S. N. Zhu

Nanjing University, Nan-ching, Jiangsu, China

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Publications (244)655.04 Total impact

  • R. Ni · L. Du · Y. Wu · X. P. Hu · J. Zou · Y. Sheng · A. Arie · Y. Zhang · S. N. Zhu
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    ABSTRACT: In this letter, we demonstrate the realization of nonlinear Cherenkov difference-frequency generation (CDFG) exploiting the birefringence property of KTiOPO4 (KTP) crystal. The pump and signal waves were set to be along different polarizations, thus the phase-matching requirement of CDFG, which is, the refractive index of the pump wave should be smaller than that of the signal wave, was fulfilled. The radiation angles and the intensity dependence of the CDFG on the pump wave were measured, which agreed well with the theoretical ones.
    No preview · Article · Jan 2016 · Applied Physics Letters
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    ABSTRACT: We report that the optical orbital angular momentum (OAM) is conserved in the two-step cascaded nonlinear processes through quasi-phase-matched (QPM) in a dual-structure periodically poled LiTaO!(PPLT) crystal. Because of the different reciprocal vectors provided by the different structures in the crystal, collinear second harmonic (SH) beam with an OAM of l2 and third harmonic (TH) beam with an OAM of l3 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conversion law (l2 = 2l1, l3 = 3l1) holds well in this nonlinear process. Our results provide an effective way to obtain three beams (fundamental beam, SH beam, TH beam) with different OAMs at the same time, which can be used to enhance the capacity of optical communication.
    No preview · Article · Dec 2015
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    ABSTRACT: We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO3 (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l 2 are simultaneously generated by the input fundamental beam with an OAM of l 1. The OAM conservation law (i.e., l 2 = 2l 1) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications.
    No preview · Article · Oct 2015 · Applied Physics Letters
  • J. J. Yang · S. M. Wang · Q. Q. Cheng · T. Li · X. P. Hu · S. N. Zhu
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    ABSTRACT: We introduce a cross plasmonic antenna (CPA) for the system of multiple quantum emitters (QEs) with different emission wavelengths, where the excitation light scattering and emission fluorescence of different QEs are spatially separated in four different directions. By considering the CPA as oscillating dipoles, this phenomenon is attributed to the phase differences between them. The enhancement for QEs are very strong in correponding directions. In addition, the fluorescence is strongly polarized. By adding a silver plate as substrate, the directivity can be further tuned in the whole upper half space. Our result shows that the CPA is promising for realization of an efficient, directional and strongly polarized nano-scale light source, which will have potential application in Nano-Optics.
    No preview · Article · Jun 2015 · Optics Express
  • Q.Q. Cheng · Y. Pan · B.B. Xu · T. Li · S.N. Zhu
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    ABSTRACT: In the binary plasmonic waveguide array (PWA), we experimentally demonstrated a topologically protected optical mode with immunity against structural disorders, and theoretically proposed an optical analogue of massless Dirac Fermion by alternating positive and negative couplings.
    No preview · Article · May 2015
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    L. L. Lu · P. Xu · M. L. Zhong · Y. F. Bai · S. N. Zhu
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    ABSTRACT: We report a compact scheme for the generation and manipulation of photon pairs entangled in the orbital angular momentum (OAM) from the fork-poling quadratic nonlinear crystal. The χ(2)-modulation in this crystal is designed for fulfilling a tilted quasi-phase-matching geometry to ensure the efficient generation of entangled photons as well as for transferring of topological charge of the crystal to the photon pairs. Numerical results show that the OAM of photon pair is anti-correlated and the degree of OAM entanglement can be enhanced by modulating the topological charge of crystal, which indicates a feasible extension to high-dimensional OAM entanglement. These studies suggest that the fork-poling nonlinear photonic crystal a unique platform for compact generation and manipulation of high-dimensional and high-order OAM entanglement, which may have potential applications in quantum communication, quantum cryptography and quantum remote sensing.
    Full-text · Article · Jan 2015 · Optics Express
  • F Qi · Z G Feng · Y F Wang · P Xu · S N Zhu · W H Zheng
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    ABSTRACT: We introduce second-order coupling into the transport and coupling of photons in waveguide lattices. Second-order coupling, as well as high-order couplings, can be significant in long, compact or some special lattices, and is important for large-scale quantum circuits. Photon-number correlations with various amounts of second-order couplings are calculated. Some distinctive and interesting effects arise, and these are helpful for our comprehension of quantum walks in waveguide lattices.
    No preview · Article · Oct 2014 · Journal of optics
  • Y. Yang · P. Xu · L. L. Lu · S. N. Zhu
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    ABSTRACT: We propose to engineer the quantum state in a high-dimensional Hilbert space by taking advantage of a ${$\chi${}}^{(2)}$-modulated nonlinear waveguide array. By varying the pump condition and the waveguide array length, the momentum correlation between the signal and idler photons can be manipulated, exhibiting bunching, antibunching, and the evolution between these two states, which are characterized by the Schmidt number. We find the Schmidt number is dependent on a structure parameter, namely the ratio of the array length and the number of channels pumped. By designing the linear profile waveguide array, the degree of spatial entanglement shows a periodic relationship with the slope of linear profile, during which a high degree of position-bunching state is suggested. The two-photon self-focusing effect is disclosed when the ${$\chi${}}^{(2)}$ modulation in the waveguide array contains a parabolic profile, which can be designed for efficient coupling between a waveguide array and fibers. These results shed light on a feasible way to achieve desirable quantum state on a single waveguide chip by a compact engineering of ${$\chi${}}^{(2)}$ and also suggest a degree of freedom for quantum walk and other related applications.
    No preview · Article · Oct 2014 · Physical Review A
  • H Jin · F M Liu · P Xu · J L Xia · M L Zhong · Y Yuan · J W Zhou · Y X Gong · W Wang · S N Zhu
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    ABSTRACT: A consequent tendency toward high-performance quantum information processing is to develop the fully integrated photonic chip. Here, we report the on-chip generation and manipulation of entangled photons based on reconfigurable lithium-niobate waveguide circuits. By introducing a periodically poled structure into the waveguide circuits, two individual photon-pair sources with a controllable electro-optic phase shift are produced within a Hong-Ou-Mandel interferometer, resulting in a deterministically separated identical photon pair. The state is characterized by 92.9±0.9% visibility Hong-Ou-Mandel interference. The photon flux reaches ∼1.4×10^{7} pairs nm^{-1} mW^{-1}. The whole chip is designed to contain nine similar units to produce identical photon pairs spanning the telecom C and L band by the flexible engineering of nonlinearity. Our work presents a scenario for on-chip engineering of different photon sources and paves the way to fully integrated quantum technologies.
    No preview · Article · Sep 2014 · Physical Review Letters
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    S. M. Wang · Q. Q. Cheng · Y. X. Gong · P. Xu · L. Li · T. Li · S. N. Zhu
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    ABSTRACT: It has been proved that surface plasmon polariton (SPP) can well conserve and transmit the quantum nature of entangled photons. Therefore, further utilization and manipulation of such quantum nature of SPP in a plasmonic chip will be the next task for scientists in this field. In quantum logic circuits, the controlled-NOT (CNOT) gate is the key building block. Here, we implement the first plasmonic quantum CNOT gate with several-micrometer footprint by utilizing a single polarization-dependent beam-splitter (PDBS) fabricated on the dielectric-loaded SPP waveguide (DLSPPW). The quantum logic function of the CNOT gate is characterized by the truth table with an average fidelity of. Its entangling ability to transform a separable state into an entangled state is demonstrated with the visibilities of and for non-orthogonal bases. The DLSPPW based CNOT gate is considered to have good integratability and scalability, which will pave a new way for quantum information science.
    Full-text · Article · Aug 2014
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    Q Q Cheng · T Li · L Li · S M Wang · S N Zhu
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    ABSTRACT: A mode division multiplexer (MDM) based on in-plane diffractions is experimentally demonstrated in a polymer-loaded plasmonic planar waveguide. Three guided modes (TM<sub>1</sub>, TE<sub>1</sub>, and TM<sub>2</sub>) were well demultiplexed by a focusing design with a focal length of about 40 μm, which are clearly distinguished by the polarization control. The experimental results well reproduced the theoretical design and calculation. Moreover, the demultiplexed focal spots directly reflect the different modes, by which a mode diagram of the dielectric-loaded planar waveguide was vividly mapped out by varying the polymer layer thickness. In this regard, the proposed device may not only serve as a MDM for the integrated optics but can also provide a new strategy in analyzing the guided modes.
    Full-text · Article · Jul 2014 · Optics Letters
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    L. Chen · P. Xu · Y. F. Bai · X. W. Luo · M. L. Zhong · M. Dai · M. H. Lu · S. N. Zhu
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    ABSTRACT: We experimentally investigated concurrent parametric downconversion processes in a two-dimensional hexagonally poled lithium tantalate crystal. The substantial enhancement of parametric gain was observed when concurrent processes shared a common parametric beam. Both degenerate and nondegenerate concurrent parametric downconversion processes were studied. Analyses of the spatial forms and output angles showed a strong dependence on the working temperature, during which a well-defined beamlike parametric output was observed. Our results will stimulate the design for coherent high-gain generation of multiple parametric beams and also shed light on the compact engineering of path-entanglement with specific spatial forms based on concurrent spontaneous parametric downconversion processes.
    Full-text · Article · Jun 2014 · Optics Express
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    F. Gao · H. Liu · C. Sheng · C. Zhu · S. N. Zhu
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    ABSTRACT: In this work we present a refractive index sensor based on the leaky radiation of a microfiber. The 5.3um diameter microfiber is fabricated by drawing a commercial optical fiber. When the microfiber is immersed into a liquid with larger refractive index than the effective index of fiber mode, the light will leak out through the leaky radiation process. The variation of refractive index of liquid can be monitored by measuring radiation angle of light. The refractive index sensitivity can be over 400 degree/RIU in theory. In the experiment, the variation value 0.001 of refractive index of liquid around this microfiber can be detected through this technique. This work provides a simple and sensitive method for refractive index sensing application.
    Preview · Article · May 2014 · Optics Express
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    L. Li · T. Li · X. M. Tang · S. M. Wang · Q. J. Wang · S. N. Zhu
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    ABSTRACT: Surface plasmon polariton (SPP) as a bounded mode on a metal/dielectric interface intrinsically has a definite transverse magnetic (TM) polarization that usually lacks further manipulations. However, the in-plane longitudinal components of SPP field can produce versatile polarization states when two orthogonal propagating SPP interfere with each other. Here, we demonstrated a plasmonic polarization router by designing appropriate nanohole arrays that can selectively scatter the interfered SPP fields to desired light beams. It is well proved that our device is able to reconfigure a certain input polarization to all kinds of states with respect to a scattered light. Accompanied with a composite phase modulation by diffractions, multiple focusing beams with different polarization states are simultaneously achieved, promising the possibility in polarization multiplexing and related signal processing. Our design offers a new route for achieving full control of the optical polarizations as well as the optical spin-orbital interactions.
    Full-text · Article · May 2014
  • L. Li · T. Li · X. M. Tang · S. M. Wang · Q. J. Wang · S. N. Zhu
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    ABSTRACT: Surface plasmon polariton (SPP) as a bounded mode on a metal/dielectric interface intrinsically has a definite transverse magnetic (TM) polarization that usually lacks further manipulations. However, the in-plane longitudinal components of SPP field can produce versatile polarization states when two orthogonal propagating SPP interfere with each other. Here, we demonstrated a plasmonic polarization router by designing appropriate nanohole arrays that can selectively scatter the interfered SPP fields to desired light beams. It is well proved that our device is able to reconfigure a certain input polarization to all kinds of states with respect to a scattered light. Accompanied with a composite phase modulation by diffractions, multiple focusing beams with different polarization states are simultaneously achieved, promising the possibility in polarization multiplexing and related signal processing. Our design offers a new route for achieving full control of the optical polarizations as well as the optical spin-orbital interactions.
    No preview · Article · Apr 2014
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    H. Jin · F. M. Liu · P. Xu · J. L. Xia · M. L. Zhong · Y. Yuan · Y. X. Gong · W. Wang · S. N. Zhu
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    ABSTRACT: Integrated quantum optics becomes a consequent tendency towards practical quantum information processing. Here, we report the on-chip generation and manipulation of photonic entanglement based on reconfigurable lithium niobate waveguide circuits. By introducing periodically poled structure into the waveguide interferometer, two individual photon-pair sources with controllable phase-shift are produced and cascaded by a quantum interference, resulting in a deterministically separated identical photon pair. The state is characterized by 92.9% visibility Hong-Ou-Mandel interference. Continuous morphing from two-photon separated state to bunched state is further demonstrated by on-chip control of electro-optic phase-shift. The photon flux reaches ~1.4*10^7 pairs nm-1 mW-1. Our work presents a scenario for on-chip engineering of different photon sources and paves a way to the fully integrated quantum technologies.
    Full-text · Article · Apr 2014
  • H Cheng · X D Jiang · X P Hu · M L Zhong · X J Lv · S N Zhu
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    ABSTRACT: We report a diode-pumped intracavity second-harmonic generation mode-locked solid-state Tm:YAP laser operating at 1988 nm using a periodically poled congruent LiNbO<sub>3</sub> as the nonlinear crystal. The threshold of continuous wave mode locking is 11.6 W. The maximum output power is 1.67 W, while the shortest pulse obtained is 4.7 ps at a repetition rate of 97.09 MHz.
    No preview · Article · Apr 2014 · Optics Letters
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    Q. Q. Cheng · T. Li · R. Y. Guo · L. Li · S. M. Wang · S. N. Zhu

    Full-text · Dataset · Mar 2014
  • X. P. Hu · P. Xu · S. N. Zhu
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    ABSTRACT: The quasi-phase-matching (QPM) technique has drawn increasing attention due to its promising applications in areas such as nonlinear frequency conversion for generating new laser light sources. In this paper, we will briefly review the main achievements in this field. We give a brief introduction of the invention of QPM theory, followed by the QPM-material fabrication techniques. When combing QPM with the solid-state laser techniques, various laser light sources, such as single-wavelength visible lasers and ultraviolet lasers, red–green–blue three-fundamental-color lasers, optical parametric oscillators in different temporal scales, and passive mode-locking lasers based on cascaded second-order nonlinearity, have been presented. The QPM technique has been extended to quantum optics recently, and prospects for the studies are bright.
    No preview · Article · Dec 2013 · Photonics Research
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    Chong Sheng · Hui Liu · Yi Wang · S. N. Zhu · D. A. Genov
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    ABSTRACT: One of the most fascinating predictions of the theory of general relativity is the effect of gravitational lensing, the bending of light in close proximity to massive stellar objects. Recently, artificial optical materials have been proposed to study the various aspects of curved spacetimes, including light trapping and Hawking's radiation. However, the development of experimental toy models that simulate gravitational lensing in curved spacetimes remains a challenge, especially for visible light. Here, by utilizing a microstructured optical waveguide around a microsphere, we propose to mimic curved spacetimes caused by gravity, with high precision. We experimentally demonstrate both far-field gravitational lensing effects and the critical phenomenon in close proximity to the photon sphere of astrophysical objects under hydrostatic equilibrium. The proposed microstructured waveguide can be used as an omnidirectional absorber, with potential light harvesting and microcavity applications.
    Full-text · Article · Sep 2013 · Nature Photonics

Publication Stats

3k Citations
655.04 Total Impact Points

Institutions

  • 1994-2016
    • Nanjing University
      • Department of Physics
      Nan-ching, Jiangsu, China
  • 2011
    • Southeast University (China)
      Nan-ching-hsü, Jiangxi Sheng, China
  • 2007
    • University of California, Berkeley
      • Department of Mechanical Engineering
      Berkeley, California, United States
  • 2005
    • Government of the People's Republic of China
      Peping, Beijing, China