Superlens from complementary anisotropic metamaterials
TL;DR: In this paper, it was shown that using bilayer metamaterials that have complementary anisotropic property, the diverging waves are recombined to produce a subwavelength image, i.e., a superlens device can be designed.
Abstract: Metamaterials with isotropic property have been shown to possess novel optical properties such as a negative refractive index that can be used to design a superlens. Recently, it was shown that metamaterials with anisotropic property can translate the high-frequency wave vector k values from evanescence to propagating. However, electromagnetic waves traveling in single-layer anisotropic metamaterial produce diverging waves of different spatial frequency. In this work, it is shown that, using bilayer metamaterials that have complementary anisotropic property, the diverging waves are recombined to produce a subwavelength image, i.e., a superlens device can be designed. The simulation further shows that the design can be achieved using a metal/oxide multilayer, and a resolution of 30 nm can be easily obtained in the optical frequency range.
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TL;DR: In this article, a review of the recent progress in nanostructures for surface plasmons is presented, where the resonance modes include longitudinal and transversal resonances, dipolar and multipolar resonances and Fano resonances.
Abstract: Surface plasmons (SPs) are electromagnetic excitations existing at the interface between a metal and a dielectric material. Control and manipulation of light based on SPs at the nanometer scale offers significant advantages in nanophotonic devices with very small elements, since the peculiar properties of SPs can be tailored by construction of nanostructures with various interfaces between metals and dielectric materials. Recent progress in nanostructures for SPs is reviewed. Resonance frequencies or wavelengths of SPs can be tuned by design of metal nanostructures, such as nanoparticles, nanorods, nanowires, nanosheets, and nanodisks. Moreover, SP resonance modes can also be tuned by control of the shapes and sizes of nanostructures, where the resonance modes include longitudinal and transversal resonances, dipolar and multipolar resonances, and Fano resonances. Based on SP coupling for metal nanostructures, metal–semiconductor nanostructures, metal–dielectric nanostructures, and metal–polymer nanostructures, propagating and guiding of SP can be achieved through the metal nanostructures and the hybrid structures. Additionally, metal nanostructures exhibit remarkable field enhancement effects (e.g., local near-field enhancement, and optical transmission enhancement) due to SP coupling. Furthermore, SP nanostructures perform unique focusing and imaging characteristics at the nanometer scale beyond the diffraction limit. Tailoring SPs by control of the nanostructures is expected to be used for design and development of high-performance optical components and circuits, which offer both potential and challenges for new generations of nanophotonic devices.
111 citations
TL;DR: In this article, the effective skin-depth and resolution of Ag-TiO2, Ag-SrTiO3, and Ag-GaP multilayers for imaging with sub-wavelength resolution were optimized.
Abstract: We optimize the effective skin-depth and resolution of Ag-TiO2, Ag-SrTiO3, and Ag-GaP multilayers for imaging with sub-wavelength resolution. In terms of transmission and resolution, the optimized multilayers outperform simple designs based on combined use of effective medium theory, impedance matching and Fabry–Perot resonances. For instance, an optimized Ag-GaP multilayer consisting of only 17 layers, operating at the wavelength of 490 nm and having a total thickness equal to one wavelength, combines 78% intensity transmission with a resolution of 60 nm. It is also shown that use of the effective medium theory leads to sub-optimal multilayer designs with respect to the trade-off between the skin depth and resolution already when the period of the structure is on the order of 40 nm or larger.
34 citations
TL;DR: In this article, a thin multilayered structure with interleaved nonspherical metal-dielectric composites slices and dielectric slices was modeled as the metamaterial with anisotropic permittivity.
Abstract: A thin multilayered structure with interleaved nonspherical metal-dielectric composites slices and dielectric slices may be modeled as the metamaterial with anisotropic permittivity. The signs of diagonal elements of the permittivity tensor can be controlled by the particles' shape, the volume fraction of metal particles, and the incidental wavelengths. To one's interest, when the spheroidal nanoparticles are oblate in shape, the wavelength range in which components of the permittivity have different signs is widened, and the magnitude of optical absorption band becomes weak. Since both physical anisotropy and low absorption are helpful for improving the subwavelength image resolution, the multilayered structure containing metal-dielectric composite layer of nonspherical particles may be designed as a superlens device. In addition, the incident wavelength and the number of nanolayers are found to play crucial roles in enhancing the evanescent field performance too.
28 citations
TL;DR: In this article, a multilayered structure consisting of alternating negative permittivity and dielectric layers is explored to obtain high-resolution imaging of subwavelength objects, and wide ∞at upheavals are generated on the transmission curves so that evanescent waves in a large range are transmitted through the structures with appropriate amplitudes.
Abstract: Multilayered structures consisting of alternating negative- permittivity and dielectric layers are explored to obtain high-resolution imaging of subwavelength objects. The peaks with the smallest jkyj (ky is the transverse wave vector) on the transmission curves, which come from the guided modes of the multilayered structures, can not be completely damped by material loss. This makes the amplitudes of the evanescent waves around these peaks inappropriate after transmitted through the imaging structures, and the imaging quality is not good. To solve such a problem, the permittivity of the dielectric layers is appropriately chosen to make these sharp peaks merge with their neighboring peaks, whose corresponding guiding modes in the multilayered structure are cutofi. Wide ∞at upheavals are then generated on the transmission curves so that evanescent waves in a large range are transmitted through the structures with appropriate amplitudes. In addition, it is found that the sharp peaks with the smallest jkyj can be eliminated by adding appropriate coating layers and wide ∞at upheavals can also be obtained.
25 citations
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References
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Book•
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01 Jan 1959
TL;DR: In this paper, the authors discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals, including interference, interferometers, and diffraction.
Abstract: The book is comprised of 15 chapters that discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals. The text covers the elements of the theories of interference, interferometers, and diffraction. The book tackles several behaviors of light, including its diffraction when exposed to ultrasonic waves.
19,815 citations
[...]
01 Oct 1999
TL;DR: In this article, the authors discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals, including interference, interferometers, and diffraction.
Abstract: The book is comprised of 15 chapters that discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals. The text covers the elements of the theories of interference, interferometers, and diffraction. The book tackles several behaviors of light, including its diffraction when exposed to ultrasonic waves.
19,503 citations
TL;DR: In this paper, the optical constants for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV.
Abstract: The optical constants $n$ and $k$ were obtained for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV. The film-thickness range was 185-500 \AA{}. Three optical measurements were inverted to obtain the film thickness $d$ as well as $n$ and $k$. The estimated error in $d$ was \ifmmode\pm\else\textpm\fi{} 2 \AA{}, and that in $n$, $k$ was less than 0.02 over most of the spectral range. The results in the film-thickness range 250-500 \AA{} were independent of thickness, and were unchanged after vacuum annealing or aging in air. The free-electron optical effective masses and relaxation times derived from the results in the near infrared agree satisfactorily with previous values. The interband contribution to the imaginary part of the dielectric constant was obtained by subtracting the free-electron contribution. Some recent theoretical calculations are compared with the results for copper and gold. In addition, some other recent experiments are critically compared with our results.
17,509 citations
TL;DR: The authors' simulations show that a version of the lens operating at the frequency of visible light can be realized in the form of a thin slab of silver, which resolves objects only a few nanometers across.
Abstract: Optical lenses have for centuries been one of scientists’ prime tools. Their operation is well understood on the basis of classical optics: curved surfaces focus light by virtue of the refractive index contrast. Equally their limitations are dictated by wave optics: no lens can focus light onto an area smaller than a square wavelength. What is there new to say other than to polish the lens more perfectly and to invent slightly better dielectrics? In this Letter I want to challenge the traditional limitation on lens performance and propose a class of “superlenses,” and to suggest a practical scheme for implementing such a lens. Let us look more closely at the reasons for limitation in performance. Consider an infinitesimal dipole of frequency v in front of a lens. The electric component of the field will be given by some 2D Fourier expansion,
10,974 citations
10,495 citations