Xiangang Luo

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (220)504.01 Total impact

  • Xianchao Liu · Xiong Li · Ling Li · Weidong Chen · Xiangang Luo ·

    Optics Express 11/2015; 23(23):30136. DOI:10.1364/OE.23.030136 · 3.49 Impact Factor
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    Scientific Reports 10/2015; 5:15781. DOI:10.1038/srep15781 · 5.58 Impact Factor
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    ABSTRACT: For near-field imaging optics, minimum resolvable feature size is highly constrained by the near-field diffraction limit associated with the illumination light wavelength and the air distance between the imaging devices and objects. In this study, a plasmonic cavity lens composed of Ag-photoresist-Ag form incorporating high spatial frequency spectrum off-axis illumination (OAI) is proposed to realize deep subwavelength imaging far beyond the near-field diffraction limit. This approach benefits from the resonance effect of the plasmonic cavity lens and the wavevector shifting behavior via OAI, which remarkably enhances the object's subwavelength information and damps negative imaging contribution from the longitudinal electric field component in imaging region. Experimental images of well resolved 60-nm half-pitch patterns under 365-nm ultra-violet light are demonstrated at air distance of 80 nm between the mask patterns and plasmonic cavity lens, approximately four-fold longer than that in the conventional near-field lithography and superlens scheme. The ultimate air distance for the 60-nm half-pitch object could be theoretically extended to 120 nm. Moreover, two-dimensional L-shape patterns and deep subwavelength patterns are illustrated via simulations and experiments. This study promises the significant potential to make plasmonic lithography as a practical, cost-effective, simple and parallel nano-fabrication approach.
    Scientific Reports 10/2015; 5. DOI:10.1038/srep15320 · 5.58 Impact Factor
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    ABSTRACT: The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a " true mathematical and mechanical form " in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of meta-surfaces to produce continuous and linear phase shift covering [0, 2pi], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics , our approach would allow the complete control of photons within a single nanometric layer.
    Science Advances 10/2015; 1(9):e1500396. DOI:10.1126/sciadv.1500396
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    ABSTRACT: Nanofabrication technology with high-resolution, high-throughput and low-cost is essential for the development of nanoplasmonic and nanophotonic devices. At present, most metasurfaces are fabricated in a point by point writing manner with electron beam lithography or a focused ion beam, which imposes a serious cost barrier with respect to practical applications. Near field optical lithography, seemingly providing a high-resolution and low-cost way, however, suffers from the ultra shallow depth and poor fidelity of obtained photoresist patterns due to the exponential decay feature of evanescent waves. Here, we propose a method of surface plasmonic imaging lithography by introducing a reflective plasmonic lens to amplify and compensate evanescent waves, resulting in the production of nano resist patterns with high fidelity, contrast and enhanced depth beyond that usually obtained by near field optical lithography. As examples, a discrete and anisotropically arrayed nano-slots mask pattern with different orientations and a size of 40 nm × 120 nm could be imaged in photoresist and transferred successfully onto a metal layer through an etching process. Evidence for the pattern quality is given by virtue of the fabricated meta-surface lens devices showing good focusing performance in experiments. It is believed that this method provides a parallel, low-cost, high-throughput and large-area nanofabrication route for fabricating nano-structures of holograms, vortex phase plates, bio-sensors and solar cells etc.
  • Kai Yan · Ling Liu · Na Yao · Kaipeng Liu · Wenjuan Du · Wei Zhang · Wei Yan · Changtao Wang · Xiangang Luo ·

    Plasmonics 09/2015; DOI:10.1007/s11468-015-0081-5 · 2.24 Impact Factor
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    ABSTRACT: Conventional optics is diffraction limited due to the cutoff of spatial frequency components, and evanescent waves allow subdiffraction optics at the cost of complex near-field manipulation. Recently, optical superoscillatory phenomena were employed to realize superresolution lenses in the far field, but suffering from very narrow working wavelength band due to the fragility of the superoscillatory light field. Here, an ultrabroadband superoscillatory lens (UBSOL) is proposed and realized by utilizing the metasurface-assisted law of refraction and reflection in arrayed nanorectangular apertures with variant orientations. The ultrabroadband feature mainly arises from the nearly dispersionless phase profile of transmitted light through the UBSOL for opposite circulation polarization with respect to the incident light. It is demonstrated in experiments that subdiffraction light focusing behavior holds well with nearly unchanged focal patterns for wavelengths spanning across visible and near-infrared light. This method is believed to find promising applications in superresolution microscopes or telescopes, high-density optical data storage, etc.
    Laser & Photonics Review 09/2015; DOI:10.1002/lpor.201500182 · 8.01 Impact Factor
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    ABSTRACT: Metasurface provides extreme flexibility to manipulate the phase, polarization and amplitude of electromagnetic wave. By employing the abrupt phase shift in plasmonic nano-antenas, here we present an ultra-thin planar metalens for the azimuthally (or radially) polarized light illumination to obtain a focal spot (or doughnut-shaped focus). The designed metalens exhibits broadband frequency response at frequencies ranging from 300 to 400 THz. In addition, a tight spot size (0.47λ) is obtained when designed metalens with inner opaque annulus is illuminated by the azimuthally polarized light with wavelength 857 nm. It is expected that our scheme has potential applications in beam trapping, particle acceleration, integrated optics and super-resolution imaging.
    Optics Communications 08/2015; 356:445-450. DOI:10.1016/j.optcom.2015.08.025 · 1.45 Impact Factor
  • Weiguo Chen · Jiong Wang · Zeyu Zhao · Changtao Wang · YanQin Wang · Na Yao · Xiangang Luo ·
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    ABSTRACT: A new method is proposed to focus azimuthally polarized beam into an ultra-small or ultra-big dark spot under high numerical aperture lens system. Manipulated by proper designed binary 0-π phase plate, an ultra small dark spot regardless of side-lobe intensity is generated with main-lobe peak to peak distance shrunk to 0.24λ, which is 46% of the case without phase plate. For potential applications, shrinking the dark spot and suppressing the side-lobe intensity are analyzed, and several cases of squeezed dark spots with different levels of side-lobe intensities are presented. Additionally, using a two-zone phase plate to enlarge the dark spot is investigated in this paper, and an enlarged dark spot is readily acquired with the main-lobe peak to peak distance in a range of 100%–200%. The advantages of this method are its large scale manipulation of the dark spot size and its high performance in suppressing side-lobe intensity, which is of great worth in enhancing the performance of many systems such as optical tweezers and stimulated emission depletion (STED) microscope.
    Optics Communications 08/2015; 349. DOI:10.1016/j.optcom.2015.03.024 · 1.45 Impact Factor
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    Min Wang · Cheng Huang · Mingbo Pu · Xiangang Luo ·
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    ABSTRACT: A method of utilizing frequency selective surface (FSS) to reduce side lobe level (SLL) is proposed. The FSS composed of annular slot arrays loaded with resistors is divided into several regions along the electric field direction. Each region has difference transmission amplitude (TA) but the same transmission phase (TP). Through the appropriate distribution design for each region, the output wave with tapered TA and uniform TP is obtained when the FSS is illuminated by a plane wave. Thus the FSS could be utilized to reduce the antenna SLL. An H-plane sectorial horn array is adopted as an exciting source to validate its SLL reduction performance. Simulation results show that the proposed FSS superstrate makes the SLL of the horn array in the E-plane desirably suppressed from −12.4 to −25.9 dB at 10.3GHz with the gain reduced from 18.3 to 16.7 dBi. The measured results agree well with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1971–1975, 2015
    Microwave and Optical Technology Letters 08/2015; 57(8). DOI:10.1002/mop.29240 · 0.57 Impact Factor
  • Xiantao Zhang · Lianshan Yan · Yinghui Guo · Wei Pan · Bin Luo · Xiangang Luo ·

    Plasmonics 07/2015; DOI:10.1007/s11468-015-0029-9 · 2.24 Impact Factor
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    ABSTRACT: The orbital angular momentum (OAM) of light, as an emerging hotspot in optics and photonics, introduces many degrees of freedom for applications ranging from optical communication and quantum processing to micromanipulation. To achieve a high degree of integration, optical circuits for OAM light are essential, which are, however, challenging in the optical regime owing to the lack of well-developed theory. Here we provide a scheme to guide and collimate the OAM beam at the micro- and nano-levels. The coaxial plasmonic slit was exploited as a naturally occurring waveguide for light carrying OAM. Concentric grooves etched on the output surface of the coaxial waveguide were utilized as a plasmonic metasurface to couple the OAM beam to free space with greatly increased beam directivity. Experimental results at λ = 532 nm validated the novel transportation and collimating effect of the OAM beam. Furthermore, dynamic tuning of the topological charges was demonstrated by using a liquid crystal spatial light modulator (SLM).
    Scientific Reports 07/2015; 5:12108. DOI:10.1038/srep12108 · 5.58 Impact Factor
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    Xiangang luo · Mingbo Pu · Xiaoliang Ma · Xiong Li ·
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    ABSTRACT: As two-dimensional metamaterials, metasurfaces have received rapidly increasing attention from researchers all over the world. Unlike three-dimensional metamaterials, metasurfaces can be utilized to control the electromagnetic waves within one infinitely thin layer, permitting substantial advantages, such as easy fabrication, low cost, and high degree of integration. This paper reviews the history and recent development of metasurfaces, with particular emphasis on the theory and applications relating to the frequency response, phase shift, and polarization state control. Based on the current status of various applications, the challenges and future trends of metasurfaces are discussed.
    International Journal of Antennas and Propagation 06/2015; 2015(16):204127. DOI:10.1155/2015/204127 · 0.66 Impact Factor
  • Jiao Jiao · Xiong Li · Xiaoping Huang · Qing Zhao · Xiangang Luo ·
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    ABSTRACT: Lens is usually immersed into oil or other mediums to increase the numerical aperture of the focusing lens and significantly improve the focusing efficiency. V-shaped plasmonic lens has attracted many research attentions because of its advantages like ability of reduced spherical aberration, ultrathin thickness, simple design, and high adjustability. However, it is hard to apply in practice since the focusing ability of such lens is low and errors can be great. Based on the incident light which wavelength is 1.5 μm, a V-shaped plasmonic planar lens with a thickness of 30 nm is designed, and it is immersed into the medium at a refractive index of 1 to 2.5. By matching conditions of transverse wave vector and Rayleigh limit formula, when the refractive index of mediums increases, the focusing efficiency becomes stronger, the spatial resolution is higher, and the focusing spot is changed. Through this easy-to-handle method, the significant focusing effect can be obtained, and this method promotes the applications of planar focusing lens in optical focusing, optical storage, laser-writing, and miniature optical integrated devices.
    Plasmonics 06/2015; 10(3). DOI:10.1007/s11468-014-9838-5 · 2.24 Impact Factor
  • Yiguo Chen · Xiong Li · Xiangang Luo · Stefan A. Maier · Minghui Hong ·
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    ABSTRACT: A tunable plasmonic perfect absorber with a tuning range of ∼650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration. The absorption at the plasmonic resonance is kept above 0.96 across the whole tuning range. In this work we study this extraordinary optical response numerically and reveal the geometric conditions which support this phenomenon. This work shows a promising route to achieve tunable plasmonic devices for multi-band optical modulation, communication, and thermal imaging.
    Photonics Research 06/2015; 3(3). DOI:10.1364/PRJ.3.000054
  • Yaohui Wang · Na Yao · Wei Zhang · Jiayu He · Changtao Wang · Yanqin Wang · Zeyu Zhao · Xiangang Luo ·
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    ABSTRACT: We theoretically utilize bowtie aperture combined with metal-insulator-metal (MIM) scheme to obtain sub-32-nm (λ/12) high-aspect plasmonic spots. The improvement of the depth profile is attributed to the asymmetry electromagnetic mode excitation in MIM structure and the decaying compensation of the reflective Ag layer. A theoretical near-field exposure model has been used to evaluate the exposure depth in the photoresist. It is demonstrated that the exposure depth of the sub-32-nm plasmonic spot is more than 20 nm, which is about four times of the bowtie aperture without MIM scheme. The influences of the air gap tolerance and the ridge gap size of bowtie aperture are also discussed.
    Plasmonics 05/2015; DOI:10.1007/s11468-015-9966-6 · 2.24 Impact Factor
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    ABSTRACT: Data capacity is rapidly reaching its limit in modern optical communications. Optical vortex has been explored to enhance the data capacity for its extra degree of freedom of angular momentum. In traditional means, optical vortices are generated using space light modulators or spiral phase plates, which would sharply decrease the integration of optical communication systems. Here we experimentally demonstrate a planar chiral antenna array to produce optical vortex from a circularly polarized light. Furthermore, the antenna array has the ability to focus the incident light into point, which greatly increases the power intensity of the generated optical vortex. This chiral antenna array may have potential application in highly integrated optical communication systems.
    Scientific Reports 05/2015; 5:10365. DOI:10.1038/srep10365 · 5.58 Impact Factor
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    ABSTRACT: The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few.
    Scientific Reports 05/2015; 5:9822. DOI:10.1038/srep09822 · 5.58 Impact Factor
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    Fei Qin · Kun Huang · Jianfeng Wu · Jiao Jiao · Xiangang Luo · Chengwei Qiu · Minghui Hong ·
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    ABSTRACT: Flat optics, which could planarize and miniaturize the traditional optical elements, possesses the features of extremely low profile and high integration for advanced manipulation of light. Here we proposed and experimentally demonstrated a planar metalens to realize an ultra-long focal length of ~240λ with a large depth of focus (DOF) of ~12λ, under the illumination of azimuthally polarized beam with vortical phase at 633 nm. Equally important is that such a flat lens could stably keep a lateral subwavelength width of 0.42λ to 0.49λ along the needle-like focal region. It exhibits one-order improvement in the focal length compared to the traditional focal lengths of 20~30λ of flat lens, under the criterion of having subwavelength focusing spot. The ultra-long focal length ensures sufficient space for subsequent characterization behind the lens in practical industry setups, while subwavelength cross section and large DOF enable high resolution in transverse imaging and nanolithography and high tolerance in axial positioning in the meantime. Such planar metalens with those simultaneous advantages is prepared by laser pattern generator rather than focused ion beam, which makes the mass production possible.
    Scientific Reports 05/2015; 5:09977. DOI:10.1038/srep09977 · 5.58 Impact Factor
  • Xiaoyu Wu · Chenggang Hu · Min Wang · Mingbo Pu · Xiangang Luo ·
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    ABSTRACT: In this paper, we demonstrate the design of a low-scattering metamaterial shell with strong backward scattering reduction and a wide bandwidth at microwave frequencies. Low echo is achieved through cylindrical wave expanding theory, and such shell only contains one metamaterial layer with simultaneous low permittivity and permeability. Cut-wire structure is selected to realize the low electromagnetic (EM) parameters and low loss on the resonance brim region. The full-model simulations show good agreement with theoretical calculations, and illustrate that near −20dB reduction is achieved and the −10 dB bandwidth can reach up to 0.6 GHz. Compared with the cloak based on transformation electromagnetics, the design possesses advantage of simpler requirement of EM parameters and is much easier to be implemented when only backward scattering field is cared.
    Optics Express 04/2015; 23(8). DOI:10.1364/OE.23.010396 · 3.49 Impact Factor

Publication Stats

2k Citations
504.01 Total Impact Points


  • 2000-2015
    • Chinese Academy of Sciences
      • Institute of Optics And Electronics
      Peping, Beijing, China
  • 2013
    • Chongqing University
      • Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China
      Ch’ung-ch’ing-shih, Chongqing Shi, China
  • 2011-2012
    • Southwest Jiaotong University
      • School of Information Science and Technology
      Hua-yang, Sichuan, China
  • 2007-2011
    • The institute of Optics and Electronics
      Hua-yang, Sichuan, China