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Optical colorimetric LiTaO_(3)wafers for highprecision lithography on frequency control of SAW devices

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Photonics Research 2024年第2期12卷 341-349页

作者： MING HUI FANG YINONG XIE FANGQI XUE ZHILIN WU JUN SHI SHENG YU YANG YILIN liu ZHIHUANG liu HSIN CHI WANG FAJUN LI qing huo liu JINFENG ZHU School of Electronic Science and Engineering Xiamen UniversityXiamen 361005China Quanzhou San’an Integrated Circuit Co. Ltd.Quanzhou 362300China Eastern Institute of Technology Ningbo 315200China

Surface acoustic wave(SAW)resonators based on lithium tantalate(LT,LiTaO_(3))wafers are crucial elements of mobile communication *** use of intrinsic LT wafers typically brings about low fabrication accuracy of SAW resonators due to strong UV reflection in the lithography *** hinders their resonance frequency control seriously in industrial *** doping and chemical reduction could be applied to decrease the UV reflection of LT wafers for high lithographic ***,conventional methods fail to provide a fast and nondestructive approach to identify the UV performance of standard single-side polished LT wafers for highprecision frequency ***,we propose a convenient on-line sensing scheme based on the colorimetry of reduced Fe-doped LT wafers and build up an automatic testing system for industrial *** levels of Fe doping and chemical reduction are evaluated by the lightness and color difference of LT-based *** correlation between the wafer visible colorimetry and UV reflection is established to refine the lithography process and specifically manipulate the frequency performance of SAW *** study provides a powerful tool for the fabrication control of SAW resonators and will inspire more applications on sophisticated devices of mobile communication.

关键词： lithography doping wafer

Fast Inhomogeneous Plane Wave Algorithm for Homogeneous Dielectric Body of Revolution

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Communications in Computational Physics 2010年第9期8卷 917-932页

作者： Xi Rui Jun Hu qing huo liu School of Electronic Engineering University of Electronic Science and Technology of ChinaChengduSichuan 610054China Department of Electrical and Computer Engineering Duke UniversityDurhamNC 27708USA

To solve the electromagnetic scattering problem for homogeneous dielectric bodies of revolution(BOR),a fast inhomogeneous plane wave algorithm is *** using the Weyl identity and designing a proper integration path,the aggregation and disaggregation factors can be derived *** with the traditional method of moments(MoM),both the memory and CPU time requirements are reduced for large-scale homogeneous dielectric BOR *** results are given to demonstrate the validity and the efficiency of the proposed method.

关键词： Bodies of revolution fast inhomogeneous plane wave algorithm electromagnetic scattering

Multiple resonant excitations of surface plasmons in a graphene stratified slab by Otto configuration and their independent tuning

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Photonics Research 2017年第4期5卷 377-384页

作者： JIN YAO YING CHEN LONGFANG YE NA liu GUOXIONG CAI qing huo liu Institute of Electromagnetics and Acoustics and Department of Electronic Science Xiamen University Department of Electrical and Computer Engineering Duke University

Multiple resonant excitations of surface plasmons in a graphene stratified slab are realized by Otto configuration at terahertz frequencies. The proposed graphene stratified slab consists of alternating dielectric layers and graphene sheets, and is sandwiched between a prism and another semi-infinite medium. Optical response and field distribution are determined by the transfer matrix method with the surface current density boundary *** resonant excitations appear on the angular reflection spectrum, and are analyzed theoretically via the phase-matching condition. Furthermore, the effects of the system parameters are investigated. Among them, the Fermi levels can tune the corresponding resonances independently. The proposed concept can be engineered for promising applications, including angular selective or multiplex filters, multiple channel sensors, and directional delivery of energy.

关键词： mode Multiple resonant excitations of surface plasmons in a graphene stratified slab by Otto configuration and their independent tuning EFB EFA GSP

A Hybrid FETD-FDTD Method with Nonconforming Meshes

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Communications in Computational Physics 2011年第3期9卷 828-842页

作者： Bao Zhu Jiefu Chen Wanxie Zhong qing huo liu State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023P.R.China Department of Electrical and Computer Engineering Duke UniversityDurham NC 27708USA

A quasi non-overlapping hybrid scheme that combines the finite-difference time-domain(FDTD)method and the finite-element time-domain(FETD)method with nonconforming meshes is developed for time-domain solutions of Maxwell’s *** FETD method uses mixed-order basis functions for electric and magnetic fields,while the FDTD method uses the traditional Yee’s grid;the two methods are joined by a buffer zone with the FETD method and the discontinuous Galerkin method is used for the domain decomposition in the FETD *** main features of this technique is that it allows non-conforming meshes and an arbitrary numbers of FETD and FDTD *** hybrid method is completely stable for the time steps up to the stability limit for the FDTD method and FETD *** results demonstrate the validity of this technique.

关键词： Finite-element time-domain finite-difference time-domain discontinuous Galerkin domain decomposition non-conforming mesh

Wideband high-efficient linear polarization rotators

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Frontiers of physics 2018年第5期13卷 97-102页

作者： Zheng-Yong Song Qiong-Qiong Chu Xiao-Peng Shen qing huo liu Institute of Electromagnetics and Acoustics Department of Electronic Science Xiamen University Xiamen 361005 China School of Physical Science and Technology China University of Mining and Technology Xuzhou 221116 China Department of Electrical and Computer Engineering Duke University Durham NC 27708 USA

We demonstrate a wideband polarization rotator with characteristics of high efficiency and large-range incidence angle by using a very simple anisotropic reflective metasurface. The calculated results show that reflection coefficient of cross polarization is larger than 71% over an octave frequency bandwidth from -4.9 GHz to -10.4 GHz. The proposed metasurface can still work very well even at incidence angle of 60°. The experiment at microwave frequencies is carried out and its results agree well with the simulated ones.

关键词： polarization metasurface

Unusual photocarrier and coherent phonon dynamics behaviors of layered PdSe_(2)unveiled by ultrafast spectroscopy of the edge surface

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 143-152页

作者： Tiantian Yun Changfu huo Jinluo Cheng Zhi-Bo liu Xiao-qing Yan Key Laboratory of Weak-Light Nonlinear Photonics Ministry of EducationSchool of PhysicsNankai UniversityTianjin 300071China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China GPL Photonics Laboratory Key Laboratory of Luminescence Science and TechnologyChinese Academy of Sciences&State Key Laboratory of Luminescence Science and ApplicationsChangchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

Layered materials exhibit different electronic and phonon properties along in-plane and out-of-plane directions;existing studies focus on their in-plane behaviors,and the influence of such anisotropies on the dynamics of photocarriers and phonons is ***,we fabricate layered PdSe_(2)crystals with flat edge surfaces and compare the time-resolved ultrafast spectroscopies on their basal and edge *** differences in the transient reflection spectroscopies reveal the inconsistent photocarrier and phonon dynamics behaviors on the two surfaces:the slow hot carrier relaxation process is accelerated and the thermoelasticity-induced longitudinal coherent acoustic phonon oscillation completely vanishes on the edge surface,as compared with the basal *** analysis reveals that the inconsistent hot carrier dynamics originate from the anisotropic properties of low-energy phonons in PdSe_(2),and the absence of phonon oscillation on the edge surface results from the wavevector-limited sensitivity of acoustic B_(1u)***,polarization-dependent spectroscopies indicate the diverse optical anisotropies beyond the in-plane of PdSe_(2).This work provides a new method to explore unique physical properties and modulate the optical anisotropy of layered materials.

关键词： PdSe_(2) ultrafast spectroscopy edge surface carrier dynamics coherent phonon oscillation anisotropy

Tailoring electron vortex beams with customizable intensity patterns by electron diffraction holography

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Opto-Electronic Advances 2024年第2期7卷 14-21页

作者： Pengcheng huo Ruixuan Yu Mingze liu Hui Zhang Yan-qing Lu Ting Xu National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China College of Engineering and Applied Sciences Key Laboratory of Intelligent Optical Sensing and Manipulation and Jiangsu Key Laboratory of Artificial Functional MaterialsNanjing UniversityNanjing 210093China

An electron vortex beam(EVB) carrying orbital angular momentum(OAM) plays a key role in a series of fundamental scientific researches, such as chiral energy-loss spectroscopy and magnetic dichroism spectroscopy. So far, almost all the experimentally created EVBs manifest isotropic doughnut intensity patterns. Here, based on the correlation between local divergence angle of electron beam and phase gradient along azimuthal direction, we show that free electrons can be tailored to EVBs with customizable intensity patterns independent of the carried OAM. As proof-of-concept, by using computer generated hologram and designing phase masks to shape the incident free electrons in the transmission electron microscope, three structured EVBs carrying identical OAM are tailored to exhibit completely different intensity patterns. Furthermore, through the modal decomposition, we quantitatively investigate their OAM spectral distributions and reveal that structured EVBs present a superposition of a series of different eigenstates induced by the locally varied geometries. These results not only generalize the concept of EVB, but also demonstrate an extra highly controllable degree of freedom for electron beam manipulation in addition to OAM.

关键词： electron vortex beam orbital angular momentum diffraction holography

Numerical simulation and dimension reduction analysis of electromagnetic logging while drilling of horizontal wells in complex structures

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Petroleum Science 2020年第3期17卷 645-657页

作者： Zhen-Guan Wu Shao-Gui Deng Xu-Quan He Runren Zhang Yi-Ren Fan Xi-Yong Yuan Yi-Zhi Wu qing huo liu School of Geosciences China University of PetroleumQingdao 266580ShandongChina Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071Shandong.China CNPC Key Laboratory for Well Logging China University of PetroleumQingdao 266580ShandongChina Research Institute of Exploration and Development PetroChina Southwest Oil and Gas Field CompanyChengdu 610041SichuanChina Duke University DurhamNC 27705USA

Electromagnetic logging while drilling(LWD)is one of the key technologies of the geosteering and formation evaluation for high-angle and horizontal *** this paper,we solve the dipole source-generated magnetic/electric fields in 2D formations efficiently by the 2.5D finite diff erence ***,by leveraging the field’s rapid attenuation in spectral domain,we propose truncated Gauss–Hermite quadrature,which is several tens of times faster than traditional inverse fast Fourier *** applying the algorithm to the LWD modeling under complex formations,e.g.,folds,fault and sandstone pinch-outs,we analyze the feasibility of the dimension reduction from 2D to *** the formations with smooth lateral changes,like folds,the simplified 1D model’s results agree well with the true responses,which indicate that the 1D simplification with sliding window is ***,for the formation structures with drastic rock properties changes and sharp boundaries,for instance,faults and sandstone pinch-outs,the simplified 1D model will lead to large errors and,therefore,2.5D algorithms should be applied to ensure the accuracy.

关键词： Complex formation structures Horizontal wells Electromagnetic logging while drilling 2.5D algorithm-Model simplification

The Spectral Integral Method(SIM)for the Scattering from an Arbitrary Number of Circular PEC Cylinders

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Electromagnetic Science 2023年第4期1卷 32-40页

作者： qing huo liu Siwei Wan Chunhui Zhu Eastern Institute of Technology Ningbo 315200China Xiamen University Xiamen 361005China Duke University Durham NC 27708-0291USA

We present an accurate spectral integral method(SIM)for the analyses of scattering from multiple circular perfect electric conductor(PEC)*** solves the coupled surface integral equations by using the Fourier series and addition theorem to decouple the *** SIM has exponential convergence so that the error decreases exponentially with the sample density on the surfaces,and requires only about 2–3 points per wavelength(PPW)to reach engineering accuracy defined as higher than 99%accuracy(or with an error smaller than 1%).Numerical results demonstrate that the SIM is much more accurate and efficient than the method of moments(MoM),and thus can be potentially used as the exact radiation boundary condition in the finite element and spectral element methods.

关键词： Method of moments Multiple cylinders Scattering Spectral integral method