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Chinese Optics Letters 2007年第12期5卷 709-711页

作者： Weibin Chen Qiwen Zhan Electro-Optics Graduate Program University of Dayton 300 College Park Dayton Ohio 45469-0245 USA

Plasmonic field enhancement in a fully coated dielectric near field scanning optical microscope （NSOM） probe under radial polarization illumination is analyzed using an axially symmetric three-dimensional （3D） finite element method （FEM） model. The enhancement factor strongly depends on the illumination spot size, taper angle of the probe, and the metal film thickness. The tolerance of the alignment angle is investigated. Probe designs with different metal coatings and their enhancement performance are studied as well. The nanometric spot size at the tip apex and high field enhancement of the apertureless NSOM

关键词： field enhancement Finite element method Metrology Near field scanning optical microscopy Polarization Rayleigh scattering

An on-Si directional second harmonic generation amplifier for MoS2/WS2 heterostructure

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Nano Research 2023年第3期16卷 4061-4066页

作者： Jiaxing Du Jianwei Shi Chun Li Qiuyu Shang Xinfeng Liu Yuan Huang Qing Zhang School of Materials Science and Engineering Peking UniversityBeijing 100871China CAS Key Laboratory of Standardization and Measurement for Nanotechnology CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

Transition metal dichalcogenides(TMD)heterostructure is widely applied for second harmonic generation(SHG)and holds great promises for laser source,nonlinear switch,and optical logic gate.However,for atomically thin TMD heterostructures,low SHG conversion efficiency would occur due to reduction of light-matter interaction length and lack of phase matching.Herein,we demonstrated a facile directional SHG amplifier formed by MoS2/WS2 monolayer heterostructures suspended on a holey SiO_(2)/Si substrate.The SHG enhancement factor reaches more than two orders of magnitude in a wide spectral range from 355 to 470 nm,and the radiation angle is reduced from 38°to 19°indicating higher coherence and better emission directionality.The giant SHG enhancement and directional emission are attributed to the great excitation and emission field concentration induced by a self-formed vertical Fabry-Pérot microcavity.Our discovery gives helpful insights for the development of two-dimensional(2D)nonlinear optical devices.

关键词： two-dimensional(2D)materials transition metal dichalcogenides heterostructure second harmonic generation field enhancement optical microcavity

Extra-narrowband metallic filters with an ultrathin single-layer metallic grating

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Chinese Physics B 2020年第6期29卷 242-248页

作者：王然龚旗煌陈建军 State Key Laboratory for Mesoscopic Physics School of PhysicsPeking UniversityBeijing 100871China Microelectronics Instruments and Equipments R&D Center Institude of Microelectronics of Chinese Academy of SciencesBeijing 100029China Nano-optoelectronics Frontier Center of Ministry of Education(NFC-MOE)&Collaborative Innovation Center of Quantum Matter Peking UniversityBeijing 100871China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Narrowband and high-transmission optical filters are extensively used in color display technology, optical information processing, and high-sensitive sensing. Because of large ohmic losses in metallic nanostructures, metallic filters usually exhibit low transmittances and broad bandwidths. By employing both strong field enhancements in metallic nano-slits and the Wood’s anomaly in a periodic metallic grating, an extra-narrowband and high-transmission metallic filter is numerically predicted in an ultrathin single-layer metallic grating. Simulation results show that the Wood’s anomaly in the ultrathin(thickness H = 60 nm) single-layer metallic grating results in large field enhancements in the substrate and low losses in the metallic grating. As a result, the transmission bandwidth(transmittance T > 60%) at λ = 1200 nm is as small as △λFWHM=1.6 nm, which is smaller than 4% of that in the previous thin dielectric and metallic filters. The corresponding quality factor is as high as Q = λ/△λFWHM= 750, which is 40 times greater than that in the previous reports. Moreover, the thickness of our metallic filter(H = 60 nm) is smaller than 40% of that in the previous reports, and its maximum transmittance can reach up to 80%. In experiments, a narrowband metallic filter with a bandwidth of about △λFWHM = 10 nm, which is smaller than 25% of that in the previous metallic filters, is demonstrated.

关键词： metallic filter extra-narrowband field enhancement Wood’s anomaly

Strong guiding of light in hollow nanowire structures

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Chinese Optics Letters 2007年第9期5卷 543-545页

作者： Liang Chen James De Leon Xiaomin Jin Nano Photonics Inc. 21G Olympia Ave. Suite 50 Woburn MA 01801 USA ElectricaJ Engineering Department California Polytechnic State University San Luis Obispo CA 93407 USA

We have theoretically investigated the guiding mode patterns of hollow nanowires. Two types of nanowires, round shape and hexagonal shape, are examined with different combination of outer and inner radii. Because of electric field discontinuity at hollow interfaces and evanescent modes overlap in low refractive index region, strong light guiding and confinement are achieved in both hollow wire structures.

关键词： Electric fields field enhancement Nanowires Refractive index Slot waveguides Waveguides

Fano-like resonance characteristics of asymmetric Fe_2O_3@Au core/shell nanorice dimer

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Chinese Physics B 2014年第8期23卷 474-480页

作者：王彬兵周骏张昊鹏陈金平 Institute of Photonics Faculty of Science Ningbo University

A geometrical configuration of Fe2O3/Au core-shell nanorice dimer is proposed and its multipolar plasmon Fano- like resonance characteristics are theoretically investigated by generalizing the plasmon hybridization model of individual nanorice to the bright and dark modes of the nanorice dimer. Under the irradiation of polarization light, the extinction spectra of the nanorice dimer are numerically simulated by using the finite element method （FEM）. Our studies show that the Fano-like resonance of the nanorice dimer results in an asymmetric line shape of the Fano dip in the extinction spectrum which can be controlled by varying the structure parameters of the nanorice dimer. Meanwhile, there is a giant field enhancement at the gap between the two nanorices on account of the plasmonic coupling in the nanorice dimer. The aforementioned two characteristics of the nanorice dimer are useful for plasmon-induced transparency and localized surface plasmon resonance sensors.

关键词： localized surface plasmon resonance field enhancement nanorice plasmon hybridization