We report the design and simulation of a dual-band perfect terahertz absorber which is composed of an electric Split-Resonance-Ring(eSRR) layer, polyimide spacer and a metal plate layer. The absorber has two near-unit...We report the design and simulation of a dual-band perfect terahertz absorber which is composed of an electric Split-Resonance-Ring(eSRR) layer, polyimide spacer and a metal plate layer. The absorber has two near-unity absorptions near 0.502 THz and 0.942 THz and both are related to the LC resonance of the eSRR. The results show that the designed terahertz absorber is an excellent electromagnetic wave concentrator. The electromagnetic waves are firstly converged into the spacer and the eSRR layer and are then significantly absorbed.展开更多
As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum we...As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.展开更多
A novel dual-band antenna is proposed for mitigating the multi-path interference in the global navigation satellite system（GNSS） applications. The radiation patches consist of a shortedannular-ring reduced-surface-w...A novel dual-band antenna is proposed for mitigating the multi-path interference in the global navigation satellite system（GNSS） applications. The radiation patches consist of a shortedannular-ring reduced-surface-wave（SAR-RSW） element and an inverted-shorted-annular-ring reduced-surface-wave（ISAR-RSW）element. One key feature of the design is the proximity-coupled probe feeds to increase impedance bandwidth. The other is the defected ground structure band rejection filters to suppress the interaction effect between the SAR-RSW and the ISAR-RSW elements. In addition, trans-directional couplers are used to obtain tight coupling. Measurement results indicate that the antenna has a larger than 10 d B return loss bandwidth and a less than 3 d B axial-ratio（AR） bandwidth in the range of（1.164 – 1.255） GHz and（1.552 – 1.610） GHz. The gain of the passive antenna in the whole operating band is more than 7 d Bi.展开更多
目前以航空航天为代表的极端环境领域对板结构的静态和动态力学性质都提出了更高的要求。在保证结构承载能力的同时,还需要实现轻质化以及使其具有多频带减隔振功能。针对上述要求,设计了一种拉扭耦合超结构板,利用由两个自由度耦合谐...目前以航空航天为代表的极端环境领域对板结构的静态和动态力学性质都提出了更高的要求。在保证结构承载能力的同时,还需要实现轻质化以及使其具有多频带减隔振功能。针对上述要求,设计了一种拉扭耦合超结构板,利用由两个自由度耦合谐振产生的两个低频弯曲波带隙,实现超结构板的低频双频带减振。首先提出一种具有拉扭双自由度的单胞等效模型,并在此基础上利用平面波展开(Plane Wave Expansion,PWE)法进行超结构板带隙特性的计算,最后通过有限元分析(Finite Element Analysis,FEA)验证了带隙计算方法的正确性。研究发现,相比于拉压平动单自由度谐振子,拉扭耦合双自由度谐振子会在板结构中打开一个新的弯曲波带隙。进一步分析归一化等效刚度系数对两个带隙位置和带宽的影响。最后,利用有限元方法计算10'5阵列超结构板的振动传递率,得出的振动衰减区域与由理论计算所得的带隙位置一致。有关结论可为轻质超结构板的多频带减振设计提供参考。展开更多
基金partly supported by National Basic Research Program of China（973 ）（ No. 2007CB310407 ） National Nature Science Foundation of China（ No. 60721001 and No. 60801023 ） International S＆T Cooperation Program of China（ No. 2006DFA53410, No. 2007DFRI0250）.
文摘We report the design and simulation of a dual-band perfect terahertz absorber which is composed of an electric Split-Resonance-Ring(eSRR) layer, polyimide spacer and a metal plate layer. The absorber has two near-unity absorptions near 0.502 THz and 0.942 THz and both are related to the LC resonance of the eSRR. The results show that the designed terahertz absorber is an excellent electromagnetic wave concentrator. The electromagnetic waves are firstly converged into the spacer and the eSRR layer and are then significantly absorbed.
文摘As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.
基金supported by the National Natural Science Foundation of China(61071044)the Traffic Applied Basic Research Project of the Ministry of Transport of China(2010-329-225-030)+2 种基金the Doctor Startup Foundation of Liaoning Province(20141103)the Scientific Research Project of the Department of Education of Liaoning Province(L2013196)the Fundamental Research Funds for the Central Universities(2014YB05)
文摘A novel dual-band antenna is proposed for mitigating the multi-path interference in the global navigation satellite system（GNSS） applications. The radiation patches consist of a shortedannular-ring reduced-surface-wave（SAR-RSW） element and an inverted-shorted-annular-ring reduced-surface-wave（ISAR-RSW）element. One key feature of the design is the proximity-coupled probe feeds to increase impedance bandwidth. The other is the defected ground structure band rejection filters to suppress the interaction effect between the SAR-RSW and the ISAR-RSW elements. In addition, trans-directional couplers are used to obtain tight coupling. Measurement results indicate that the antenna has a larger than 10 d B return loss bandwidth and a less than 3 d B axial-ratio（AR） bandwidth in the range of（1.164 – 1.255） GHz and（1.552 – 1.610） GHz. The gain of the passive antenna in the whole operating band is more than 7 d Bi.
文摘目前以航空航天为代表的极端环境领域对板结构的静态和动态力学性质都提出了更高的要求。在保证结构承载能力的同时,还需要实现轻质化以及使其具有多频带减隔振功能。针对上述要求,设计了一种拉扭耦合超结构板,利用由两个自由度耦合谐振产生的两个低频弯曲波带隙,实现超结构板的低频双频带减振。首先提出一种具有拉扭双自由度的单胞等效模型,并在此基础上利用平面波展开(Plane Wave Expansion,PWE)法进行超结构板带隙特性的计算,最后通过有限元分析(Finite Element Analysis,FEA)验证了带隙计算方法的正确性。研究发现,相比于拉压平动单自由度谐振子,拉扭耦合双自由度谐振子会在板结构中打开一个新的弯曲波带隙。进一步分析归一化等效刚度系数对两个带隙位置和带宽的影响。最后,利用有限元方法计算10'5阵列超结构板的振动传递率,得出的振动衰减区域与由理论计算所得的带隙位置一致。有关结论可为轻质超结构板的多频带减振设计提供参考。
