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This study was conducted to analyze the influence of binocular vision and accommodation anomalies on refraction dynamics. Our results may help to design more accurate autorefractors and to better understand the difficulties in prescribing an optical correction or adaptation to a correction.This study aimed to verify whether viewing conditions (open- or closed-field) or vision anomalies, such as ocular surface diseases, accommodative dysfunctions, and binocular vision anomalies, influence (1) the differences between subjective refraction and autorefraction and (2) the characteristics of the short-term refractive state variation.The subjective refraction of 64 subjects aged 23 to 60 years was measured during a comprehensive optometric examination, and the Ocular Surface Disease Index questionnaire was collected. Twenty successive measurements of automated refraction of each eye were obtained using a conventional autorefractor Nidek ARK-510A and an open-field autorefractor Shin-Nippon NVision-K 5001. Conventional notation of refractive error (sphere, cylinder, axis) was transformed to h-vectors, presented in scatterplots, and analyzed statistically.The three-way analysis of variance tests showed that there is no influence of accommodation dysfunctions (P = .22 for ARK-510A), binocular vision anomalies (P = .97 for ARK-510A), and ocular surface diseases (P = .20 for ARK-510A) on differences between autorefraction and subjective refraction. The binocular vision anomalies affected the results from open-field autorefractor, whereas the accommodation impacted closed-field refraction measurements. Changes in short-term refractive state variation occurred in sphere power, indicating accommodative state changes; however, 30 subjects demonstrated at least one outlier and/or polymodality of refractive state distributions.The study showed that the presence of accommodative dysfunctions or binocular vision anomalies might increase the range of short-term refractive state variation. The impact of vision anomalies differs between viewing conditions. The polymodal distribution of refractive state variation and the presence of outliers imply that automatic modes used typically in autorefractors with three to five readings may not accurately represent the refractive state of the eye.

Miękkie soczewki kontaktowe służące do korekcji ametropii są powszechnie używane na całym świecie. Jako wyrób medyczny powinny być dopasowywane i systematycznie oceniane na oku pacjenta przez specjalistów ochrony wzroku. Badanie kontrolne powinno obejmować ocenę osadów na soczewkach. Powszechne stosowanie soczewek silikonowo-hydrożelowych (Si-Hy) i ich tendencja do odkładania się złogów lipidowych wskazują, że specjaliści ochrony wzroku powinni zwracać szczególną uwagę na ten rodzaj osadów. Celem niniejszej pracy jest analiza opinii polskich specjalistów ochrony wzroku w zakresie osadów na soczewkach kontaktowych, ze szczególnym uwzględnieniem lipidów i soczewek Si-Hy. Dane zebrano od 103 polskich specjalistów ochrony wzroku poprzez ankietę internetową. Respondenci wskazali, że osady lipidowe najczęściej występują na soczewkach Si-Hy, a osady białkowe na soczewkach hydrożelowych. Niemal wszyscy ankietowani deklarują, że oceniają osady na soczewkach kontaktowych podczas wizyt kontrolnych, co pozwala wnioskować, iż jest to dla nich istotna część procesu doboru soczewek. Respondenci uważają, że poszczególne soczewki i płyny do ich pielęgnacji różnią się w kontekście ich interakcji z osadami lipidowymi. Parametry te powinny być brane pod uwagę w momencie wyboru produktu dla pacjenta. Specjaliści ochrony wzroku oczekują opisów odporności soczewek na powstawanie osadów lipidowych oraz skuteczności płynów pielęgnacyjnych w redukcji osadów lipidowych.

All-normal dispersion supercontinuum (ANDi SC) generation in a lead-bismuth-gallate glass solid-core photonic crystal fiber (PCF) with cladding air-holes infiltrated with carbon tetrachloride (CCl4) is experimentally investigated and numerically verified. The liquid infiltration results in additional degrees of freedom that are complimentary to conventional dispersion engineering techniques and that allow the design of soft-glass ANDi fibers with an exceptionally flat near-zero dispersion profile. The unique combination of high nonlinearity and low normal dispersion enables the generation of a coherent, low-noise SC covering 0.93–2.5 µm requiring only 12.5 kW of pump peak power delivered by a standard ultrafast erbium-fiber laser with 100 MHz pulse repetition rate (PRR). This is a much lower peak power level than has been previously required for the generation of ANDi SC with bandwidths exceeding one octave in silica- or soft-glass fibers. Our results show that liquid-composite fibers are a promising pathway for scaling the PRR of ANDi SC sources by making the concept accessible to pump lasers with hundreds of megahertz of gigahertz PRR that have limited peak power per pulse but are often required in applications such as high-speed nonlinear imaging, optical communications, or frequency metrology. Furthermore, due to the overlap of the SC with the major gain bands of many rare-earth fiber amplifiers, our source could serve as a coherent seed for low-noise ultrafast lasers operating in the short-wave infrared spectral region.

Silicone hydrogel (Si-Hy) contact lenses are a common form of correction of refractive errors and are prescribed by eye care professionals around the world. Si-Hy lenses perform in a complex environment, which is the surface of the eye and the tear film. Therefore, they are exposed to various factors, such as lipid deposits. The aims of this paper are to review available scientific reports on the study of Si-Hy lens interactions with lipids and search for further research objectives. A total of 57 publications were identified and reviewed, from 2003 to 2020. In general, Si-Hy lenses are more likely to accumulate lipid deposits than traditional hydrogel lenses, although there are significant differences between Si-Hy lens materials that may result from different methods used in the studies. The review includes studies on various aspects of interactions between lenses and lipids, such as those concerning the effectiveness of lipids removal from lenses by care solutions. The conclusion points out future research directions, such as measurements of lipid diffusion in Si-Hy lens' matrices.

In this work we present a numerical study on attenuation of the fundamental mode in a suspended-core photonic crystal fibre (SC-PCF) made of fused silica, when a biological layer with various thickness and complex refractive index is present on the struts supporting the core and the photonic cladding (channels) is filled with water. In such a fibre structure both the effective refractive index and the mode area increase nonlinearly with the refractive index and with the thickness of the bio-layer, that in turn causes the increase of the attenuation of the fundamental (highest- n e f f ) mode. For the calculation wavelength of 1 μ m the increase is intensified when the refractive index of the bio-layer exceeds 1.42, what is usually the case when even thin bio-layer is concerned. It is shown that it is possible to use such a fibre as a label-free sensor of a certain bio-layer deposited on a functionalised inner surface of the fibre.

In this paper, the accuracy of noncycloplegic refractive error measurements performed by three autorefractors, Nidek ARK-510A, Visionix L80 Wave+, and Shin-Nippon NVision-K 5001, compared with subjective refraction (SR) in young adults is analyzed using statistical methods. The analysis is carried out in terms of spherical equivalent (SE), astigmatism, and two Jackson crossed-cylinder vectors. Fifty-one subjects aged 19-23 were examined. The differences between objective refraction (OR) measured by autorefractors are not statistically significant in either SE or cylindrical components. However, in comparison with subjective refraction, the best agreement in SE was provided by K 5001. For all instruments, differences in SE between OR and SR are statistically significant.

In this paper we present a large mode area photonic crystal fiber made of the heavy metal oxide glass CS-740, dedicated for a broadband light guidance in the visible, near- and mid-infrared regions of wavelengths from 0.4 to 4.7 μm. The fiber is effectively multi-mode in the considered wavelength range. It is composed of a ring of air-holes surrounding the core, with a high linear filling factor of 0.97. The fiber was made using a standard stack-and-draw technique. Each hole has a size of approx. 2.5 × 3.0 μm and diameter of core is 80 μm. Fiber attenuation is below 3 dB/m in the 0.9–1.7 μm wavelength range, while at 4.4 μm (mid-IR) it is approx. 5 dB/cm. Bending loss at the 1.55 μm wavelength is 0.45 dB per loop of 8 mm radius. Fiber numerical aperture is 0.53 at 1.55 μm. The effective mode area of the fundamental mode is approx. 2400 μm 2 in the wavelength range of 0.8–1.7 μm. We present a proof-of-concept demonstration that our large core photonic crystal fiber is able to efficiently collect light directly from a mid-IR quantum cascade laser without use of additional optics and can be used for pigtailing mid-IR sources and detectors.

Octave spanning all-normal dispersion supercontinuum generation (SCG) was experimentally demonstrated in a solid, suspended-core fiber (SCF) infiltrated with water. Replacement of air with water in the cladding air-holes leads to a dramatic modification of the dispersion profile of the fiber, significantly flattening the characteristic over the visible and much of the near-infrared wavelength range at normal values. In such a fiber infiltrated with water, all-normal dispersion supercontinuum was generated with the spectral coverage from 435 nm to 1330 nm using femtosecond pumping with the output peak power of 150 kW and 800 nm central wavelength. The SCF without water infiltration – air in the cladding region – had a zero-dispersion wavelength at 760 nm and enabled the generation of the anomalous dispersion dynamics-based SCG in the wavelength range from 450 nm to 1250 nm. We also numerically calculated the coherence of simulated supercontinuum pulses with one-photon-per-mode noise seeds and point out that the all-normal dispersion SCG in suspended-core fiber infiltrated with water has the potential for high temporal coherence, while the fiber without water infiltration shows gradual decoherence of generated supercontinuum pulses with increasing pump power, over similar peak power range.

In the paper the results of AFM surface profile measurements of seven new long-wear contact lenses (CL) available in Poland are presented. Calculated statistical roughness parameters are shown, namely standard deviation (RMS), mean roughness, maximum difference between peak and valley, skewness, and kurtosis. It is demonstrated that CLs manufactured using recent methods, such as two-stage polimerisation or extending silicon chains exhibit small RMS, less than 10 nm, in comparison with older generation CLs which maintains RMS on the level of tens of nanometers. Then, a comparison of results obtained using a typical silicon tip and a silicon tip covered with alkylsilane is also demonstrated. As a result, roughness parameters, such as RMS, are higher for the case of alkylsilane-coated tip than for a typical silicon tip, 8.39 ± 0.16 nm vs. 6.22 ± 0.9 nm, which leads to the conclusion that the proper choice of the tip material significantly influences the outcome of the experiment. Finally, the reliability and limits of such measurements are discussed.

We report on our latest research in the field of nanostructured optical components fabricated using stack and draw technique. The concept of nanostructuring is based on the idea that the macroscopic optical properties of the system can be controlled by introduction of subwavelength elements. In some geometries even a single nanoinclusion can significantly change the performance of the device, in others incorporation of large amount of subwavelength elements justifies the usage of effective medium theory. Here, we demonstrate that nanostructurization through stack-and-draw method leads to development of fibres with carefully design birefringence and allows fabrication of elements of arbitrary effective index profiles. On the basis of Energy-dispersive X-ray spectroscopy measurements we also discuss the impact of selective diffusion process on optical properties of considered systems and show that this mechanism can be treated either as an opportunity to extend the dispersion engineering flexibility in optical elements or as a limitation which introduces the uncertainty of the final dispersion profile of the nanostructured components.

Introduction of subwavelength inclusions in the core opens up an additional degree of freedom in shaping of dispersion characteristic in photonic crystal fibers (PCFs). We have developed a PCF with a nanostructured inclusion in the core to verify this concept. To suppress higher order modes, the photonic cladding structure of the developed fiber is composed of a first ring with linear filling factor of 0.95 and the remaining 5 rings with a lower linear filling factor of 0.4 with a lattice constant of \(2.6\,\upmu \hbox {m}\). Diameter of the nano-inclusion in the core is 410 nm. For the fiber development, we used a pair of thermally matched soft glasses: Schott SF6 lead glass and an in-house synthesized NC21 borosilicate glass. In this paper, we report on dispersion measurements using a spectral interferomeric technique. A dispersion unbalanced Mach–Zehnder interferometer, combined with a supercontinuum source is used. Dispersion characteristics in wide range of wavelengths extending from 0.65 to \(1.6\,\upmu \hbox {m}\), are measured and verified against calculated results.

Supercontinuum from 800 to 2,600 nm has been obtained in a soft glass suspended-core photonic crystal fiber. The fiber has been fabricated using an in-house synthesized, lead-bismuth-galate oxide glass (PBG-08), which has a transmission window from 500 nm to 4,500 nm. Dispersion characteristic has been designed to enable efficient pumping in the anomalous regime, using typical telecommunication wavelengths and influence of discrepancy between design and physical dispersion profile of fiber is discussed. An optical parametric amplifier system seeded with a Ti:Sapphire oscillator has been used as a light source (70 fs pulses with 100 kHz repetition rate). Supercontinuum bandwidth on the mid-infrared side is limited by OH $$^-$$ absorption of the glass and presence of second zero-dispersion wavelength in the spectral area of interest. Flatness the spectrum remains under 7 dB from roughly 1,800 nm to about 2,500 nm.

We present a numerical study of the dispersion characteristic modification in a nonlinear photonic crystal fibre (PCF) infiltrated with organic solvents. The PCF is made of PBG08 glass and was developed in the stack-and-draw process. The PBG08 glass has a high refractive index (n < 2.0), high nonlinear refractive index (n2 = 4.3×10−19 m2/W) and good rheological properties that allow for thermal processing of the glass without crystallization. In the numerical study 18 different solvents were used. The dispersion, mode area, and losses characteristics were calculated. The zero dispersion wavelength (ZDW) of the fibre can be shifted towards longer wavelengths by approx. 150 nm by using Nitrobenzene as infiltrating liquid and by a smaller value using other liquids. At the same time the mode area of the fundamental mode increases by approx. 5 to 15% depending on the wavelength considered. The confinement losses increase significantly for six analysed liquids by a few orders of magnitude up to 102 dB/m. Our approach allows to combine high nonlinearities of the soft glass with the possibility to tune zero dispersion wavelength to the desired value.

A photonic crystal fiber (PCF) made of fused silica glass, infiltrated with carbon tetrachloride (CCl4), is proposed as a new source of supercontinuum (SC) light. Guiding properties in terms of effective refractive index, attenuation, and dispersion of the fundamental mode are studied numerically. As a result, two optimized structures are selected and verified against SC generation in detail. The dispersion characteristic of the first structure has the zero-dispersion wavelength at 1.252 μm, while the dispersion characteristic of the second structure is all-normal and equals -4.37 ps·nm-1·km-1 at 1.55 μm. SC generation was demonstrated for the wavelengths 1.064 μm, 1.35 μm, and 1.55 μm. We prove the possibility of coherent, octave-spanning SC generation with 300 fs pulses with only 0.8 nJ of energy in-coupled into the core with each of the studied structures. Proposed fibers are fully compatible with all-silica fiber systems and PCFs with wide mode area, and can also be used for all-fiber SC sources. The proposed solution may lead to new low-cost all-fiber optical systems.

An algorithm and a computer routines library written in object programming language C++ are described, which allow removal of global intensity deformation in a grey-scale image using contrast control. During the process, a Gaussian pyramid representation of an input image is constructed through low-pass filtration and sampling of successive pyramid levels, where the input image constitutes the first (zero) level of the pyramid. In the second step a Laplacian pyramid is built by subtracting successive levels of the Gaussian pyramid. Then, all levels in the Laplacian pyramid are expanded to the original image size and added with weights, which are real numbers, to reconstruct the image. Proper choice of the weights allows global grey-level deformation removal. This technique can be applied for contrast enhancement and image archiving of airborne, scanned, photo-copied and optical camera-made images, where global distortions of intensity are frequently met.

To achieve high non-linearity in photonic crystal fibers a high nonlinear coefficient of the glass is required accompanied by high coupling efficiency and flat dispersion profile of the fiber with the specific zero dispersion wavelength. In this paper, we present a deterministic method that allow step-by-step design of photonic crystal fibers with desired zero dispersion wavelength, modality and coupling efficiency due to sequential engineering of geometrical parameters of microstructured fibers with nanostructured cores. The fiber consists of inclusions of low refractive index material, embedded in a host glass of higher refractive index, where a single central micro-rod is omitted. In its place an additional nano-inclusion is located of a given diameter. The choice of the glass determines the nonlinear coefficient of the fiber and fabrication possibilities as well. Zero dispersion wavelength is varied by the change of the lattice constant of the cladding. High filling factor in the cladding leads to a large number of propagating high order modes, which can be selectively cut off, when the filling factor of the outer part of the cladding is reduced. The diameter of the nano-inclusion in the core is responsible for the fundamental mode area, which influences directly the coupling efficiency. Several designed structures were modeled numerically and developed to confirm the design method.

We present a numerical study of the dispersion characteristic modification of nonlinear photonic crystal fibers infiltrated with liquids. A photonic crystal fiber based on the soft glass PBG-08, infiltrated with 17 different organic solvents, is proposed. The glass has a light transmission window in the visible-mid-IR range of 0.4-5 μm and has a higher refractive index than fused silica, which provides high contrast between the fiber structure and the liquids. A fiber with air holes is designed and then developed in the stack-and-draw process. Analyzing SEM images of the real fiber, we calculate numerically the refractive index, effective mode area, and dispersion of the fundamental mode for the case when the air holes are filled with liquids. The influence of the liquids on the fiber properties is discussed. Numerical simulations of supercontinuum generation for the fiber with air holes only and infiltrated with toluene are presented.

We present a novel method for the development of diffractive optical elements (DOEs). Unlike standard surface relief DOEs, the phase shift is introduced through a refractive index variation achieved by using different types of glass. For the fabrication of DOEs we use a modified stack-and-draw technique, originally developed for the fabrication of photonic crystal fibers, resulting in a completely flat element that is easy to integrate with other optical components. A proof-of-concept demonstration of the method is presented-a two-dimensional binary optical phase grating in the form of a square chessboard with a pixel size of 5 μm. Two types of glass are used: low refractive index silicate glass NC21 and high refractive index lead-silicate glass F2. The measured diffraction characteristics of the fabricated component are presented and it is shown numerically and experimentally that such a DOE can be used as a fiber interconnector that couples light from a small-core fiber into the several cores of a multicore fiber.

In this paper we report a two octave spanning supercontinuum generation in the range 750-3000 nm with a newly developed photonic crystal fiber. The fibre is fabricated using an in-house synthesized lead-bismuth-galate glass PBG08 with optimised rheological and transmission properties in the range 500-4800 nm. The photonic cladding consists of 8 rings of air holes with a fibre core diameter of 3 μm and a lattice constant of 2.2 μm. The dispersion characteristic is determined mainly by the material dispersion and the first ring of holes in the cladding with a filling factor of 0.68. The filling factor of the remaining 7 rings is 0.45 which allows single mode performance of the fibre in the infrared range. The fibre has a zero dispersion wavelength of 1490 nm which allows the use of 1550 nm wavelength as an efficient pump in the anomalous dispersion regime. The 2 cm long sample of photonic crystal fiber is pumped in the femtosecond regime with a pulse energy of 10 nJ at a wavelength of 1550 nm. A flatness of 5 dB is observed in the spectral range 950-2500 nm.

We present the development of a large core multimode photonic crystal fibre with hyperspectral transmission that covers the visible, near and (in part) mid infra-red wavelength ranges (400-6500 nm). We have optimised the composition of a heavy metal-oxide glass based on the PbO-Bi2O3-Ga2O3 system modified with Nb2O5, Ta2O5, SiO2, GeO2, BaO, CdO, Na2O and K2O. The optimised glass shows good transmission up to 6 μm as well as good rheological properties that permits multiple thermal processing steps in an optical drawing tower without crystallisation. The selected glass is synthesized inhouse and has been used for fibre development. We have fabricated a multi-mode photonic crystal fibre with an effective mode area of 295 μm2. The photonic cladding is composed of 8 rings of air holes with a fill factor of 0.46. The transmission of a hyperspectral spectrum is experimentally verified using a broadband source. The attenuation of the fibre and its sensitivity to bending losses is presented.

The development of all-solid photonic crystal fibers for nonlinear optics is an alternative approach to the air-glass solid core photonic crystal fibers. The use of soft glasses ensures a high refractive index contrast (>0.1) and a high nonlinear coefficient of the fibers. In addition, the manipulation of the subwavelength structure of the core of a photonic crystal fiber allows significant modification of its dispersion characteristics and efficient generation of supercontinuum with various femtosecond and nanosecond sources. The development of all-solid photonic crystal fiber allows very accurate control of all the parameters of the developed fiber in very good agreement with the design criteria. In this paper, we report on the dispersion management capabilities in all-solid photonic crystal fibers with nanostructured cores using thermally matched glasses, which can be jointly processed using the stack-and-draw fiber fabrication technology. We consider a photonic crystal fiber made of the high index lead-silicate glass SF6 and the in-house synthesized low index silicate glass NC21. The NC21 glass plays the role of low index inclusion in the photonic cladding and a nano-inclusion in the core of the fiber. The final dispersion profile of the photonic crystal fiber is determined by the low index nano-inclusion in the core with diameter in the range 100-500nm. The dispersion profiles are modeled for a theoretical structure and for the developed fiber. Supercontinuum generation is expected and numerically confirmed for the developed fiber in the range 1150-1500nm with flatness below 1dB. The fiber is dedicated for supercontinuum generation with 1550nm laser sources.

The development of all-solid photonic crystal fibres for nonlinear optics is an alternative approach to air-glass solid core photonic crystal fibres. The use of soft glasses ensures a high refractive index contrast (> 0.1) and a high nonlinear coefficient of the fibres. We report on the dispersion management capabilities in all-solid photonic crystal fibres taking into account four thermally matched glasses which can be jointly processed using the stack-and-draw fibre technique. We present structures with over 450 nm broadband flat normal dispersion and ultra-flat near zero anomalous dispersion below 5 ps/nm/km over 300 nm dedicated to supercontinuum generation with 1540 nm laser sources. The development of an all-solid photonic crystal fibre made of F2 and NC21 glasses is presented. The fibre is used to demonstrate supercontinuum generation in the range of 730–870 nm (150 nm) with flatness below 5 dB.

In this paper we study the propagation of light through silver-dielectric metamaterial layered prism which operates in the canalization regime. The prism is illuminated with TM-polarized light and is designed using the effective medium theory as strongly anisotropic and impedance matched to air. The structure has an infinite value of the effective permittivity in the direction perpendicular to layer surfaces. Therefore it is able to couple a broad spectrum of incident spatial frequencies, including evanescent waves, into propagating modes. As a result, subwavelength resolution at the output interface of the structure is observed. Further the device is characterised with the transfer matrix method (TMM), and investigated with Finite Difference Time Domain method (FDTD). Two parameters of the prism are studied, namely the angle of incidence and the apex angle, to obtain the best resolution.

In the paper metamaterial nanotips with multi-frequency local field enhancement are proposed and studied theoretically and numerically. The nanotips are in form of pyramids built from silver nanoplates embedded in a dielectric block. The pyramids are layered structures with subsequent plates parallel to the pyramid base. Thickness of nanoplates and their transversal size is chosen to efficiently convert the light impinging on the pyramid base into hot spots near the pyramid apex, and also to support large number of plasmonic resonances which allow for multi-frequency enhancement of the light intensity. Geometrical parameters are designed to cover the visible light range.

We investigate the optical properties of a three-dimensional metamaterial nanotip that has a pyramidal shape. The nanotip itself is made of a large number of densely packed metallic nanospheres. In analogy to the emergence of a continuous energy band in a crystal, the strong coupling among neighboring nanospheres forces them to act collectively and allows the observation of a broad plasmonic band. The largely increased degrees of freedom within the metamaterial nanotip allow to sustain a great variety of different localized eigenmodes. In this contribution, we systematically reveal their peculiar polarization state and show that they allow for light localization in various well-defined spatial domains.

Optical metamaterials with a negative value of the refractive index can be fabricated by means of patterning techniques developed for microelectronics. One of those is a layered metamaterial, where the electric and magnetic response comes from coupled parallel subwavelength size wires. We simulate propagation of EM waves through such a metamaterial. Its properties depend on the density of pairs of nanowires oriented in parallel in one layer. There is a tradeoff between high transmittance and large negative refractive index value n. The smaller is the density of nanowires; 1 masculine - the narrower the range of frequencies, where n is negative; 2 masculine - the less negative is n; 3 masculine - the higher is the transmission.

In this communication we present technical details of performance of recently proposed silver nanolens which transforms a far-field source into a far-field focus [P. Wrobel, J. Pniewski, T.J. Antosiewicz, T. Szoplik, “Focusing radially polarized light by concentrically corrugated silver film without a hole” Phys. Rev. Lett., in print (2009)]. The nanolens is a free standing silver nanolayer with no hole on the optical axis and double-sided concentric corrugations. The nanolens, when illuminated with a radially polarized Laguerre-Gauss beam, focuses light in the far-field at distances equal 1 – 3 wavelengths depending upon wavelength and its geometry. Foci of diameter equal nearly 0.4 of a wavelength are achievable. The nanolens acts like a classical optical high-numerical aperture system. Simulations using body-of-revolution finite-difference time-domain method illustrate the idea.

In this paper we present technical details of a metal nanolens in the form of a free standing silver film with no hole on the optical axis and double-sided concentric corrugations. In a numerical experi ment we analyze the nanolens performance, that is transmission and focusing of radially polarized beams of different full widths at half maximum and wavelengths from the visible range. Corrugations of the front surface couple incident light to surface plasmons and those on the back surface allow efficient reradiation. The silver lens of thickness 100 nm has five concentric corrugations of periodicity 500 nm with groove depth and width equal 40 nm and 100 nm, respectively. Focusing properties of such a structure are analyzed and optimized for wavelengths in the range from 400 to 600 nm. At intensity transmission of 10-25% of incident light achievable focal spot areas reach down to 0.15 O 2 . For different illumination parameters the nanolens has focal lengths from 1 to 2 wavelengths. Without contribution of evanescent waves it focuses a far-field source into a far-field spot. The nanolens acts like a refractiv e optical system of high numerical aperture close to unity. Nanolenses of this kind can be used as light couplers in nanooptics. Keywords: Plasmonics, nanooptics, nanolens, radial polarization, optical resolution.

Propagation of continuous-wave (CW) Gaussian beams through a RHM-LHM interface as well as a metamaterial slab or a metallo-dielectric stack is subject to both spatial filtering and dispersive reshapement. Spatial filtering is polarisation-dependent and results from diraction, multiple reflections, and multiple positive or negative refractions on the layer boundaries. Structures with a broad and flat transmission spatial spectrum are capable of imaging with resolution exceeding the diraction limit. Due to strong Drude-type dispersion and absorption of the layers, it is possible to identify higher order dispersion eects taking place within very short distances. This opens the possibility of designing novel filters for joint reshaping of the spatial and temporal pulse envelopes. In the present work, we analyse the transmission of time-modulated CW Gaussian beam through structures with dispersive and lossy layers. Depending on beam divergence and the attenuation strength of the layers, the dominant eect may be identified as one-dimensional propagation with absorption and dispersion, negative refraction with dispersive modulation of the wavefront, or two-dimensional diractive focusing. We propose a theoretical model to explain the interplay of the observed spatial and dispersive phenomena. In the near diraction field pulses are reshaped and broadened. The slopes of the pulses become aected with side-lobes, and with a probable presence of superluminal eects. It is shown that the second-order dispersion eects do not yet provide a suciently accurate model for the pulse evolution. The simulations rely on a rigorous quasi-analytical planewave-based model of propagation. Transfer Matrix method (TMM) is used for numerical calculations.

We analyse the silver multilayer superlens as a modulating photonic device for spatial reshapment of circularlypolarised light beams. The silver ”at lens of Pendry and its generalisations to multilayer structures have beenprimarily introduced for in-plane perfect near-“eld imaging that includes a limited range of evanescent spatialharmonics of the “eld. In this paper, using the fully vectorial transfer matrix method we analyse the two-dimensional impulse response of the imperfect superlens for spatial and temporal “ltering of the optical signaland on this basis investigate the way it modi“es the shape of the beam.Keywords: metamaterials, layered structures, “ltering, pulse shaping 1. INTRODUCTION The early idea of perfect imaging with a left-handed metamaterial (LHM) slab comes from Veselago 1 whostudied theoretically the properties of materials with a negative real part of both permittivity and permeability.He predicted some of their unusual properties such as the reversed Snells law which leads to the convention ofselecting the negative sign for the refractive index, as well as reversed Doppler shift and Cherenkov radiationetc. The ”at lens of Veselago consists of a metamaterial slab that is impedance matched to the surroundingmaterial, eg. air, and due to the negative dirac tion in LHM allows for exact compensation of phase during lightpropagation through the device. Moreover, also the evanescent waves are subject to amplitude enhancementin the LHM. Therefore, the imaging through the Veselago material is, at least theoretically, truly lossless andabberationless. Following the theoretical works of Pendry et al.

We present a review of recent achievements in nanoscale optical devices based on energy transport with surface plasmon-polaritons and localized surface plasmons. Chains of metal subwavelength-size particles and stripes are used to build straight waveguides, s-bends, y-junctions and beam shaping devices. Strong enhancement of near-field in nanogaps between particles leads to efficient light emission from such nanoantennas. Development of surface plasmon nanoptics stimulates further progress in near-field imaging. To improve resolution of scanning near-field optical microscope (SNOM) it is necessary to improve light throughput in tapered metal-coated SNOM probes. This is achievable due to resonant surface plasmons that propagate in corrugated probes.

Wave fronts of a Gaussian light pulse and a CW Gaussian beam refracted at the boundary of right- and left-handed media are modified due to material dispersion. Group velocity of a negatively refracted pulse is parallel to the direction of energy transport and anti-parallel to phase velocity. Positively refracted group front moves sideways with respect to negatively refracted phase front. We analyze modifications of light pulses of different spectra in effective media with different frequency dispersion curves. Analysis of dispersion effects is important because of possible applications in band separation and pulse compression in metamaterial devices. In 2D FDTD simulations we analyze evolution of CW Gaussian beams and short Gaussian pulses in an effective double negative material with dependence of permittivity and permeability functions on frequency corresponding to Drude material-dispersion model.

Using the transfer matrix method we analyse the transmission of time-modulated Gaussian beam through the RHM-LHM layered structures with dispersive, lossy, and magnetic layers. The modulated parts of the beam are subject to a complex temporal and spatial shape transformation, which may be characterised in terms of spectral and spatial filtering, while the layered structure itself is entirely described with the respective transfer function or equivalently with the impulse response. Due to strong dispersion and absorption of the LHM layers, it is possible to identify higher order dispersion effects taking place within very short distances. This opens the possibility of designing novel filters capable of complex reshaping of the beam envelope.

We present recent achievements in fabricating a two-dimensional (2D) photonic crystal in the form of a bundle of parallel micro- or nanowires embedded in glass matrix. The method is similar to that of sequential thinning used for fabrication of photonic crystal fibers. We discuss technological issues that aim at preservation of regularity of photonic crystal lattice and uniformity of wire diameters. Proper selection of a melting point of metal alloy and the range of temperatures of glass viscosity leads to reduction of regularity losses resulting from sequential processes of drawing. Measured distributions of crystal lattices, wire diameters and shapes of wires are used to simulate photonic band structure of fabricated crystals. This work is directed toward fabrication of a photonic crystal showing the negative refraction in the near infrared and visible spectral range.

In this paper we report on limits related to the development of optical fibers with glass subwavelength inclusions incorporated into the core. We present the fabrication of a photonic crystal fiber made of an in-house developed silicate NC21 glass with a subwavelength-size high refractive index inclusion in the core made of lead silicate SF6 glass. The core has a diameter of 2 µm, while the diameter of the inclusion varies from 0 to 800 nm. Using energy-dispersive X-ray spectroscopy technique we show a dramatic change in the inclusion profile and its composition caused by a non-uniform diffusion of chemical molecules during the stack-and-draw fiber fabrication process. Therefore, the effective refractive index and the material dispersion of the final fiber are significantly different than for bulk glasses, which leads to an alteration of optical properties of the final fiber. A unique non-monotonic characteristic of the effective material dispersion is used to reproduce the fiber dispersion characteristic.

Current interest in photonic nanodevices motivates search for efficient transport of energy in plasmon waveguides. Chains of nanoelements made of noble metals guide light in channels of below-the-diffraction-limit size due to surface plasmon coupling. We calculate attenuation factors in a chain of parallel pairs of nanoplates for visible and near infrared range of wavelengths. Nanoplates are embedded in a medium with refractive index reaching n = 1.5. Advantages of the proposed waveguide are its small size and tunability by adjustment of geometrical parameters. However, the waveguide highly attenuates signals due to radiation into the far field and internal damping. For 595 nm wavelength, the energy transmission of 2 micrometers long chain of parallel nanoplates reaches 39%.We use the finite difference time domain (FDTD) method to investigate properties of a waveguide illuminated with polarized light. The permittivity of silver is described by Drude model. The simulation area is 780times1400times2225 nm discretized with Deltar = 5 nm step surrounded by 10 layers of UPML absorbing conditions at all boundaries. Simulation time step is Deltat = 8.34middot10-18 s. The source has a Gaussian field distribution with half width 372 nm. The source is introduced with total/scattered field split of simulation volume. Theoretically, for the wavelength of 514.5 nm the intensity of surface plasmons propagating on an infinite smooth surface decreases to 37% of its initial value after 22 mum. Our result confirms the prediction that transmission in a waveguide made of discrete plates is considerably smaller. A sample result where z-axis component of the Poynting vector calculated at a cross-section plane of the waveguide at half height is depicted. The output beam has a distinct central maximum with small side lobes in the x-axis direction

A metamaterial composed of electromagnetically active cells with two parallel wires of sub-wavelength size can be fabricated by means of patterning techniques used in microelectronics [1, 2]. Intensity transmittance of layered metamaterial is assessed as a function of fill factor, that is a ratio of wire to layer surfaces, that in simulations changes from 6 to 20%. Negative refractive index reaching as low as - 0.5 is predicted in the range of 1.13 ? 1.29 µ m for fill factor 12%. Then in FDTD simulations we analyze propagation of light through single and multiple layers of the metamaterial. A single layer exhibits a negative index of refraction at wavelengths for which absorption results from a high imaginary value of n. FDTD simulations show that the negative n should appear for the range of 1.92 ? 2.19 µ m. Theoretical underassessment of the range of wavelengths where n is negative comes from simplicity of the considered dipole model. We conclude that the smaller is the fill factor, the narrower the range of frequencies, where n is negative. Then, the smaller is the fill factor, the less negative is n. Finally, transmission considerably decreases with increasing fill factor.

We examine the propagation of energy along chains of silver nanoelements oriented perpendicularly to the flow of light and ordered in several ways. The first chain is composed ofvertical silver nanorods arranged in a hexagonal lattice. The second one consists of vertical elongated nanoplates that form a herring-bone pattern. In the third, distribution of vertically oriented nanoplates recalls footsteps. The chains are embedded in a medium with refractive index n = 1 and 1.5. Incident polarized Gaussian beams propagate along chains of nanoelements and have electric field components oriented transversally with respect to the vertical nanoelements. Transport of energy is investigated with the Finite Difference Time Domain (FDTD) method for visible and infrared range ofwavelengths, where the Drude model is valid. Propagation constants and attenuation factors are calculated. Losses are due to absorption in metal and light scattering on structure elements. In the analyzed structures, energy is transported due to localized surface plasmons-polaritons, where the amplitude of optical fields is locally enhanced by orders of magnitude. This property might be useful in the construction of nanoscale photonic devices. The smaller the metallic elements are, the stronger is the concentration of energy. Waveguides of that form may be used for creating a medium with novel effective electromagnetic properties.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Interest in photonic nanodevices motivates search for efficient transport of energy in plasmon waveguides. Chains of silver nanoelements guide light in channels of below-the-diffraction-limit size due to surface plasmon coupling. We calculate attenuation factors in chains with several geometries of nanoplates using the Finite Difference Time Domain (FDTD) method for visible and near infrared range of wavelengths, where the Drude model of dispersion is valid. Nanoplates considered in simulations are 1 micrometer high, 50 nm thick and 380 nm long and are embedded in a medium with refractive index reaching n = 1.5. Advantages of proposed waveguides are connected with their small size and possible tuneability by adjustment of geometrical parameters. However, the waveguides highly attenuate signals due to radiation into the far field and internal damping. For the optimum considered geometry and 595 nm wavelength, the energy transmission of 2 micrometers long chain of parallel nanoplates reaches 39%.

An interest in energy transport in 3D chains of metal nanoparticles is oriented towards future applications in nanoscale optical devices. We consider plasmonic waveguides composed of silver nanoplates arranged in several geometries to find the one with the lowest attenuation. We investigate light propagation of 500-nm wavelength along different chains of silver nanoplates of subwavelength length and width and wavelength-size height. Energy transmission of the waveguides is analysed in the range of 400–2000 nm. We find that chain of short parallel nanoplates guides energy better than two electromagnetically coupled continuous stripes and all other considered nonparallel structures. In a wavelength range of 500–600 nm, this 2-μm long 3D waveguide transmits 39% of incident energy in a channel of λ × λ/2 cross section area.

A metal-in-dielectric metamaterial structure different from that composed of split-ring-resonators and wire units was proposed. 1-4 The metamaterial layer is composed of randomly distributed parallel pairs of nanowires of subwavelength size that form electromagnetically active units. It was predicted that the metamaterial should exhibit macroscopic negative refraction.2'3 In a recent paper 4 fabrication of the metamaterial in the form of periodic array of parallel golden nanorods with trapezoidal cross section was reported and a negative refractive index of n = -0.3 was observed at a wavelength 1.5 μm (200 THz). In this paper we simulate response of a single pair of nanowires to near-infrared illumination and observe surface plasmon resonances using FDTD method. We simulate light propagation through the metamaterial slab made of one, two and three layers. In each layer the nanowires cover 10% of the surface. In simulations made for a single layer medium, negative refraction is observed for wavelengths from 1.55 to 2.1 μm, with Δλλ ≃ 0.3. When the number of layers increases, the range of negatively refracted wavelengths becomes narrower. For a narrow range of wavelengths that are close to the resonant frequency the intensity transmission of three layers reaches -7dB for the angle of incidence of 10°. Then layers with two orientations of nanowires are considered. In the first stack of layers all nanowires are oriented in parallel. This configuration assures plasmon resonances for both the electric and magnetic components of electromagnetic wave in all layers. In the second stack, nanowires in two subsequent layers are oriented perpendicularly. In the second layer, the plasmon resonance for the electric component of light is due to the oblique incidence of light. For a small angle of incidence of a near infrared narrow Gaussian beam we calculate two characteristics: the attenuation vs. wavelength and the lateral shift of the beam on the plane-parallel slab vs. wavelength. For a narrow range of wavelengths simulations show negative refraction of a beam incident the plane of the nanowires and a corresponding shift in the far field.

A metamaterial with an electromagnetically active single unit composed of two parallel nanowires was recently proposed by Sarychev and his collaborators. One layer of the anisotropic metamaterial contains a randomly distributed set of oriented wires that cover 10% of the layer surface. It was noted that a multilayer structure of the metamaterial should exhibit macroscopic negative refraction. Here, in the computer refraction experiment we confirm that expectation. In FDTD simulations we analyze propagation of near infrared light through the metamaterial slab. We simulate performance of a single layer illuminated normally and of a few layers illuminated at a small angle. Electric field of the illuminating Gaussian beam lies in the plane of incidence that is parallel to the direction of oriented pairs of wires. For a small angle of incidence we calculate two characteristics: the attenuation versus wavelength and the lateral shift of beam on the plane-parallel slab versus wavelength. According to our model, negative refraction should be observed for a narrow range of wavelengths around 2.85 /spl mu/m. In simulations made for a single layer medium, negative refraction is observed for wavelengths /spl lambda/ from 1.55 to 2.1 /spl mu/m, with /spl Delta//spl lambda///spl lambda//spl ap/0.3. When the number of layers increases, the range of negatively refracted wavelengths becomes narrower. In the metamaterial slab composed of three layers attenuation of the Gaussian beam of wavelengths /spl lambda/=1.2-1.55 /spl mu/m and incident at 10/spl deg/ changes from -13 to -25 dB, respectively.