequency of 1500 lines mm−1. Since the photopolymer is a saturable material, an exposure scheduling method was used to exploit the entire dynamic range of the material and allow equal strength holographic gratings to be recorded. This investigation yielded the photopolymer M/# for moderately thin layers. Photopolymer temporal stability was also studied by measuring variations of material shrinkage, Bragg selectivity curve, and diffraction efficiency.
TL;DR: In this paper, the authors investigated the properties of sub-wavelength plasmonic crystals (SPCs), a class of two-dimensional periodic nanostructured materials with negative dielectric permittivity, with the lattice period much smaller than the wavelength of light.
Abstract: Electromagnetic properties of a new class of two-dimensional periodic nanostructured materials, sub-wavelength plasmonic crystals (SPCs), are investigated. An SPC is a periodic lattice of metallic inclusions with negative dielectric permittivity � 0, with the lattice period much smaller than the wavelength of light. It is found that two types of propagating electromagnetic waves are supported by SPCs: (a) scale-invariant modes whose dispersion relation is almost independent of the lattice period, and (b) scale-dependent narrow-band resonances whose dispersion strongly depends on the lattice period. The scale-invariant modes are accurately described using a frequency-dependent
TL;DR: In this article, a non-invasive multi-spectral method based on the radiation of monochromatic light, emitted by laser diodes in the range 600-1400 nm, through an area of skin on the finger is described.
Abstract: The development of the photometric device described here is based on the realization of a photoplethysmography measurement device developed for the German Space Agency DLR. It is well known in biomedical engineering that pulsatile changes of blood volume in tissue can be observed by measuring the transmission or the reflection of light (Roberts 1982 Trans. Inst. Meas. Control 4 101–6). The non-invasive multi-spectral method described here is based on the radiation of monochromatic light, emitted by laser diodes in the range 600–1400 nm, through an area of skin on the finger. After interaction with the tissue the transmitted light is detected non-invasively by photo-diodes. The method makes use of the intensity fluctuations caused by the pulse wave. The ratio between the peak to peak pulse amplitudes measured at different wavelengths and its dependence on the optical absorbability characteristics of human blood yields information on the blood composition. Deferrals between the proportions of haemoglobin and water in the intravasal volume should be detected photo-electrically by signal-analytic evaluation of the signals. The computed coefficients are used for the measurement and calculation of the arterial oxygenic saturation (SaO2) and the relative haemoglobin concentration change. Results of clinical measurements are presented for a deoxygenation study with ICG-bolus injection (indocyanine green).
TL;DR: In this article, a novel virtual phase calibrating model plane method for coordinate calibration in fringe projection profilometry is presented, which is more efficient in that it needs only to grab and process one series of images of the model plane.
Abstract: A novel virtual phase calibrating model plane method for coordinate calibration in fringe projection profilometry is presented in this paper. Plane (X-axis and Y-axis) calibration and height (Z-axis) calibration are studied respectively. The virtual phase calibrating model plane method is designed to calibrate the coordinates. Experimental results show that the proposed calibration procedure using the virtual phase calibrating model plane method is more efficient in that it needs only to grab and process one series of images of the model plane, whereas the traditional calibration method requires at least two series of images.
TL;DR: In this paper, a biologically inspired approach is proposed in which a compact hyperspectral fovea is embedded within a conventional panchromatic periphery, which can be used to identify objects in a scene.
Abstract: We address the two dominant dilemmas encountered in attempting to demonstrate real-time hyperspectral imaging: how to record a three-dimensional spectral data cube with a conventional two-dimensional detector array and how to most efficiently transmit the spectral data cube through the information bottleneck constituted by the detector’s limited space–bandwidth product. We have demonstrated a new, biologically inspired approach in which a compact hyperspectral fovea is embedded within a conventional panchromatic periphery. Combined with an intelligent scanning system this will enable hyperspectral imaging to be applied only to small regions of interest previously identified using the panchromatic periphery, thus improving the efficiency with which hyperspectral imaging can be used to recognize objects in a scene. The hyperspectral fovea is realized using a coherent optical fibre bundle that reformats a two-dimensional input image into a linear output image that acts as the input to a one-dimensional, dispersive hyperspectral imager.
TL;DR: In this paper, the authors consider the propagation of electromagnetic waves in a circular fiber with a core of negative-refractive-index metamaterials and show the peculiar mode properties of a fiber with simultaneously negative dielectric permittivity and magnetic permeability of the core.
Abstract: We consider propagation of electromagnetic waves in a circular fibre with a core of negative-refractive-index metamaterial. We study the fast and slow guided modes of a dispersive fibre and the mode properties depending on the fibre parameters. We show the peculiar mode properties of a fibre with simultaneously negative dielectric permittivity and magnetic permeability of the core: the perfect phase matching of the TE and TM slow modes, sign-varying energy flux, and the existence of TEM modes.