S. N. Zhu

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (232)644.42 Total impact

  • [Show abstract] [Hide abstract]
    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.
    Optics Express 01/2015; 23(2). DOI:10.1364/OE.23.001203 · 3.53 Impact Factor
  • Optics Express 01/2015; 23(12):15098. DOI:10.1364/OE.23.015098 · 3.53 Impact Factor
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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.
    Journal of optics 10/2014; 16(12):125007. DOI:10.1088/2040-8978/16/12/125007 · 2.01 Impact Factor
  • 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.
    Physical Review A 10/2014; 90(4). DOI:10.1103/PhysRevA.90.043842 · 2.99 Impact Factor
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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.
    Physical Review Letters 09/2014; 113(10):103601. DOI:10.1103/PhysRevLett.113.103601 · 7.73 Impact Factor
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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.
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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.
    Optics Letters 07/2014; 39(13):3900-3902. DOI:10.1364/OL.39.003900 · 3.18 Impact Factor
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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.
    Optics Express 06/2014; 22(11). DOI:10.1364/OE.22.013164 · 3.53 Impact Factor
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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.
    Optics Express 05/2014; 22(10). DOI:10.1364/OE.22.012645 · 3.53 Impact Factor
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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.
  • [Show abstract] [Hide abstract]
    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.
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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.
    Optics Letters 04/2014; 39(7):2187-90. DOI:10.1364/OL.39.002187 · 3.18 Impact Factor
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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.
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  • 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.
    Photonics Research 12/2013; 1(4). DOI:10.1364/PRJ.1.000171
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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.
    Nature Photonics 09/2013; 7(11). DOI:10.1038/nphoton.2013.247 · 29.96 Impact Factor
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    L Wang, T Li, R Y Guo, W Xia, X G Xu, S N Zhu
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    ABSTRACT: An electrical pumped microscopic active display with integration of plasmonic polarizer and light-emitting-diode is proposed. Thanks to the strong polarized emission through the rectangular nanoholes, well designed pixels with respect to different polarizations are engineered, which give rise to flexible and controllable active display. As results, polarization multiplexed letter encoding, single and double gray-scale images and animation movies are successfully realized. Our results demonstrate a new strategy in electro-optical integration and indicate potential applications in designing new type of microscopic electro-optical devices.
    Scientific Reports 09/2013; 3:2603. DOI:10.1038/srep02603 · 5.58 Impact Factor
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    ABSTRACT: An experimentally feasible intracavity coupler scheme is proposed to generate bright quadripartite continuous-variable (CV) entanglement by the coupled second-harmonic generation processes. By solving the steady-state equations and calculating the correlation spectra of the four output beams, we show that the four output beams are all entangled with each other according to the sufficient inseparability criterion for multipartite CV entanglement. By utilizing the upconversion process, the generated four entanglement fields have macroscopic intensities as soon as the input fields are turned on.
    Journal of the Optical Society of America B 08/2013; 30(8):2130-. DOI:10.1364/JOSAB.30.002130 · 1.81 Impact Factor
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    ABSTRACT: An integrated realization of photonic entangled states becomes an inevitable tendency toward integrated quantum optics. Here we report the compact engineering of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as a coherent beam splitter to distribute photons into designed spatial modes, producing the heralded single-photon and appealing beamlike two-photon path entanglement. We characterize the path entanglement by implementing quantum spatial beating experiments. Such a multifunctional entangled source can be further extended to the high-dimensional fashion and multiphoton level, which paves a desirable way to engineering miniaturized quantum light sources.
    Physical Review Letters 07/2013; 111(2):023603. DOI:10.1103/PhysRevLett.111.023603 · 7.73 Impact Factor
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    ABSTRACT: We theoretically investigate the long-wavelength optical properties of a plasmonic crystal composed of end-to-end gold nanorod dimers. The strong coupling between incident light and the electron oscillations inside the nanorods gives rise to a plasmon polariton, which can be analogous to the phonon polariton in an ionic crystal. Huang-Kun-like equations are employed to explore the underlying physical mechanism for both symmetrical and asymmetrical geometries. In the long wavelength limit, the macroscopic dielectric response of the proposed structure is deduced analytically. The polariton dispersion curve shows a typical anticrossing profile in the strong coupling regime and adjacent branches are separated by a Rabi splitting. The resultant polaritonic stop band is validated by the numerical simulations.
    AIP Advances 06/2013; 3(6). DOI:10.1063/1.4811854 · 1.59 Impact Factor

Publication Stats

2k Citations
644.42 Total Impact Points

Institutions

  • 1994–2014
    • Nanjing University
      • Department of Physics
      Nan-ching, Jiangsu Sheng, China
  • 2010–2011
    • Southeast University (China)
      Nan-ching-hsü, Jiangxi Sheng, China
  • 2007
    • University of California, Berkeley
      • Department of Mechanical Engineering
      Berkeley, California, United States
  • 2005
    • Academia Sinica
      • Institute of Atomic and Molecular Sciences
      Taipei, Taipei, Taiwan
    • Government of the People's Republic of China
      Peping, Beijing, China
  • 2003
    • Shandong Normal University
      Chi-nan-shih, Shandong Sheng, China