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  • 1. Ao, X. Y.
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Negative refraction of left-handed behavior in porous alumina with infiltrated silver at an optical wavelength2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 10Article in journal (Refereed)
  • 2. Ao, X. Y.
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Polarization beam splitters based on a two-dimensional photonic crystal of negative refraction2005In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, no 16, p. 2152-2154Article in journal (Refereed)
  • 3. Ao, X. Y.
    et al.
    He, Sailing
    KTH, Superseded Departments (pre-2005), Electromagnetic Theory.
    Subwavelength focusing and imaging by a multimode optical waveguide2004In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 29, no 24, p. 2864-2866Article in journal (Refereed)
  • 4. Ao, X. Y.
    et al.
    He, Sailing
    Three-dimensional photonic crystal of negative refraction achieved by interference lithography2004In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 29, no 21, p. 2542-2544Article in journal (Refereed)
  • 5.
    Ao, Xianyu
    et al.
    KTH.
    He, Sailing
    KTH, Superseded Departments (pre-2005), Electromagnetic Theory.
    Two-stage design method for realization of photonic bandgap structures with desired symmetries by interference lithography2004In: Optics Express, E-ISSN 1094-4087, Vol. 12, no 6, p. 978-983Article in journal (Refereed)
    Abstract [en]

    Interference lithography for the fabrication of photonic crystals is considered. A two-stage design method for realization of photonic bandgap structures with desired symmetries is developed. An optimal photonic crystal with a large bandgap is searched by adjusting some parameters while keeping some basic symmetry of the unit cell unchanged. A nonlinear programming method is then used to find the optimal electric field vectors of the laser beams and realize the desired interference pattern. The present method is useful for a rational and systematical design of new photonic bandgap structures.

  • 6. Ao, Xianyu
    et al.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Polarization beam splitter based on a two-dimensional photonic crystal of pillar type2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Applied physics letters, Vol. 89, no 17, p. 171115-Article in journal (Refereed)
    Abstract [en]

    Negatively and positively refractive behaviors are achieved in a two-dimensional photonic crystal of pillar type for TE and TM polarizations, respectively, at the same frequency. The photonic crystal is formed by a triangular lattice of silicon pillars of finite height on a silicon substrate. A polarization beam splitter based on such a photonic-crystal slab is demonstrated. Measurements at near infrared wavelengths indicate that two beams of different polarizations can be split with an extinction ratio of over 10 dB in a wide wavelength range.

  • 7. Ao, Xianyu
    et al.
    Tong, Xili
    Kim, Dong Sik
    Zhang, Lianbing
    Knez, Mato
    Mueller, Frank
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Schmidt, Volker
    Black silicon with controllable macropore array for enhanced photoelectrochemical performance2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 11, p. 111901-Article in journal (Refereed)
    Abstract [en]

    Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO2 by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.

  • 8. Ao, Xianyu
    et al.
    Wang, Xuyue
    Yin, Guanbo
    Dang, Kangkang
    Xue, Yali
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang University, China.
    Broadband Metallic Absorber on a Non-Planar Substrate2015In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 11, no 13, p. 1526-1530Article in journal (Refereed)
    Abstract [en]

    Absorbers for visible and near-infrared light are realized by depositing a thin iron layer on arrays of cones which are replicated from a porous template. The replicated conic structure itself is of several micrometers and ineffective at antireflection, but the subsequent deposition of iron on top generates nanometer-size columnar structures, and thus broadband absorption enhancement is achieved.

  • 9.
    Ao, Xianyu
    et al.
    South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangzhou 510006, Guangdong, Peoples R China..
    Xu, Xinan
    South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangzhou 510006, Guangdong, Peoples R China..
    Dong, Jinwu
    South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangzhou 510006, Guangdong, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. South China Normal Univ, South China Acad Adv Optoelect, Ctr Opt & Electromagnet Res, Guangzhou 510006, Guangdong, Peoples R China.;Zhejiang Univ, Natl Engn Res Ctr Opt Instruments, Ctr Opt & Electromagnet Res, JORCEP, Hangzhou 310058, Zhejiang, Peoples R China..
    Unidirectional Enhanced Emission from 2D Monolayer Suspended by Dielectric Pillar Array2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 41, p. 34817-34821Article in journal (Refereed)
    Abstract [en]

    Monolayers of transition metal dichalcogenides show great promise for optoelectronic devices as atomically thin semiconductors. Although dielectric or metal nanostructures have been extensively studied for tailoring and enhancing emission from monolayers, their applications are limited because of the mode concentrating inside the dielectric or the high optical losses in metals, together with the low quantum yield in monolayers. Here, we demonstrate that a metal-backed dielectric pillar array can suspend monolayers to increase the radiative recombination, and simultaneously, create strongly confined band-edge modes on surface directly accessible to monolayers. We observe unidirectional enhanced emission from WSe2 monolayers on polymer pillar array.

  • 10. Bao, Fanglin
    et al.
    Evans, Julian S.
    Fang, Maodong
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang University, China; South China Normal University, China .
    Inhomogeneity-related cutoff dependence of the Casimir energy and stress2016In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 93, no 1, article id 013824Article in journal (Refereed)
    Abstract [en]

    The Casimir stress and energy density are widely used to study the Casimir force, but they diverge in inhomogeneous systems, making the force seem to be infinite as well. Here we characterize the asymptotic behavior of the Casimir stress and energy density in inhomogeneous systems. We show an unambiguous map of all cutoff-dependent terms in the asymptotic expansion to the pressure and the surface tension through the insertion of multiple boundary layers. This result reveals an elegant subtraction to retrieve a finite stress that yields a cutoff-independent force.

  • 11. Bao, Fanglin
    et al.
    Luo, Bin
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    First-order correction to the Casimir force within an inhomogeneous medium2015In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 91, no 6, article id 063810Article in journal (Refereed)
    Abstract [en]

    For the Casimir piston filled with an inhomogeneous medium, we regularized and expressed the Casimir energy with cylinder kernel coefficients by using the first-order perturbation theory. When the refractive index of the medium is smoothly inhomogeneous (i.e., derivatives of all orders exist), a logarithmically cutoff-dependent term and a quadratically cutoff-dependent term in the Casimir energy are found. We show that in the piston model these terms vanish in the force and thus the Casimir force is always cutoff independent, but these terms will remain in the force in the half-space model and must be removed by additional regularizations. We give explicit benchmark solutions to the first-order corrections of both Casimir energy and Casimir force for an exponentially decaying profile. The present method can be extended to other inhomogeneous profiles. Our results should be useful for future relevant calculations and experimental studies.

  • 12.
    Bao, Fanglin
    et al.
    South China Normal Univ, Ctr Opt & Electromagnet Res, Guangdong Prov Key Lab Opt Informat Mat & Technol, South China Acad Adv Optoelect, Guangzhou 510006, Guangdong, Peoples R China..
    Shi, Kezhang
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, State Key Lab Modern Opt Instrumentat, Ctr Opt & Electromagnet Res,JORCEP,Coll Opt Sci &, Hangzhou 310058, Zhejiang, Peoples R China..
    Cao, Guanjun
    South China Normal Univ, Ctr Opt & Electromagnet Res, Guangdong Prov Key Lab Opt Informat Mat & Technol, South China Acad Adv Optoelect, Guangzhou 510006, Guangdong, Peoples R China..
    Evans, Julian S.
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, State Key Lab Modern Opt Instrumentat, Ctr Opt & Electromagnet Res,JORCEP,Coll Opt Sci &, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. South China Normal Univ, Ctr Opt & Electromagnet Res, Guangdong Prov Key Lab Opt Informat Mat & Technol, South China Acad Adv Optoelect, Guangzhou 510006, Guangdong, Peoples R China.;Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, State Key Lab Modern Opt Instrumentat, Ctr Opt & Electromagnet Res,JORCEP,Coll Opt Sci &, Hangzhou 310058, Zhejiang, Peoples R China.
    Inhomogeneity-Induced Casimir Transport of Nanoparticles2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 13, article id 130401Article in journal (Refereed)
    Abstract [en]

    We propose a scheme for transporting nanoparticles immersed in a fluid, relying on quantum vacuum fluctuations. The mechanism lies in the inhomogeneity-induced lateral Casimir force between a nanoparticle and a gradient metasurface and the relaxation of the conventional Dzyaloshinskii-Lifshitz-Pitaevskii constraint, which allows quantum levitation for a broader class of material configurations. The velocity for a nanosphere levitated above a grating is calculated and can be up to a few microns per minute. The Born approximation gives general expressions for the Casimir energy which reveal size-selective transport. For any given metasurface, a certain particle-metasurface separation exists where the transport velocity peaks, forming a "Casimir passage." The sign and strength of the Casimir interactions can be tuned by the shapes of liquid-air menisci, potentially allowing real-time control of an otherwise passive force, and enabling interesting on-off or directional switching of the transport process.

  • 13.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Development of damage and its impact on surface recombination velocities in dry-etched InP-based photonic crystalsManuscript (Other academic)
  • 14.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Accumulated sidewall damage in dry etched photonic crystals2009In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 27, no 4, p. 1969-1975Article in journal (Refereed)
    Abstract [en]

    Evidence for accumulated damage is provided by investigating the effect of etch duration on the carrier lifetime of an InGaAsP quantum well (QW) inside the InP-based photonic crystal (PhC) structures. It is found that once the quantum well is etched through, additional etching reduces the carrier lifetimes from 800 to 70 ps. The surface recombination velocity (SRV) at the exposed hole sidewalls is determined from the measured carrier lifetimes of the PhC fields with different lattice parameters. The observed variation in the SRV with etch duration also confirms the presence of accumulated sidewall damage. It increases from 6x10(3) to 1.2x10(5) cm s(-1) as the etching time increases from 3 to 50 min. A geometric model based on sputtering theory and on the evolution of the hole shape is developed to explain the accumulation of sidewall damage. The model is used to estimate the number of impact events from sputtered species reaching the QW sidewalls, and the variation in the accumulated impact events with etch duration is shown to be qualitatively consistent with the experimental observations. Finally, the results suggest a new method for tailoring the carrier lifetimes in PhC membrane structures.

  • 15.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Evidence for accumulated sidewall damage in dry etched photonic crystals2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118Article in journal (Other academic)
  • 16.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Srinivasan, Anand
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Impact of dry-etching induced damage in InP-based photonic crystals2008In: PHOTONIC CRYSTAL MATERIALS AND DEVICES VIII, 2008, Vol. 6989, p. U9890-U9890Conference paper (Refereed)
    Abstract [en]

    In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl-2 chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO2 mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.

  • 17. Cai, F.
    et al.
    Yu, J.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Vectorial electric field Monte Caro simulations for focused laser beams (800 nm-2220 nm) in a biological sample2013In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 142, p. 667-681Article in journal (Refereed)
    Abstract [en]

    Here we develop a method that combines vectorial electric field Monte Carlo simulation with Huygens-Fresnel principle theory to determine the intensity distribution of a focused laser beam in a biological sample. The proper wavelengths for deep tissue imaging can be determined by utilizing our method. Furthermore, effects of anisotropic factor, scattering and absorption coeffcients on the focal spots are analyzed. Finally, the focal beams formed by objective lenses with different values of numerical aperture are also simulated to study the focal intensity in the biological sample.

  • 18.
    Cai, Fuhong
    et al.
    Hainan Univ, Coll Mech & Elect Engn, Haikou 570228, Hainan, Peoples R China..
    Chen, Jie
    Hainan Univ, Coll Mech & Elect Engn, Haikou 570228, Hainan, Peoples R China..
    Zhou, Chunling
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Lund Univ, Lund, Sweden..
    Zhu, Xuan
    Hainan Univ, Coll Mech & Elect Engn, Haikou 570228, Hainan, Peoples R China..
    He, Sailing
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Lund Univ, Lund, Sweden..
    Exploratory Study on Light-Sheet Based Three-Dimensional Surface Topography2018In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 161, p. 11-18Article in journal (Refereed)
    Abstract [en]

    Light-sheet microscopy has attracted considerable attention because it is a fluorescence imaging technique with rapid optical sectioning capability for transparent samples. In this study, we report a new application based on light-sheet microscopy for exploratory investigation of three-dimensional surface topography of opaque objects. Instead of using inelastic scattering fluorescent signals, our method utilizes the elastic scattering of light from the surface of opaque samples, which are illuminated by a light sheet generated by a cylindrical lens. Through a simple structural modification by removing the fluorescent filter, the orthogonal imaging module can capture the elastically-scattered image. As the opaque object is scanned by a motorized stage, the light-sheet microscope acquires a series of sectional images, which can be stitched into a three-dimensional surface topography image. This method also offers the opportunity to visualize a 3D fingerprint at micron-level resolution. Therefore, this technique may be used in industry and the biomedical field for the measurement of surface microstructure. To our best knowledge, this is the first time a light-sheet microscopy is utilized to perform surface topography measurement.

  • 19. Cai, Fuhong
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Electric field Monte Carlo simulation of focused stimulated emission depletion beam, radially and azimuthally polarized beams for in vivo deep bioimaging2014In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 19, no 1, p. 011022-Article in journal (Refereed)
    Abstract [en]

    An electric field Monte Carlo method is used to study the focal spot of a stimulated emission depletion (STED) beam, radially and azimuthally polarized beams in a turbid medium as a function of the scattering coefficient. To consider the diffraction of light of the wave nature, the wavefront is decomposed into a set of secondary spherical subwaves according to the Huygens principle. From the simulation results, we can find that the STED beam can still form a doughnut focal spot inside the turbid medium. These simulation results are important for the feasibility study of STED microscopy for in vivo deep bioimaging. Similarly, the focal spot for an azimuthally polarized beam can also keep a doughnut spot at the focal plane in a turbid medium.

  • 20. Cai, Fuhong
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Using graphics processing units to accelerate perturbation Monte Carlo simulation in a turbid medium2012In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, no 4, p. 040502-Article in journal (Refereed)
    Abstract [en]

    We report a fast perturbation Monte Carlo (PMC) algorithm accelerated by graphics processing units (CPU). The two-step PMC simulation [Opt. Lett. 36, 2095 (2011)] is performed by storing the seeds instead of the photon's trajectory, and thus the requirement in computer random-access memory (RAM) becomes minimal. The two-step PMC is extremely suitable for implementation onto CPU. In a standard simulation of spatially-resolved photon migration in the turbid media, the acceleration ratio between using GPU and using conventional CPU is about 1000. Furthermore, since in the two-step PMC algorithm one records the effective seeds, which is associated to the photon that reaches a region of interest in this letter, and then re-run the MC simulation based on the recorded effective seeds, radiative transfer equation (RTE) can be solved by two-step PMC not only with an arbitrary change in the absorption coefficient, but also with large change in the scattering coefficient.

  • 21.
    Cai, Fuhong
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Zhejiang Univ. (China) .
    Qian, Jun
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Zhejiang Univ. (China) .
    Jiang, Li
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Zhejiang Univ. (China) .
    He, Sailing
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Zhejiang Univ. (China) .
    Multifunctional optical imaging using dye-coated gold nanorods in a turbid medium2011In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 16, no 1, p. 016002-Article in journal (Refereed)
    Abstract [en]

    We report multifunctional optical imaging using dye-coated gold nanorods. Three types of useful information, namely, Raman, fluorescence signals, and absorption contrast, can be obtained from a phantom experiment. These three kinds of information are detected in a nanoparticle-doped-phantom using diffuse optical imaging. Our novel nanoparticle could be used as a multimodality marker for future bioimaging applications.

  • 22. Cai, Fuhong
    et al.
    Yu, Jiaxin
    Qian, Jun
    Wang, Ye
    Chen, Zhong
    Huang, Jingyun
    Ye, Zhizhen
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Use of tunable second-harmonic signal from KNbO3 nanoneedles to find optimal wavelength for deep-tissue imaging2014In: Laser & Photonics reviews, ISSN 1863-8880, E-ISSN 1863-8899, Vol. 8, no 6, p. 865-874Article in journal (Refereed)
    Abstract [en]

    Nonlinear optical (NLO) responses of perovskite-type nanostructures have a variety of potential applications owing to the highly efficient frequency conversion guaranteed by both the material itself and the nanometer-scale configuration. KNbO3 (KN) nanoneedles have been identified as a promising NLO material because of the superior broadband frequency conversion efficiency, and if incident light is propagating in a direction perpendicular to the axis of a nanoneedle, then the phase-matching constraint can be relaxed. Here, the second-harmonic generation (SHG) and third-harmonic generation (THG) responses of both individual and clustered KN nanoneedles are reported. Based on these results, a novel method is proposed for determining the optimal excitation wavelength for NLO imaging of several biological samples, with KN nanoneedles acting as NLO agents. The method is shown to provide the optical features in the focal plane and a more reliable estimation of the optimal excitation wavelength for deep-tissue imaging.

  • 23. Cai, Tao
    et al.
    Liu, Qingkun
    Shi, Yaocheng
    Chen, Pengxin
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    An efficiently tunable microring resonator using a liquid crystal-cladded polymer waveguide2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 12, p. 121109-Article in journal (Refereed)
    Abstract [en]

    An electrically tunable polymer microring resonator of large tunability and low applied voltage is demonstrated using active liquid crystal (LC) cladding. A large tuning range of 0.73 nm is achieved due to more homogenous LC molecular alignment and enhanced interaction of the light with the LC cladding in the simplified polymer waveguide structure. The operating voltage decreases to 10 V with a threshold of only 3 V by the utilization of interdigital electrodes.

  • 24. Cai, Tingting
    et al.
    Zhu, Huilin
    Xu, Jie
    Wu, Shijing
    Li, Xinge
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Human cortical neural correlates of visual fatigue during binocular depth perception: An fNIRS study2017In: PLOS ONE, E-ISSN 1932-6203, Vol. 12, no 2, article id e0172426Article in journal (Refereed)
    Abstract [en]

    Functional near-infrared spectroscopy (fNIRS) was adopted to investigate the cortical neural correlates of visual fatigue during binocular depth perception for different disparities (from 0.1 degrees to 1.5 degrees). By using a slow event-related paradigm, the oxyhaemoglobin (HbO) responses to fused binocular stimuli presented by the random-dot stereogram (RDS) were recorded over the whole visual dorsal area. To extract from an HbO curve the characteristics that are correlated with subjective experiences of stereopsis and visual fatigue, we proposed a novel method to fit the time-course HbO curve with various response functions which could reflect various processes of binocular depth perception. Our results indicate that the parietal-occipital cortices are spatially correlated with binocular depth perception and that the process of depth perception includes two steps, associated with generating and sustaining stereovision. Visual fatigue is caused mainly by generating stereovision, while the amplitude of the haemodynamic response corresponding to sustaining stereovision is correlated with stereopsis. Combining statistical parameter analysis and the fitted time-course analysis, fNIRS could be a promising method to study visual fatigue and possibly other multi-process neural bases.

  • 25. Cai, Y.
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Propagation of a Laguerre-Gaussian beam through a slightly misaligned paraxial optical system2006In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 84, no 3, p. 493-500Article in journal (Refereed)
  • 26.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Average intensity and spreading of an elliptical Gaussian beam propagating in a turbulent atmosphere2006In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 5, p. 568-570Article in journal (Refereed)
    Abstract [en]

    An analytical formula for the average intensity of an elliptical Gaussian beam (EGB) propagating in a turbulent atmosphere is derived. The spreading properties of an EGB in a turbulent atmosphere are studied. It is found that an EGB will eventually become a circular Gaussian beam in a turbulent atmosphere. This interesting phenomenon is quite different from the propagation of an EGB in free space. The evolution properties are closely related to the parameters of the beam and the turbulent atmosphere

  • 27. Cai, Yangjian
    et al.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Partially coherent flattened Gaussian beam and its paraxial propagation properties2006In: Journal of the Optical Society of America a-Optics Image Science and Vision, ISSN 1084-7529, Vol. 23, no 10, p. 2623-2628Article in journal (Refereed)
  • 28.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 4Article in journal (Refereed)
    Abstract [en]

    Analytical formulas are derived for the propagation of a partially coherent twisted anisotropic Gaussian Schell-model (TAGSM) beam in a turbulent atmosphere. Propagation properties of a TAGSM beam in a turbulent atmosphere are investigated in detail. It is found that a TAGSM beam will become a circular beam in a turbulent atmosphere, and low coherence and larger twist have an effect of anticircularization of the beam spot. The beam spot spreads more rapidly for lower coherence, larger twist, or stronger turbulence.

  • 29.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Propagation of hollow Gaussian beams through apertured paraxial optical systems2006In: Journal of the Optical Society of America a-Optics Image Science and Vision, ISSN 1084-7529, Vol. 23, no 6, p. 1410-1418Article in journal (Refereed)
    Abstract [en]

    On the basis of the generalized Collins formula and the expansion of the hard-aperture function into a finite sum of complex Gaussian functions, an approximate analytical formula for a hollow Gaussian beam propagating through an apertured paraxial stigmatic (ST) ABCD optical system is derived. Some numerical examples are given. Furthermore, by using a tensor method, we derive approximate analytical formulas for a hollow elliptical Gaussian beam propagating through an apertured paraxial general astigmatic ABCD optical system and an apertured paraxial misaligned ST ABCD optical system. Our results provide a convenient way for studying the propagation and transformation of a hollow Gaussian beam and a hollow elliptical Gaussian beam through an apertured general optical system.

  • 30.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Propagation of various dark hollow beams in a turbulent atmosphere2006In: Optics Express, E-ISSN 1094-4087, Vol. 14, no 4, p. 1353-1367Article in journal (Refereed)
    Abstract [en]

    Propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry in a turbulent atmosphere is investigated. Analytical formulas for the average intensity of various DHBs propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral. The intensity and spreading properties of the DHBs in a turbulent atmosphere are studied numerically. It is found that after a long propagation distance a dark hollow beam of circular or non-circular eventually becomes a circular Gaussian beam (without dark hollow) in a turbulent atmosphere, which is much different from its propagation properties in free space. The conversion from a DHB to a circular Gaussian beam becomes quicker and the beam spot in the far field spreads more rapidly for a larger structure constant, a shorter wavelength, a lower beam order and a smaller waist size of the initial beam.

  • 31.
    Cao, Shun
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    Jin, Yi
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    Dong, Hongguang
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Peoples R China..
    Guo, Tingbiao
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    He, Jinlong
    China Jiliang Univ, Coll Modern Sci & Technol, Hangzhou 310018, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Peoples R China..
    Enhancing single photon emission through quasi-bound states in the continuum of monolithic hexagonal boron nitride metasurface2021In: Journal of Physics: Materials, E-ISSN 2515-7639, Vol. 4, no 3, article id 035001Article in journal (Refereed)
    Abstract [en]

    A patterned structure of monolithic hexagonal boron nitride (hBN) on a glass substrate, which can enhance the emission of the embedded single photon emitters (SPEs), is useful for onchip single-photon sources of high-quality. Here, we design and demonstrate a monolithic hBN metasurface with quasi-bound states in the continuum mode at emission wavelength with ultrahigh Q values to enhance fluorescence emission of SPEs in hBN. Because of ultrahigh electric field enhancement inside the proposed hBN metasurface, an ultrahigh Purcell factor (3.3 x 10(4)) is achieved. In addition, the Purcell factor can also be strongly enhanced in most part of the hBN structure, which makes the hBN metasurface suitable for e.g. monolithic quantum photonics.

  • 32.
    Cao, Shun
    et al.
    Centre for Optical and Electromagnetic Research, National Engineering Research Center for Optical Instruments, Zhejiang University, Hangzhou 310058, China.
    Jin, Yi
    Centre for Optical and Electromagnetic Research, National Engineering Research Center for Optical Instruments, Zhejiang University, Hangzhou 310058, China.
    Dong, Hongguang
    Centre for Optical and Electromagnetic Research, National Engineering Research Center for Optical Instruments, Zhejiang University, Hangzhou 310058, China.
    Guo, Tingbiao
    Centre for Optical and Electromagnetic Research, National Engineering Research Center for Optical Instruments, Zhejiang University, Hangzhou 310058, China.
    Liu, Zhenciao
    He, Jinlong
    College of Modern Science and Technology, China Jiliang University, Hangzhou, 310018, China.
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Centre for Optical and Electromagnetic Research, National Engineering Research Center for Optical Instruments, Zhejiang University, Hangzhou 310058, China b Ningbo Research Institute, Zhejiang University, Ningbo 315100, China.
    High-temperature ultra-broad UV–MIR high-efficiency absorber based on double ring-shaped titanium nitride resonators2021In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 485, article id 126730Article in journal (Refereed)
    Abstract [en]

    An ultrabroad absorber based on double-ring-shaped titanium nitride (TiN) nanoresonators, which can work in high temperatures, is proposed and numerically studied. The absorber with some optimal parameters exhibits an averaged absorption of 94.6% in the range of 200–4000 nm (from ultraviolet to mid-infrared) and a band from 200–3518 nm having an absorption > 90%. We have demonstrated in detail the physical mechanisms of the ultra-broad absorption, including the dielectric lossy property of TiN material itself in shorter wavelengths and plasmonic resonances caused by the metallic property of TiN nano-resonators in longer wavelengths. In addition, the absorber shows polarization independent and wide-angle acceptance. Another absorber with double TiN nano-rings of different heights has flatter and higher absorption efficiency (more than 95% absorption) at 200–2860 nm waveband. These properties make the proposed absorbers based on TiN has great potentials in many applications, such as light trapping, photovoltaics, thermal emitters. 

  • 33.
    Cao, Shun
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    Xing, Yuxin
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China.;Zhejiang Univ, Shanghai Inst Adv Study, Shanghai 200135, Peoples R China..
    Sun, Yuwei
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    Liu, Zhenchao
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Peoples R China.;Zhejiang Univ, Shanghai Inst Adv Study, Shanghai 200135, Peoples R China..
    Strong Coupling between a Single Quantum Emitter and a Plasmonic Nanoantenna on a Metallic Film2022In: Nanomaterials, E-ISSN 2079-4991, Vol. 12, no 9, article id 1440Article in journal (Refereed)
    Abstract [en]

    The strong coupling between single quantum emitters and resonant optical micro/nanocavities is beneficial for understanding light and matter interactions. Here, we propose a plasmonic nanoantenna placed on a metal film to achieve an ultra-high electric field enhancement in the nanogap and an ultra-small optical mode volume. The strong coupling between a single quantum dot (QD) and the designed structure is investigated in detail by both numerical simulations and theoretical calculations. When a single QD is inserted into the nanogap of the silver nanoantenna, the scattering spectra show a remarkably large splitting and anticrossing behavior of the vacuum Rabi splitting, which can be achieved in the scattering spectra by optimizing the nanoantenna thickness. Our work shows another way to enhance the light/matter interaction at a single quantum emitter limit, which can be useful for many nanophotonic and quantum applications.

  • 34. Cao, X.
    et al.
    He, Sailing
    An electro-optic modulator based on GeO2-doped silica ridge waveguides with thermal poling2003In: Chinese Physics Letters, ISSN 0256-307X, E-ISSN 1741-3540, Vol. 20, no 7, p. 1081-1083Article in journal (Refereed)
  • 35. Cao, X.
    et al.
    Wang, Z. G.
    He, Sailing
    Xia, Y. X.
    Zhan, L.
    Comparative studies on annealed proton exchange waveguides in Y-cut MgO: LiNbO3 and Z-cut LiNbO32004In: Wuli xuebao, ISSN 1000-3290, Vol. 53, no 11, p. 3786-3793Article in journal (Refereed)
  • 36. Cao, X.
    et al.
    Wang, Z. G.
    He, Sailing
    Zhan, L.
    Xia, Y. X.
    Optical and structural characterization of annealed proton exchange waveguides in Y-cut MgO: LiNbO32005In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 27, no 10, p. 1596-1601Article in journal (Refereed)
  • 37.
    Chen, Biao
    et al.
    Centre for Optical and Electromagnetic Research, Joint Laboratory of Optical Communications, Zhejiang University, Hangzhou 310027, China.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Efficient and fine scheduling algorithm for bandwidth allocation in Ethernet passive optical networks2006In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 12, no 4, p. 653-660Article in journal (Refereed)
    Abstract [en]

    A novel fine scheduling algorithm is introduced for upstream bandwidth allocation in an Ethernet-based passive optical network. This scheduling algorithm consists of an inter optical network unit (ONU) scheduler at the optical line terminal (OLT) and an intra-ONU scheduler at each ONU. In the inter-ONU scheduling, a novel GATE/REPORT approach is introduced to eliminate the unused remainders without transmission delay and maximize the utilization of bandwidth. Our novel intra-ONU scheduler gives fair bandwidth allocation to the queues of different priorities for each user in a hierarchical and decentralized way. Numerical results have shown that our overall scheduling algorithm can fulfill various requirements of delay and throughput for the transmission of multimedia traffic for each end user..

  • 38. Chen, Biao
    et al.
    Guo, Changjian
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Zhang, Linjian
    Jiang, Qiong
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Add/drop multiplexing and TDM signal transmission in an optical CDMA ring network2007In: Journal of Optical Networking, ISSN 1536-5379, Vol. 6, no 8, p. 969-974Article in journal (Refereed)
  • 39. Chen, D.
    et al.
    Fu, H.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Novel microwave photonic filter based on a mode-locked fiber laser2007In: Laser Physics Letters, ISSN 1612-2011, Vol. 4, no 8, p. 597-600Article in journal (Refereed)
  • 40. Chen, D.
    et al.
    Fu, H.
    Liu, W.
    Wei, Y.
    He, Sailing
    Dual-wavelength single-longitudinal-mode erbium-doped fibre laser based on fibre Bragg grating pair and its application in microwave signal generation2008In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 44, no 7, p. 459-460Article in journal (Refereed)
    Abstract [en]

    A simple dual-wavelength single-longitudinal-mode erbium-doped fibre laser is proposed by incorporating a fibre Bragg grating pair, which is used as a Fabry-Perot filter with two ultra-narrow (similar to 0.12 pm) transmission bands. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength spacing of similar to 0.08 nm is achieved at room temperature. By beating the dual-wavelengths at a photodetector, a microwave signal at 9.616 GHz is demonstrated with a frequency stability better than 1 MHz and a spectral width less that 10 kHz.

  • 41. Chen, D. R.
    et al.
    Liu, W. S.
    Jiang, M.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    High-Resolution Strain/Temperature Sensing System Based on a High-Finesse Fiber Cavity and Time-Domain Wavelength Demodulation2009In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 27, no 13, p. 2477-2481Article in journal (Refereed)
    Abstract [en]

    A high-resolution strain/temperature sensing system based on a fiber Bragg grating-Fabry-Perot cavity (FBG-FPC) and a wavelength-swept single-longitudinal-mode laser diode (modulated by a sawtooth signal) is proposed. The high-finesse (similar to 627) FBG-FPC formed by two uniform FBGs of high reflectivity (similar to 99.5%) is used both as a strain/temperature sensor and a FPC with ultranarrow (similar to 0.12 pm) transmission bands. Using a photodetector to detect the transmissive light of the laser diode through the FBG-FPC, wavelength demodulation is achieved by mapping wavelength measurement to time measurement. Both strain sensing and temperature sensing with a resolution of 0.11 mu epsilon and 0.014 degrees C, respectively, have been demonstrated.

  • 42. Chen, D. R.
    et al.
    Yang, T. J.
    Wu, J. J.
    Shen, L. F.
    Liao, K. L.
    He, Sailing
    Band-rejection fiber filter and fiber sensor based on a Bragg fiber of transversal resonant structure2008In: Optics Express, E-ISSN 1094-4087, Vol. 16, no 21, p. 16489-16495Article in journal (Refereed)
    Abstract [en]

    We propose a novel band-rejection fiber filter based on a Bragg fiber of transversal resonant structure, which can also be used as a fiber sensor. Defect layers are introduced in the periodic high/low index structure in the cladding of the Bragg fiber. Coupling between the core mode and the defect mode results in large confinement loss for some resonant wavelengths inside the band gap of the Bragg fiber. A segment of the Bragg fiber of transversal resonant structure can be used as a band-rejection fiber filter, whose characteristics are mainly determined by the defect layer. The loss peak wavelength of the Bragg fiber is dependent on the refractive index and the thickness of the defect layer which indicates its applications of refractive index and strain sensing.

  • 43. Chen, D.
    et al.
    Shu, C.
    He, Sailing
    Multiple fiber Bragg grating interrogation based on a spectrum-limited Fourier domain mode-locking fiber laser2008In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 33, no 13, p. 1395-1397Article in journal (Refereed)
    Abstract [en]

    A novel fiber Bragg grating (FBG) sensing system based on a spectrum-limited Fourier domain mode-locking (SL-FDML) fiber laser is proposed. Multiple FBGs cascaded in a long fiber are utilized as both the sensors in the system and the wavelength-selected components in the SL-FDML fiber laser. Both wavelength-division multiplexing and spatial-division multiplexing techniques are demonstrated for interrogation of multiple FBGs by mapping the wavelength measurement to the time measurement and by adjusting the driving frequency of the SL-FDML fiber laser. The proposed FBG sensing system, employing techniques of the wavelength- and spatial-domain interrogation of multiple FBGs, can be used in remote and quasi-distributed multipoint sensing.

  • 44. Chen, Daru
    et al.
    Qin, Shan
    Gao, Ying
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Wavelength-spacing tunable multi-wavelength fiber lasers based on hybrid gain medium and Mach-Zehnder interferometer2007In: 2007 Pacific Rim Conference on Lasers and Electro-Optics, IEEE , 2007, p. 4391428-Conference paper (Refereed)
    Abstract [en]

    Wavelength-spacing continuously tunable multi-wavelength fiber lasers based on a Mach-Zehnder interferometer comb filter are achieved. Stable multi-wavelength lasing based on hybrid gains of Erbium-doped fiber amplification and fiber Raman amplification (semiconductor optical amplification) is demonstrated.

  • 45. Chen, Daru
    et al.
    Qin, Shan
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Channel-spacing-tunable multi-wavelength fiber ring laser with hybrid Raman and erbium-doped fiber gains2007In: Optics Express, E-ISSN 1094-4087, Vol. 15, no 3, p. 930-935Article in journal (Refereed)
  • 46. Chen, Daru
    et al.
    Qin, Shan
    Shen, Lingfang
    Chi, Hao
    He, Sailing
    An all-fiber multi-wavelength Raman laser based on a PCF Sagnac loop filter2006In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 48, no 12, p. 2416-2418Article in journal (Refereed)
  • 47.
    Chen, Daru
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Qin, Shan
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Yu, Zhangwei
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Tunable and injection-switchable erbium-doped fiber laser of line structure2007In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 49, no 4, p. 765-768Article in journal (Refereed)
    Abstract [en]

    A tunable and injection-switchable erbium-doped fiber (EDF) laser is proposed based on a line structure formed by a fiber Sagnac loop reflector and an fiber Bragg grating (FBG). Wavelength switching is achieved by controlling the power of the tunable injection laser. The self-seeded wavelength corresponding to the Bragg wavelength of the FBG can be tuned by, for example, heating the FBG, and the injection wavelength can be tuned over a wide range of about 50 nm. The characteristics of the wavelength switching for different levels of the EDF pump power and different wavelengths of the injection laser are studied experimentally. The present fiber laser has the advantages of tunability, stability, low amplified spontaneous emission noise, and high injection efficiency when compared with a fiber ring laser. Rapid wavelength switching is expected and the transient switching response of the laser is also studied.

  • 48.
    Chen, Daru
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Yu, Zhangwei
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Qin, S.
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Switchable dual-wavelength Raman erbium-doped fibre laser2006In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 42, no 4, p. 202-204Article in journal (Refereed)
    Abstract [en]

    A fibre Bragg grating feedback fibre laser with both Raman and erbium-doped fibre pumps is proposed. Dual-wavelength switching is achieved by controlling the power of the Raman pump. The characteristics of the dual-wavelength switching are studied experimentally, and the mechanism is explained physically.

  • 49.
    Chen, Daru
    et al.
    Centre for Optical and Electromagnetic Research, Department of Optical Engineering, Zhejiang University.
    Yu, Zhangwei
    Centre for Optical and Electromagnetic Research, Department of Optical Engineering, Zhejiang University.
    Qin, Shan
    Centre for Optical and Electromagnetic Research, Department of Optical Engineering, Zhejiang University.
    He, Sailing
    Centre for Optical and Electromagnetic Research, Department of Optical Engineering, Zhejiang University.
    Some switchable dual-wavelength fibre lasers based on fibre Bragg grating feedback2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6351, p. U864-U872Article in journal (Refereed)
    Abstract [en]

    Two methods to achieve dual-wavelength switching in a fibre laser are proposed and two corresponding switchable dual-wavelength fibre lasers based on fibre Bragg grating (FBG) feedback are demonstrated in this paper. In one proposed fibre laser, both Raman and Erbium-doped fibre (EDF) pumps are employed and the dual-wavelength switching is achieved by controlling the power of the Raman pump. In the other proposed fibre laser, an injection technique is used and the dual-wavelength switching is realized by controlling the power of the injection laser. The detailed behavior of the dual-wavelength switching in the two fibre lasers is experimentally studied and the principle is explained physically.

  • 50.
    Chen, Hongzhi
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Yan, Guofeng
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Forsberg, Erik
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Terahertz polarization splitter based on a dual-elliptical-core polymer fiber2016In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 55, no 23, p. 6236-6242Article in journal (Refereed)
    Abstract [en]

    A terahertz polarization splitter based on a dual-elliptical-core polymer fiber is proposed and theoretically optimized. Dual-elliptical cores with subwavelength-scale diameters are independently suspended within a fiber, which not only support two orthogonal polarization modes, being single-mode guided with low absorption losses, but also allow them to switch from one core to the other, with different coupling lengths. As a consequence, the two polarizations can be easily separated by choosing a suitable transmission length at a desired operation frequency. The transmission modes, coupling lengths for x- and y-polarizations, as well as the performance of the proposed polarization splitter at a center-frequency of 0.6 THz are investigated and numerically analyzed. A 1.43 cm long splitter with an ultralow loss of 0.4 dB, a high extinction ratio better than -10 dB and a bandwidth of 0.02 THz is achieved.

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