科研成果

2013
Zhang, X., Li, Z., Chen, J., Yue, S. & Gong, Q. A dichroic surface-plasmon-polariton splitter based on an asymmetric T-shape nanoslit. OPTICS EXPRESS 21, 14548-14554 (2013).Abstract SCI被引用次数:16.
An asymmetric T-shape nanoslit in a metal film is proposed to act as an efficient dichroic surface-plasmon-polariton (SPP) splitter, which is composed of a single nanoslit in immediate contacting with two nanogrooves with different widths. Simulations show that, due to the interferences of SPPs in the upper part of the asymmetric T-shape nanoslit, the generated SPPs propagating to the left and right directions on the front metal surface can be manipulated nearly independently by altering the right and left groove widths, respectively. Based on such effects, a dichroic SPP splitter is demonstrated and the splitting wavelengths can easily be adjusted. High splitting ratios of 31: 1 and 1: 12 at splitting wavelengths of 680 nm and 884 nm are numerically presented with a device's lateral dimension of only 1200 nm. Further experimental results match the simulations well. (C)2013 Optical Society of America
Chen, J., Li, Z., Xiao, J. & Gong, Q. Efficient All-Optical Molecule-Plasmon Modulation Based on T-shape Single Slit. PLASMONICS 8, 233-237 (2013).Abstract SCI被引用次数:7.
Efficient all-optical molecule-plasmon modulation is experimentally demonstrated by employing a compact T-shape single slit on a metal film coated with an azopolymer film, in which the azobenzene molecules can be reoriented by a pump beam. In the T-shape single slit, the transmission spectra exhibit periodic behaviors and are quite sensitive to variations of the refractive index of the azopolymer in the groove. Under a pump beam, the azobenzene molecules are reoriented, so the SPPs in the groove feel a refractive index quite different from that of the originally isotropic azopolymer with randomly orientations. This leads to a high modulation depth of about 53 % (3.3 dB) and a phase variation of >pi experimentally.
Chen, J., et al. Response Line-Shapes in Compact Coupled Plasmonic Resonator Systems. PLASMONICS 8, 1129-1134 (2013).Abstract SCI被引用次数:15.
A compact plasmonic coupled-resonator system, consisting of a stub resonator and baffles in the metal-insulator-metal waveguide, is numerically investigated with the finite element method. Simulations show that sharp and asymmetric response line-shapes can occur in the system. The asymmetric line-shapes in the transmission spectra depend on the relative positions of the resonant wavelengths between the single-stub resonator and the inner resonator constructed by the baffle and the stub resonator, while the other part of the transmission spectra (except the asymmetric part) maintains the spectral features of the structure constructed by the baffles. An analytic model and a relative phase analysis based on the scattering matrix theory are used to describe and explain this phenomenon. These sharp and asymmetric response line-shapes are important for improving the nano-plasmonic devices' performances.
Chen, J., et al. Coupled-Resonator-Induced Fano Resonances for Plasmonic Sensing with Ultra-High Figure of Merits. PLASMONICS 8, 1627-1631 (2013).Abstract SCI被引用次数:56.
Fano resonances are numerically predicted in an ultracompact plasmonic structure, comprising a metal-isolator-metal (MIM) waveguide side-coupled with two identical stub resonators. This phenomenon can be well explained by the analytic model and the relative phase analysis based on the scattering matrix theory. In sensing applications, the sensitivity of the proposed structure is about 1.1 x 10(3) nm/RIU and its figure of merit is as high as 2 x 10(5) at lambda=980 nm, which is due to the sharp asymmetric Fano line-shape with an ultra-low transmittance at this wavelength. This plasmonic structure with such high figure of merits and footprints of only about 0.2 mu m(2) may find important applications in the on-chip nano-sensors.
2012
Chen, J., et al. Plasmonic Y-splitters of High Wavelength Resolution Based on Strongly Coupled-Resonator Effects. PLASMONICS 7, 441-445 (2012).Abstract SCI被引用次数:34.
Based on the strongly coupled-resonator effects, a high wavelength-resolution plasmonic Y-splitter, consisting of a Y-branch metal-insulator-metal waveguide with a baffle in each channel, is numerically investigated using the finite element method. Due to the coupling of different resonators (with nearly equal bandwidths) in the Y-splitter, sharp and asymmetric transmission spectra occur. This greatly increases the wavelength resolution of the Y-splitter to be Delta lambda a parts per thousand aEuro parts per thousand 15 nm, which is significantly narrower than the bandwidth of the single resonator (Delta lambda (FWHM) a parts per thousand aEuro parts per thousand 110 nm). An analytic model based on the scattering matrix theory is provided to describe and explain this phenomenon.
Plasmon-Induced Transparency in Asymmetric T-Shape Single Slit
Chen, J., Li, Z., Yue, S., Xiao, J. & Gong, Q. Plasmon-Induced Transparency in Asymmetric T-Shape Single Slit. NANO LETTERS 12, 2494-2498 (2012).Abstract SCI被引用次数:97.
By utilizing a dielectric-film-coated asymmetric T-shape single slit, comprising two grooves of slightly detuned widths immediately contacting with a single nanoslit, the plasmon-induced transparency was experimentally demonstrated. Because of the symmetry breaking in the unit-cell structure, the scattered lights from the two grooves with slightly detuned widths interfere destructively, leading to the plasmon-induced transparency. As a result, a response spectrum with nearly the same interference contrast but a much narrower bandwidth emerges in the unit-cell structure with the footprint of only about 0.9 mu m(2), compared with that in the symmetric T-shape single slit. These pronounced features in the structure, such as the increased quality factor, ultracompact size, easy fabrication, and experimental observation, have significant applications in ultracompact plasmonic devices.
Chen, J., et al. Highly efficient nanofocusing based on a T-shape micro-slit surrounded with multi-slits. OPTICS EXPRESS 20, 17734-17740 (2012).Abstract SCI被引用次数:9.
Highly efficient plasmonic nanofocusing is proposed and demonstrated in a T-shape micro-slit surrounded by multi-slits. The nanofocusing phenomenon is achieved based on the multimode interference in the micro-slit, the constructive interference in the T-shape slit, and also the multiple-beam interference of the light radiated from the multi-slits and the transmitted light from the T-shape micro-slit. Because of the large illumination areas of the incident light on the wide slit aperture in the proposed structure, a large amount of light can pass through the wide slit. This leads to a highly efficient nanofocusing. Meanwhile, the wide slit means easy fabrication. In the experiment, the focusing phenomenon in the proposed structure was successfully demonstrated with a scanning near-field optical microscopy (SNOM) technology. (C) 2012 Optical Society of America
Multiple plasmon-induced transparencies in coupled-resonator systems
Chen, J., Wang, C., Zhang, R. & Xiao, J. Multiple plasmon-induced transparencies in coupled-resonator systems. Optics Letters 37, 5133-5135 (2012).Abstract SCI被引用次数:80.
Multiple plasmon-induced transparencies are numerically predicted in an ultracompact plasmonic structure, comprising series of stub resonators side-coupled with a metal-isolator-metal waveguide. Because of the phase-coupled effect, electromagnetically induced transparency (EIT)-like spectral response occurs between two adjacent stub resonators with detuned resonant wavelengths. In this approach, multiple EIT-like spectral responses, with bandwidths of the order of several nanometers, are obtained in the plasmonic structure with a small footprint of about 0.6 mu m(2). An analytic model and the relative phase analysis based on the scattering matrix theory are used to explain this phenomenon. (C) 2012 Optical Society of America
You, Z., Jiang, D., Stamnes, J., Chen, J. & Xiao, J. Characteristics and applications of two-dimensional light scattering by cylindrical tubes based on ray tracing. APPLIED OPTICS 51, 8341-8349 (2012).Abstract SCI被引用次数:2.
The intensity distribution of light scattered by a capillary tube filled with a liquid is studied using geometrical optics or ray tracing. Several intensity step points are found in the scattering pattern due to contributions from different geometrical rays. The scattering angles of these intensity step points vary with the capillary parameters, i.e., with the inner and outer radii of the capillary wall and the refractive indices of the liquid and the wall material. The relations between the scattering angles of the step points and the capillary parameters are analyzed using the reflection law and Snell's law. A method is developed to determine the capillary parameters from measurements of the scattering angles of the step points. An experiment is designed to provide measured data from which the capillary parameters can be obtained by the proposed method. It is shown that this method provides capillary parameters of high precision. (c) 2012 Optical Society of America
Chen, W., JianJun, C., WeiHua, T. & JingHua, X. Ultracompact Refractive Index Sensor Based on Surface-Plasmon-Polariton Interference. CHINESE PHYSICS LETTERS 29, 127304 (2012).Abstract SCI被引用次数:4.
Using an ultracompact groove-slit-groove (GSG) structure, a refractive index sensor with a broadband response is proposed and experimentally demonstrated. Due to the interference of surface plasmon polaritons (SPPs), the transmission spectra in the GSG structure exhibit oscillation behaviors in a broad bandwidth, and they are quite sensitive to the refractive index of the surroundings. Based on the principle, the characteristics of its refractive index sensing are demonstrated experimentally. In the experiment, the structure is illuminated with a bulk light source (not a tightly focused light source) from the back side. This decreases the difficulty of the experimental measurement and can protect strong light sources from damaging the detection samples. Meanwhile, the whole structure of the sensor can be made more ultracompact without considering the influence of the incident waves.
Yue, S., Li, Z., Chen, J. & Gong, Q. Deep subwavelength confinement and giant enhancement of light field by a plasmonic lens integrated with a metal-insulator-metal vertical nanocavity. OPTICS EXPRESS 20, 19060-19066 (2012).Abstract SCI被引用次数:4.
A metal-insulator-metal vertical nanocavity is proposed to be integrated at the center of a plasmonic lens. Utilizing cavity resonance effect, the light intensity at the center of the integrated plasmonic lens gets enhancement up to 5500 times compared to that without the cavity, and the light field is tightly confined into a spot as small as 6.0 x 10(-3)lambda(2)(0). The Purcell factor of the cavity reaches up to 1400, ensuring greatly enhanced light-matter interaction inside the cavity. Moreover, the proposed structure takes advantage of linearly polarized light excitation and easy fabrication. (C) 2012 Optical Society of America
2011
Song, Y., Zhi, L., Jian-Jun, C. & Qi-Huang, G. Dielectric waveguide with deep subwavelength mode confinement based on coupled nanowires. ACTA PHYSICA SINICA 60, 094214 (2011).Abstract SCI被引用次数:1.
Dielectric waveguide with deep subwavelength mode confinement based on coupled semiconductor nanowires is proposed. Through the coupling between two adjacent nanowires with high refractive indexes, light can be efficiently confined in the nano-gap between the nanowires with a low refractive index. Numerical simulations indicate that the effective mode area of such a waveguide can be as small as lambda(2)(0)/200, which is one order of magnitude smaller than that of a single nanowire, and such a mode confinement is comparable to that of hybrid plasmonic waveguide. It is also shown that from the view of real applications, possible existing low refractive index oxidization layers of nanowires, low refractive index substrate and small deviation of nanowire dimensions do not have significant influence on the property of the waveguide. As the propagation length is theoretically infinite for dielectric waveguides, such a coupled nanowire waveguide with deep subwavelength mode confinement may have important applications in future integrated photonic circuits.
Chen, J., Li, Z., Li, J. & Gong, Q. Compact and high-resolution plasmonic wavelength demultiplexers based on Fano interference. OPTICS EXPRESS 19, 9976-9985 (2011).Abstract SCI被引用次数:59.
Using strong couplings of different Fabry-Perot (FP) resonators in metal-insulator-metal waveguides, a compact plasmonic wavelength demultiplexer is numerically demonstrated with high wavelength resolution. In the demultiplexer, it is found that new right-angle resonators emerge with bandwidth narrower than that of the isolated FP resonators. These narrowband right-angle resonators interfere with the broadband FP resonators, resulting in Fano-line shapes in the transmission spectra. Consequently, these sharp and asymmetric Fano-line shapes considerably increase the resolution of wavelength demultiplexing, which is significantly narrower than the full width of the isolated FP resonator. (C) 2011 Optical Society of America
Highly Efficient All-Optical Control of Surface-Plasmon-Polariton Generation Based on a Compact Asymmetric Single Slit
Chen, J., Li, Z., Yue, S. & Gong, Q. Highly Efficient All-Optical Control of Surface-Plasmon-Polariton Generation Based on a Compact Asymmetric Single Slit. Nano Letters 11, 2933-2937 (2011).Abstract SCI被引用次数:40.
By engaging a compact asymmetric single slit coated with a photorefractive polymer, surface-plasmon-polariton (SPP) generation was efficiently controlled by a pump beam. In the structure, the nonlinear light-matter interaction is enhanced because of the cavity effect, which increases the sensitivity of SPPs to the surrounding dielectric. By variation of the real part of the refractive index together with an interferometric configuration, high on/off switching ratios are achieved. Moreover, the SPP generation and modulation processes are integrated in the same asymmetric single slit, which makes the device ultracompact. Experimentally, a high on/off switching ratio of > 20 dB and phase variation of >pi were observed with the device lateral dimension of only about 2 mu m.
Chen, J., et al. Broadband unidirectional generation of surface plasmon polaritons with dielectric-film-coated asymmetric single-slit. OPTICS EXPRESS 19, 26463-26469 (2011).Abstract SCI被引用次数:22.
A dielectric-film-coated asymmetric single nanoslit is proposed to realize broadband unidirectional generation of surface plasmon polaritons (SPPs). Due to the tight field confinements by the dielectric film and the deep groove in the asymmetric single slit, the transmittance of the SPPs in the groove to the left side considerably decreases. This greatly suppresses the left-propagating SPP generation efficiency for a broad bandwidth. Meanwhile, the right-propagating SPP generation efficiency has a flat spectra range because of the low transmittance, too. So the unidirectional SPP generation with bandwidth of > 100 nm around lambda = 750 nm is experimentally achieved for the device lateral dimension of only 865 nm. (C) 2011 Optical Society of America
Yue, S., Li, Z., Chen, J. & Gong, Q. Ultrasmall and ultrafast all-optical modulation based on a plasmonic lens. APPLIED PHYSICS LETTERS 98, 161108 (2011).Abstract SCI被引用次数:8.
By exciting a plasmonic lens with femtosecond laser and utilizing the optical nonlinearity of the gold, an ultrasmall and ultrafast all-optical modulation spot was achieved inside a thin gold film. Near-field pump-probe measurements indicated a modulation spot size of about 600 nm, and a response time of about 1.5 ps. Even smaller spot size of about 300 nm was inferred from numerical simulations, beyond the diffraction limit given an incident wavelength of 1000 nm. Moreover, the optical nonlinearity and the modulation depth were increased by one order of magnitude at the focus compared to that at positions without structures. (C) 2011 American Institute of Physics. [doi:10.1063/1.3581895]
Chen, J., Li, Z., Yue, S. & Gong, Q. Ultracompact surface-plasmon-polariton splitter based on modulations of quasicylindrical waves to the total field. JOURNAL OF APPLIED PHYSICS 109, 073102 (2011).Abstract SCI被引用次数:25.
By coating a metal with a finite-thickness dielectric film, evident differences in the wave-vector magnitude between surface plasmon polaritons (SPPs) and quasicylindrical waves (quasi-CWs) emerge. This brings modulation patterns to the total field on the metal surface near the electromagnetic source. Based on such an effect, an ultracompact SPP splitter with a lateral dimension of only 800 nm is experimentally demonstrated at wavelengths of 740 nm and 832 nm in a dielectric-film-coated asymmetric single nanoslit. These results imply that the additional modulation of quasi-CWs to the total field provide new possibilities for the design of ultracompact plasmonic devices. (C) 2011 American Institute of Physics. [doi:10.1063/1.3564935]
Li, Z., Chen, J., Yue, S. & Gong, Q. Ultracompact Surface Plasmon Polariton Unidirectional Generator Based on Asymmetric Single-Nanoslit. 2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) (2011).Abstract SCI被引用次数:0.
An asymmetric single-nanoslit with lateral dimension of only 370 nm is demonstrated to work as an efficient SPP unidirectional generator at wavelength of 830 nm.
2010
Li, Z., Yue, S., Chen, J. & Gong, Q. Ultrafast spatiotemporal relaxation dynamics of excited electrons in a metal nanostructure detected by femtosecond-SNOM. OPTICS EXPRESS 18, 14232-14237 (2010).Abstract SCI被引用次数:6.
Ultrahigh spatiotemporal resolved pump-probe signal near a gold nano-slit is detected by femtosecond-SNOM. By employing two-color pump-probe configuration and probing at the interband transition wavelength of the gold, signal contributed by surface plasmon polariton is avoided and spatiotemporal evolvement of excited electrons is successfully observed. From the contrast decaying of the periodical distribution of the pump-probe signal, ultrafast diffusion of excited electrons with a time scale of a few hundred femtoseconds is clearly identified. For comparison, such phenomenon cannot be observed by the one-color pump-probe configuration. (C) 2010 Optical Society of America
Efficient unidirectional generation of surface plasmon polaritons with asymmetric single-nanoslit
Chen, J., Li, Z., Yue, S. & Gong, Q. Efficient unidirectional generation of surface plasmon polaritons with asymmetric single-nanoslit. Applied Physics Letters 97, 041113 (2010).Abstract SCI被引用次数:84.
An asymmetric single-nanoslit composed of a conventional nanoslit with a nanogroove next to it in a metallic film is proposed to generate unidirectional surface plasmon polaritons (SPPs) efficiently with back-side illumination. Numerical simulations show that due to the different interference processes of SPPs to opposite directions, efficient unidirectional SPP generation can be achieved. Experimentally, an extinction ratio of about 30:1 for SPPs to opposite directions and a generation efficiency of about 1.8 times that of the symmetrical case are demonstrated at wavelength of 830 nm with the lateral dimension of the asymmetric single-nanoslit of only 370 nm. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3472251]

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