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Kinetin Detection Enhancement Based on Photonic Nanojets and Surface-Enhanced Raman Scattering

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 2021年第4期27卷 1页

作者： Lai, Hsien-Chi Wang, Yu-Jui Dai, Chi-An Hsueh, Chun-Hway Wang, Shu-Jen Li, Jia-Han Natl Taiwan Univ Dept Engn Sci & Ocean Engn Taipei 10617 Taiwan Natl Taiwan Univ Dept Chem Engn Taipei 10617 Taiwan Natl Taiwan Univ Dept Mat Sci & Engn Taipei 10617 Taiwan Natl Taiwan Univ Dept Agron Taipei 10617 Taiwan

Surface-enhanced Raman scattering (SERS) technique can increase the Raman signals of the analytes owing to the electric field enhancements on the nanostructures. The strong light intensity, called photonic nanojet, can be formed at the backlight of the dielectric microstructures. Recently, some researchers have applied the photonic nanojets in SERS. In this paper, a layer of synthesized low-cost polystyrene microspheres with the average of small particle size of 4.26 mu m and high refractive index 1.5875 was prepared by dispersion polymerization method and coating on metal nanopillars SERS substrates using air-water interfacial floating method, and it was applied to improve the Raman signal sensitivity of kinetin (6-furfurylaminopurine) which is one kind of plant growth regulators and can function an effective compound for improving plant stress tolerance. The Raman intensity increased from 841 to 4449 for the Raman shift at 1327 cm(-1), about 5.29 times stronger. The SERS experiments using the kinetin of ultralow concentrations are measured and it shows that femto Molar can be measured. The numerical simulations indicated that the enhancement factor was about 4 times for plane wave illumination and 3.1 times for focused Gaussian beam. It has considerable potential for different analytes in sensing applications.

关键词： Substrates Polymers Raman scattering Photonics Metals Regulators Stress Air-water interfacial floating method dispersion polymerization finite-difference time-domain method kinetin photonic nanojets polystyrene microsphere Raman spectroscopy surface-enhanced Raman scattering

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Chiral modes near exceptional points in symmetry broken H1 photonic crystal cavities

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Physical Review Research 2021年第4期3卷 043096-043096页

作者： C. F. Fong Y. Ota Y. Arakawa S. Iwamoto Y. K. Kato Nanoscale Quantum Photonics Laboratory RIKEN Cluster for Pioneering Research Saitama 351-0198 Japan Quantum Optoelectronics Research Team RIKEN Center for Advanced Photonics Saitama 351-0198 Japan Institute for Nano Quantum Information Electronics The University of Tokyo Tokyo 153-8505 Japan Department of Applied Physics and Physico-Informatics Keio University Kanagawa 223-8522 Japan Institute of Industrial Science The University of Tokyo Tokyo 153-8505 Japan Research Center for Advanced Science and Technology The University of Tokyo Tokyo 153-0041 Japan

The H1 photonic crystal cavity supports two degenerate dipole modes of orthogonal linear polarization which could give rise to circularly polarized fields when driven with a π/2 phase difference. However, fabrication errors tend to break the symmetry of the cavity, which lifts the degeneracy of the modes, rendering the cavity unsuitable for supporting circular polarization. We demonstrate numerically a scheme that induces chirality in the cavity modes, thereby achieving a cavity that supports intrinsic circular polarization. By selectively modifying two air holes around the cavity, the dipole modes could interact via asymmetric coherent backscattering, which is a non-Hermitian process. With suitable air hole parameters, the cavity modes approach the exceptional point, coalescing in frequencies and linewidths as well as giving rise to significant circular polarization close to unity. The handedness of the chirality can be selected depending on the choice of the modified air holes. Our results highlight the prospect of using the H1 photonic crystal cavity for chiral light-matter coupling in applications such as valleytronics, spin-photon interfaces, and the generation of single photons with well-defined spins.

关键词： Nanophotonics Photonic crystals Polarization of light Quantum cavities finite-difference time-domain method

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Ultrastrong coupling between THz phonons and photons caused by an enhanced vacuum electric field

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Physical Review Research 2021年第3期3卷 L032021-L032021页

作者： Zhenya Zhang Hideki Hirori Fumiya Sekiguchi Ai Shimazaki Yasuko Iwasaki Tomoya Nakamura Atsushi Wakamiya Yoshihiko Kanemitsu Institute for Chemical Research Kyoto University Uji Kyoto 611-0011 Japan

Ultrastrong coupling (USC) between phonons and vacuum photons can result in fascinating quantum phenomena, though it is difficult to achieve due to the small dipole moments of phonons in solids. Here, we investigate the vacuum Rabi splitting by coupling phonons in perovskite CH3NH3PbI3 films with photons in split ring resonators. As the gap size of the resonator decreases, the coupling strength η increases due to the enhanced vacuum field in the gap, reaching the USC regime (η∼0.24) at a gap size of 100 nm. Our results show that nanoresonators are an excellent platform for studies of vacuum-dressed phonon properties.

关键词： Cavity quantum electrodynamics Light-matter interaction Optical phonons Phonon polariton Perovskites Semiconductors Split-ring resonators finite-difference time-domain method Terahertz time-domain spectroscopy

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Waveguide integrated GaN distributed Bragg reflector cavity using low-cost nanolithography

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MICRO & NANO LETTERS 2019年第13期14卷 1322-1327页

作者： Jia, Simeng Le Boulbar, Emmanuel Balram, Krishna C. Pugh, Jon R. Wang, Tao Allsopp, Duncan W. E. Shields, Philip A. Cryan, Martin J. Univ Bristol Dept Elect & Elect Engn Bristol BS8 1UB Avon England Univ Bath Dept Elect & Elect Engn Bath BA2 7AY Avon England Univ Sheffield Dept Elect & Elect Engn Sheffield S1 4DE S Yorkshire England

This work presents the design, fabrication and measurement of gallium nitride (GaN) distributed Bragg reflector cavities integrated with input and output grating couplers. The devices are fabricated using a new, low-cost nanolithography technique: displacement Talbot lithography combined with direct laser writing lithography. The finite-difference time-domain method has been used to design all the components and measured and modelled results show good agreement. Such devices have applications in GaN integrated photonics and biosensing.

关键词： integrated optics diffraction gratings optical couplers III-V semiconductors gallium compounds nanolithography photolithography optical waveguides finite difference time-domain analysis distributed Bragg reflectors optical fabrication wide band gap semiconductors optical design techniques Bragg reflector cavity gallium nitride distributed Bragg reflector cavities output grating couplers low-cost nanolithography technique displacement Talbot lithography direct laser writing lithography finite-difference time-domain method biosensing waveguide integrated GaN distributed Bragg reflector cavity input grating couplers GaN integrated photonics GaN

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Toward Information Transfer Around a Concave Corner by a Surface-Plasmon-Polariton Wave

IEEE PHOTONICS JOURNAL

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IEEE PHOTONICS JOURNAL 2019年第1期11卷 1-12页

作者： Agrahari, Rajan Lakhtakia, Akhlesh Jain, Pradip K. Indian Inst Technol BHU Mat Architecture Ctr Varanasi 221005 Uttar Pradesh India Indian Inst Technol BHU Dept Elect Engn Varanasi 221005 Uttar Pradesh India Penn State Univ Dept Engn Sci & Mech University Pk PA 16802 USA Natl Inst Technol Dept Elect & Commun Engn Patna 800005 Bihar India

As optical interconnects employing surface-plasmon-polariton (SPP) waves are expected to enable faster communication in integrated circuits, the time-domain Maxwell equations were solved using the finite-difference time-domain method to investigate the transfer of information via a pulse-modulated carrier SPP wave around a concave corner formed by two planar metal/air interfaces. The signal is launched along the first metal/air interface and received along the second metal/air interface. The corner angle affects the intensity and the duration of the received signal, but its shape is largely independent of the corner angle of the corner. Accordingly, the signal received around the concave corner is strongly and positively correlated with the transmitted signal, a promising result for SPP-wave-based optical interconnects. The energy of the received signal varies with the frequency of the carrier SPP wave. The received signal is better correlated with the transmitted signal when the carrier frequency is higher for a fixed value of the corner angle.

关键词： Plasmonic communication surface-plasmon-polariton wave finite-difference time-domain method photonics

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Plasmonic nano bow-tie arrays with enhanced LSPR refractive index sensing

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MICRO & NANO LETTERS 2019年第5期14卷 566-571页

作者： Khoshdel, Vahid Shokooh-Saremi, Mehrdad Ferdowsi Univ Mashhad Dept Elect Engn Mashhad *** Razavi Khorasan Iran

In this work, the performance of the nano bow-tie arrays for biosensing applications has been investigated. Since the geometrical parameters of the device such as the bow-tie length and gap size have major effects on the system's optical response, a parametric study based on finite-difference time-domain (FDTD) method has been conducted. In order to enhance the sensitivity, two bow-tie shaped nanoparticles in the form of 2 x 1 and 2 x 2 arrays have been developed. In the case of TM polarisation, a sensitivity up to 923 nm/RIU with a figure of merit (FOM) of 5.5 has been obtained for 2 x 2 nano bow-tie array. Moreover, the performance of the proposed nanoparticles for TE polarisation has been evaluated and a FOM exceeding 15.9 has been achieved for single nano bow-tie. According to this study, the proposed nano bow-tie structures have a great potential for sensing and detection applications.

关键词： nanosensors surface plasmon resonance refractive index optical sensors refractive index measurement nanoparticles finite difference time-domain analysis optical arrays nanophotonics sensor arrays light polarisation plasmonic nanobow-tie arrays enhanced LSPR refractive index sensing biosensing applications bow-tie length gap size finite-difference time-domain method bow-tie shaped nanoparticles 2 x 2 nanobow-tie array detection applications geometrical parameters TM polarisation

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On the representation of thin wires inside lossy dielectric materials for FDTD-based LEMP simulations

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IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 2019年第9期14卷 1314-1322页

作者： Tatematsu, Akiyoshi Rachidi, Farhad Rubinstein, Marcos Cent Res Inst Elect Power Ind Elect Power Engn Res Lab 2-6-1 Nagasaka Yokosuka Kanagawa 2400196 Japan Swiss Fed Inst Technol EMC Lab Elect Engn Inst CH-1015 Lausanne Switzerland Univ Appl Sci Western Switzerland Inst Informat & Commun Technol CH-1401 Yverdon Switzerland

The finite-difference time-domain method is one of the most widely used numerical electromagnetic computation techniques, and it has become an effective tool for analyzing electromagnetic transient phenomena in three-dimensional structures and grounding systems. However, the available approaches for representing thin wires apply only to bare conductors such as overhead power lines and earth electrodes. In this work, we demonstrate the applicability of thin-wire representation techniques to wires surrounded by both lossy and lossless media, such as reinforcing bars inside lossy concrete. The validated technique is then illustrated through the study of a reinforced-concrete building struck by lightning to evaluate the effect of concrete on the penetration of lightning electromagnetic pulses inside the building. (c) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

关键词： building finite-difference time-domain method lighting electromagnetic pulse reinforced concrete

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Unconditionally stable five-step LOD-FDTD method in plasma medium

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INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 2019年第2期32卷 e2522-e2522页

作者： Feng, Xuejian Deng, Haochuan Wei, Xiao Yin, Hongcheng Yang, Lixia Commun Univ China Dept Informat Engn Beijing 100024 Peoples R China Sci & Technol Electromagnet Scattering Lab Beijing Peoples R China Jiangsu Univ Dept Commun Engn Zhenjiang Peoples R China

A three-dimensional unconditionally stable five-step locally one-dimensional finite-difference time-domain (LOD-FDTD) method for anisotropic magnetized plasma medium is presented. Firstly, we search for a diagonal matrix to transform Maxwell coefficient matrix of plasma into skew symmetric matrix which is beneficial to analyze the properties of the proposed algorithm. Then, the detailed formula derivation and numerical stability analysis is presented. At last, the resonance frequency of a microwave cavity partially filled with a plasma slab and the rotation angle of an infinite plasma slab are simulated to verify the accuracy and stability of the proposed method. The effectiveness of the proposed method is further demonstrated by comparing with the three-step LOD-FDTD method.

关键词： finite-difference time-domain method locally one-dimensional magnetized plasma cavity

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Hourglass nonlinear photonic crystal cavity for ultra-fast all-optical switching

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OPTIK 2019年 180卷 858-865页

作者： Rebhi, Sana Najjar, Monia Univ Tunis El Manor Natl Engn Sch Tunis Commun Syst LR 99 ES21 LR SysCom ENIT Tunis 1002 Tunisia Univ Tunis El Manor Higher Inst Comp Sci Ariana 2080 Tunisia

In this paper, a new design of an ultra fast all optical switch based on a new photonic crystal cavity combined with Kerr effect is proposed and its performance is studied. Numerical methods such as plane wave expansion (PWE) and finite difference time domain (FDTD) are used to perform simulations and study the optical properties of the proposed switch. Switching from ON to OFF status occurred when the resonant wavelength is shifted due to Kerr effect. The simulation results show that switch has a high-speed response of similar to 15 ps and since it has an ultra-small size of 273.24 mu m(2), it has a potential to be used in integrated optical-circuits.

关键词： All-optical switching Photonic crystal cavity finite-difference time-domain method Optical Kerr effect

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Reflectivity of three-dimensional GaAs photonic band-gap crystals of finite thickness

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Physical Review B 2020年第23期101卷 235303-235303页

作者： Takeyoshi Tajiri Shun Takahashi Cornelis A. M. Harteveld Yasuhiko Arakawa Satoshi Iwamoto Willem L. Vos Institute of Industrial Science The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo 153-8505 Japan Department of Computer and Network Engineering University of Electro-Communications 1-5-1 Chofugaoka Chofu Tokyo 182-8585 Japan Kyoto Institute of Technology Matsugasaki Sakyo-ku Kyoto 606-8585 Japan Complex Photonic Systems (COPS) MESA+ Institute for Nanotechnology University of Twente P.O. Box 217 7500 AE Enschede The Netherlands Institute for Nano Quantum Information Electronics The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo 153-8505 Japan Research Center for Advanced Science and Technology Institute of Industrial Science The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo 153-0041 Japan

We study the optical reflectivity of real three-dimensional (3D) photonic band-gap crystals with increasing thickness. The crystals consist of GaAs plates with nanorod arrays that are assembled by an advanced stacking method into high-quality 3D woodpile structures. We observe intense and broad reflectivity peaks with stop bands that correspond to a broad gap in the photonic band structures. The maximum reflectivity quickly reaches high values, even for a few crystal layers. Remarkably, the bandwidth of the stop bands hardly decreases with increasing crystal thickness, in good agreement with finite-difference time domain (FDTD) simulations. This behavior differs remarkably from the large changes observed earlier in weakly interacting 3D photonic crystals. The nearly constant bandwidth and high reflectivity are rationalized by multiple Bragg interference that occurs in strongly interacting photonic band-gap crystals, whereby the incident light scatters from multiple reciprocal lattice vectors simultaneously, in particular, from oblique ones that are parallel to a longer crystal dimension and thus experience hardly any finite-size effects. Our insights have favorable consequences for the application of 3D photonic band-gap crystals, notably since even thin structures reveal the full band-gap functionality, including devices that shield quantum bits from vacuum fluctuations.

关键词： Local density of states Nanophotonics Photonic crystals finite-difference time-domain method Reflectivity

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