Quasi-3D plasmonic coupling scheme for near-field optical lithography and imaging.
TL;DR: This work shows a novel quasi-3D plasmonic scheme to focus light into the extreme subwavelength region in the near field with an efficiency orders higher than NSOM and opens the door to many applications, such as optical lithography, nanoscale imaging, heat-assisted magnetic recording, plAsmon-enhanced Raman spectroscopy, etc.
Abstract: Near-field optical imaging and lithography rely on achieving both high resolution and efficient coupling. Particularly conventional near-field scanning optical microscopy (NSOM) suffers from the trade-off between resolution and efficiency. Planar plasmonic lens schemes can partially solve this issue utilizing plasmonic resonances, but the performance is not robust over a large range of sample materials. In this work we show a novel quasi-3D plasmonic scheme to focus light into the extreme subwavelength region in the near field with an efficiency orders higher than NSOM. The superb performance comes from the strong coupling between the localized mode with an off-plane E-field component and the sample being processed. Our scheme can efficiently focus light to a spot with a diameter down to 1/20 of its wavelength, and the coupling efficiency can be as high as 10%. Theoretically, we demonstrate that the FWHM of the focus spot can be 7 nm with an enhancement of about 800 at the UV region. The focusing performance is constantly good over a large variety of materials and the illumination and collection imaging scheme has been demonstrated by simulation. An example design of this quasi-3D coupling scheme is fabricated and its imaging performance is characterized by the apertureless optical near-field measurement. The high coupling efficiency at extreme subwavelength resolution of this quasi-3D coupling scheme opens the door to many applications, such as optical lithography, nanoscale imaging, heat-assisted magnetic recording, plasmon-enhanced Raman spectroscopy, etc.
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TL;DR: In this article, the authors provide a comprehensive overview on ordered nanostructure arrays for energy applications, focusing on how to develop efficient devices via theoretical simulation and structural optimization, and a brief introduction of techniques for realizing ordered nanoscale arrays and then recent progress on energy related devices equipped with such advanced architectures will be reviewed.
64 citations
TL;DR: In this paper, the authors discuss the recent advances in top-down nanofabrication methods towards single-digit-nanometer-sized structures and discuss state-of-the-art applications for sub-10 nm nanophotonics such as optical trapping or sensing devices, imaging devices, and electronic devices.
Abstract: Sub-10 nm nanostructures have received broad interest for their intriguing nano-optical phenomena, such as extreme field localization and enhancement, quantum tunneling effect, and strong coupling. The range of cutting-edge applications based on single-digit-nanometer scale structures has expanded with the development of nanofabrication technologies. However, challenges still remain in overcoming fabrication limits, such as scalability, controllability, and reproducibility for further practical applications of the sub-10 nm nanostructures. In this review, we discuss the recent advances in top-down nanofabrication methods towards single-digit-nanometer-sized structures. The well-known examples include electron beam lithography (EBL), focused ion beam (FIB) milling or lithography, atomic layer deposition (ALD), and other unconventional techniques to obtain sub-10 nm nanostructures or nanogaps. We discuss state-of-the-art applications for sub-10 nm nanophotonics such as optical trapping or sensing devices, imaging devices, and electronic devices.
32 citations
TL;DR: This work presents the review of recent achievements in experimental and theoretical studies of metal-dielectric micro and nano antennae that are important for fundamental and applied research and proposes new plasmonic structures for various applications.
Abstract: Metal-dielectric micro/nano-composites have surface plasmon resonances in visible and near-infrared domains. Excitation of coupled metal-dielectric resonances is also important. These different resonances can allow enhancement of the electromagnetic field at a subwavelength scale. Hybrid plasmonic structures act as optical antennae by concentrating large electromagnetic energy in micro- and nano-scales. Plasmonic structures are proposed for various applications such as optical filters, investigation of quantum electrodynamics effects, solar energy concentration, magnetic recording, nanolasing, medical imaging and biodetection, surface-enhanced Raman scattering (SERS), and optical super-resolution microscopy. We present the review of recent achievements in experimental and theoretical studies of metal-dielectric micro and nano antennae that are important for fundamental and applied research. The main impact is application of metal-dielectric optical antennae for the efficient SERS sensing.
26 citations
Cites background from "Quasi-3D plasmonic coupling scheme ..."
...have demonstrated the production of a longitudinal electric field with metallic LFDT composed of plasmonic lenses [230]....
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TL;DR: A high-performance multi-resonance plasmonic sensor with double-layer metallic grooves is theoretically constructed by introducing a polymethyl methacrylate groove with a numerical simulation method, and three resonance dips for sensing can be generated in the reflection spectrum to realize three-channel sensing measurement.
Abstract: A high-performance multi-resonance plasmonic sensor with double-layer metallic grooves is theoretically constructed by introducing a polymethyl methacrylate groove with a numerical simulation method. Multiple resonance wavelengths can be generated at the oblique incidence, and the number and feature of resonant mode for sensing detection is different for various incident angles. Specifically, at the incident angle of 30°, the reflection spectrum exhibits two resonant dips, in which the dip at the wavelength of 1066 nm has an extremely narrow line width of ~4.5 nm and high figure of merit of ~111.11. As the incident angle increases, the electric dipole mode gradually weakens, but the surface plasmon resonance and cavity resonance mode are enhanced. Therefore, for an incident angle of 65°, three resonance dips for sensing can be generated in the reflection spectrum to realize three-channel sensing measurement. These double-layer plasmonic grooves have potential in the development of advanced biochemical surface plasmon polariton measurements.
11 citations
TL;DR: In this article, the optical properties of a TiN/(Al,Sc)N superstructures deposited on MgO substrates were studied by using first principles approaches, and the modifications of the plasmonic response of ultrathin TiN layers were interpreted at the microscopic level, in terms of the electronic structure of the TiN/dielectric interfaces.
Abstract: The optical properties of a TiN/(Al,Sc)N superstructures deposited on MgO substrates are studied by using first principles approaches. The modifications of the plasmonic response of ultrathin TiN layers when faced to MgO and nitride surfaces are interpreted at the microscopic level, in terms of the electronic structure of the TiN/dielectric interfaces. The hyperbolic behavior of the multi-stacked metamaterial, described both via the effective medium theory and first principles simulations of periodic TiN/(Al,Sc)N superlattices, is closely investigated and directly compared to recent experimental results. The latter comparison underlines the crucial role of quantum confinement especially for the ultrathin dielectric layers.
9 citations
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TL;DR: In this paper, the diffraction of electromagnetic radiation by a hole small compared with the wave-length is treated theoretically, and a complete solution is found satisfying Maxwell's equations and the boundary conditions everywhere.
Abstract: The diffraction of electromagnetic radiation by a hole small compared with the wave-length is treated theoretically. A complete solution is found satisfying Maxwell's equations and the boundary conditions everywhere (Section 4). The solution holds for a circular hole in a perfectly conducting plane screen, but it is believed that the method will be applicable to much more general problems (Section 8). The method is based on the use of fictitious magnetic charges and currents in the diffracting hole which has the advantage of automatically satisfying the boundary conditions on the conducting screen. The charges and currents are adjusted so as to give the correct tangential magnetic, and normal electric, field in the hole. The result (Section 5) is completely different from that of Kirchhoff's method, giving for the diffracted electric and magnetic field values which are smaller in the ratio (radius of the hole/wave-length) (Section 6). The diffracted field can be considered as caused by a magnetic moment in the plane of the hole, and an electric moment perpendicular to it (Section 6). The theory is applied to the problem of mutual excitation of cavities coupled by small holes (Section 9). This leads to equations very similar to those for ordinary coupled circuits. The phase and amplitude relations of two coupled cavities are not uniquely determined, but there are two modes of oscillation, of slightly different frequency, for which these relations are opposite (Section 10). The problem of stepping up the excitation from one cavity to another is treated (Section 11).
2,562 citations
TL;DR: This work used Drosophila melanogaster larvae to develop a high-throughput whole organism screen for drugs that modulate food intake and identified the serotonin (5-hydroxytryptamine or 5-HT) receptor antagonist metitepine as a potent anorectic drug.
Abstract: Dysregulation of eating behavior can lead to obesity, which affects 10% of the adult population worldwide and accounts for nearly 3 million deaths every year. Despite this burden on society, we currently lack effective pharmacological treatment options to regulate appetite. We used Drosophila melanogaster larvae to develop a high-throughput whole organism screen for drugs that modulate food intake. In a screen of 3630 small molecules, we identified the serotonin (5-hydroxytryptamine or 5-HT) receptor antagonist metitepine as a potent anorectic drug. Using cell-based assays we show that metitepine is an antagonist of all five Drosophila 5-HT receptors. We screened fly mutants for each of these receptors and found that serotonin receptor 5-HT2A is the sole molecular target for feeding inhibition by metitepine. These results highlight the conservation of molecular mechanisms controlling appetite and provide a method for unbiased whole-organism drug screens to identify novel drugs and molecular pathways modulating food intake.
2,329 citations
TL;DR: A periodic texture on the exit side of a single aperture in a metal film is created and, when combined with enhanced transmission, suggests that a wide range of photonic applications is possible.
Abstract: Light usually diffracts in all directions when it emerges from a subwavelength aperture, which puts a lower limit on the size of features that can be used in photonics. This limitation can be overcome by creating a periodic texture on the exit side of a single aperture in a metal film. The transmitted light emerges from the aperture as a beam with a small angular divergence (approximately ±3°) whose directionality can be controlled. This finding is especially surprising, considering that the radiating region is mainly confined to an area with lateral dimensions comparable to the wavelength of the light. The device occupies no more than one cubic micrometer and, when combined with enhanced transmission, suggests that a wide range of photonic applications is possible.
1,795 citations
TL;DR: In this paper, the authors describe the fundamentals of scanning near-field optical microscopy with aperture probes, including instrumentation and probe fabrication, aspects of light propagation in metal-coated, tapered optical fibers, and field distributions in the vicinity of subwavelength apertures.
Abstract: In this review we describe fundamentals of scanning near-field optical microscopy with aperture probes. After the discussion of instrumentation and probe fabrication, aspects of light propagation in metal-coated, tapered optical fibers are considered. This includes transmission properties and field distributions in the vicinity of subwavelength apertures. Furthermore, the near-field optical image formation mechanism is analyzed with special emphasis on potential sources of artifacts. To underline the prospects of the technique, selected applications including amplitude and phase contrast imaging, fluorescence imaging, and Raman spectroscopy, as well as near-field optical desorption, are presented. These examples demonstrate that scanning near-field optical microscopy is no longer an exotic method but has matured into a valuable tool.
726 citations
TL;DR: The affiliation was incorrectly listed as “Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China”, and the correct affiliation is listed above.
Abstract: Methylacetoin (3-hydroxy-3-methylbutan-2-one) and 2-methyl-2,3-butanediol are currently obtained exclusively via chemical synthesis. Here, we report, to the best of our knowledge, the first alternative route, using engineered Escherichia coli. The biological synthesis of methylacetoin was first accomplished by reversing its biodegradation, which involved modifying the enzyme complex involved, switching the reaction substrate, and coupling the process to an exothermic reaction. 2-Methyl-2,3-butanediol was then obtained by reducing methylacetoin by exploiting the substrate promiscuity of acetoin reductase. A complete biosynthetic pathway from renewable glucose and acetone was then established and optimized via in vivo enzyme screening and host metabolic engineering, which led to titers of 3.4 and 3.2 g l−1 for methylacetoin and 2-methyl-2,3-butanediol, respectively. This work presents a biodegradation-inspired approach to creating new biosynthetic pathways for small molecules with no available natural biosynthetic pathway.
535 citations