The feature of conduction band （CB） of Tensile-Strained Si（TS-Si） on a relaxed Si1-xGex substrate is systematically investigated, including the number of equivalent CB edge energy extrema, CB energy minima, the po...The feature of conduction band （CB） of Tensile-Strained Si（TS-Si） on a relaxed Si1-xGex substrate is systematically investigated, including the number of equivalent CB edge energy extrema, CB energy minima, the position of the extremal point, and effective mass. Based on an analysis of symmetry under strain, the number of equivalent CB edge energy extrema is presented; Using the K.P method with the help of perturbation theory, dispersion relation near minima of CB bottom energy, derived from the linear deformation potential theory, is determined, from which the parameters, namely, the position of the extremal point, and the longitudinal and transverse masses （m1^＊ and mt^＊）are obtained.展开更多
High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation(SBE). It is found that when the chirp pulse is introduce...High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation(SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved(k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed.展开更多
This paper reports a 6-pole high-temperature superconducting (HTS) microstrip bandpass filter for radio astronomy applications. The filter has a center frequency of 23 GHz and a bandwidth the 2 GHz. We have made many ...This paper reports a 6-pole high-temperature superconducting (HTS) microstrip bandpass filter for radio astronomy applications. The filter has a center frequency of 23 GHz and a bandwidth the 2 GHz. We have made many efforts, such as adopting 0.25-mm-thick substrate, carefully designing the housing box and filter layout, to solve the problems in realizing a K-band planar filter. A special straight-line half-wavelength resonator (center-widen resonator) was also designed to reduce the insertion loss of the filter. The measured results showed a midband insertion loss of 0.11 dB with a ripple of 0.4 dB, and a return loss better than 11.5 dB. Good agreement was obtained between simulated and measured results.展开更多
研制了一款K波段(23~25 GHz)收发一体化多功能芯片。该芯片集成了单刀双掷开关(SPDT)、接收支路低噪声放大器和发射支路高效率功率放大器。为兼顾低噪声和高效率功率特性,对电路的拓扑结构进行了优化选择和设计。在器件特征工作频点,采...研制了一款K波段(23~25 GHz)收发一体化多功能芯片。该芯片集成了单刀双掷开关(SPDT)、接收支路低噪声放大器和发射支路高效率功率放大器。为兼顾低噪声和高效率功率特性,对电路的拓扑结构进行了优化选择和设计。在器件特征工作频点,采用开关模型、噪声模型和非线性大信号模型进行联合仿真设计。测试结果表明,该收发一体多功能芯片在23~25 GHz范围内,接收支路增益23 d B、噪声系数2.5 d B,工作电流仅为12 m A;发射支路增益为30 d B,1 d B压缩点输出功率为18.7 d Bm,功率附加效率达到30%,动态电流仅为70 m A。芯片尺寸小,仅为3.5 mm×2.5 mm。展开更多
The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems.Novel particles,emerged as excitations around exotic band degeneracy points,continue to be reported in real...The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems.Novel particles,emerged as excitations around exotic band degeneracy points,continue to be reported in real materials and artificially engineered systems,but so far,we do not have a complete picture on all possible types of particles that can be achieved.Here,via systematic symmetry analysis and modeling,we accomplish a complete list of all possible particles in time-reversal-invariant systems.This includes both spinful particles such as electron quasiparticles in solids,and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks.We establish detailed correspondence between the particle,the symmetry condition,the effective model,and the topological character.This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.展开更多
设计了一个K波段圆极化器,其工作频率为18至26.5 GHz。K波段包含多条重要的射电天文分子谱线,此波段圆极化器的研制对于天文观测与科学研究有极其重要的意义。圆极化器用于将线极化波转换为圆极化波以便于射电望远镜进行观测。包括其工...设计了一个K波段圆极化器,其工作频率为18至26.5 GHz。K波段包含多条重要的射电天文分子谱线,此波段圆极化器的研制对于天文观测与科学研究有极其重要的意义。圆极化器用于将线极化波转换为圆极化波以便于射电望远镜进行观测。包括其工作原理、设计要点、模型仿真结果等内容。主要着眼于正交模式转换器与移相器这两个圆极化器中的重要器件,通过工作原理分析以及电磁仿真的方法进行器件的具体设计并得出仿真结果。仿真结果各个端口回波损耗均小于-20 d B,且移相器的移相误差小于3.3°。展开更多
文摘The feature of conduction band （CB） of Tensile-Strained Si（TS-Si） on a relaxed Si1-xGex substrate is systematically investigated, including the number of equivalent CB edge energy extrema, CB energy minima, the position of the extremal point, and effective mass. Based on an analysis of symmetry under strain, the number of equivalent CB edge energy extrema is presented; Using the K.P method with the help of perturbation theory, dispersion relation near minima of CB bottom energy, derived from the linear deformation potential theory, is determined, from which the parameters, namely, the position of the extremal point, and the longitudinal and transverse masses （m1^＊ and mt^＊）are obtained.
基金supported by the Natural Science Foundation of Jilin Province (Grant No.20220101010JC)the National Natural Science Foundation of China (Grant No.12074146)。
文摘High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation(SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved(k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed.
基金Supported by the Knowledge Innovative Program of Chinese Academy of Sciences (Grant No. KJCX2-YW-W16)National High-Tech Research and Develop- ment Program of China (Grant No. 2007AA03Z215)
文摘This paper reports a 6-pole high-temperature superconducting (HTS) microstrip bandpass filter for radio astronomy applications. The filter has a center frequency of 23 GHz and a bandwidth the 2 GHz. We have made many efforts, such as adopting 0.25-mm-thick substrate, carefully designing the housing box and filter layout, to solve the problems in realizing a K-band planar filter. A special straight-line half-wavelength resonator (center-widen resonator) was also designed to reduce the insertion loss of the filter. The measured results showed a midband insertion loss of 0.11 dB with a ripple of 0.4 dB, and a return loss better than 11.5 dB. Good agreement was obtained between simulated and measured results.
文摘研制了一款K波段(23~25 GHz)收发一体化多功能芯片。该芯片集成了单刀双掷开关(SPDT)、接收支路低噪声放大器和发射支路高效率功率放大器。为兼顾低噪声和高效率功率特性,对电路的拓扑结构进行了优化选择和设计。在器件特征工作频点,采用开关模型、噪声模型和非线性大信号模型进行联合仿真设计。测试结果表明,该收发一体多功能芯片在23~25 GHz范围内,接收支路增益23 d B、噪声系数2.5 d B,工作电流仅为12 m A;发射支路增益为30 d B,1 d B压缩点输出功率为18.7 d Bm,功率附加效率达到30%,动态电流仅为70 m A。芯片尺寸小,仅为3.5 mm×2.5 mm。
基金supported by the National Key R&D Program of China(2020YFA0308800,2016YFA0300600,and 2017YFB0701600)the National Natural Science Foundation of China(11734003,12061131002,12004028,and 12004035)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB30000000)the China Postdoctoral Science Foundation(2020M670106)the Singapore Ministry of Education AcRF Tier 2(MOE2019-T2-1-001)Beijing Institute of Technology Research Fund Program for Young Schola。
文摘The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems.Novel particles,emerged as excitations around exotic band degeneracy points,continue to be reported in real materials and artificially engineered systems,but so far,we do not have a complete picture on all possible types of particles that can be achieved.Here,via systematic symmetry analysis and modeling,we accomplish a complete list of all possible particles in time-reversal-invariant systems.This includes both spinful particles such as electron quasiparticles in solids,and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks.We establish detailed correspondence between the particle,the symmetry condition,the effective model,and the topological character.This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.
文摘设计了一个K波段圆极化器,其工作频率为18至26.5 GHz。K波段包含多条重要的射电天文分子谱线,此波段圆极化器的研制对于天文观测与科学研究有极其重要的意义。圆极化器用于将线极化波转换为圆极化波以便于射电望远镜进行观测。包括其工作原理、设计要点、模型仿真结果等内容。主要着眼于正交模式转换器与移相器这两个圆极化器中的重要器件,通过工作原理分析以及电磁仿真的方法进行器件的具体设计并得出仿真结果。仿真结果各个端口回波损耗均小于-20 d B,且移相器的移相误差小于3.3°。
