Abstract ：

近年来,基于超材料的电磁吸波器件由于其宽带、易制备等优势而备受各国研究者的广泛关注.本文为实现宽带电磁低可探测,提出一种渐变电阻膜-介质复合结构的超材料吸波器.基于传输线理论和阻抗匹配原理,对强吸波条件进行了分析.在单元结构设计方面,采用遗传算法在多变量域内全局搜索最优解,快速地确定出能够兼顾低频与宽带吸波性能的超材料单元结构与电阻参数,并对器件吸波性能与吸波机理进行了深入的探讨.仿真结果表明,在垂直入射下,所设计的超材料吸波器对1.62—19.16 GHz (相对带宽168.8%)之间的入射波吸收率均大于90%,有效地向L和K波段拓展了吸收带宽.虽然在部分频段测试和仿真结果之间存在一定偏差,但两种类型的曲线随频率的变化趋势基本一致,这充分证明了所设计的超材料吸波器在低频宽带吸波领域具有潜在应用价值.

Keyword ：

渐变电阻膜 遗传算法 超材料吸波体

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Abstract ：

基于光栅效应的二维材料垂直结构可实现高灵敏度和宽光谱光探测器.本文报告了一种基于硒化铟(InSe)/二碲化钼(MoTe2)垂直异质结构的高灵敏度光电探测器,该探测器在 365～965 nm 波长范围内具有出色的宽光谱探测能力.顶层的InSe用作调节沟道电流的光栅层,MoTe2 则用作传输层.通过结合两种材料的优势,该光电探测器的响应时间为 21.6 ms,比探测率在365 nm光照下可以达到1.05×1013 Jones,在965 nm光照下也可达到109 Jones数量级.外量子效率可达 1.03×105%,显示出强大的光电转换能力.

Keyword ：

宽带光电探测器 超灵敏 光栅效应 二维材料

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Abstract ：

基于光栅效应的二维材料垂直结构可实现高灵敏度和宽光谱光探测器。本文报告了一种基于硒化铟（InSe）/二碲化钼（MoTe_2）垂直异质结构的高灵敏度光电探测器，该探测器在365～965 nm波长范围内具有出色的宽光谱探测能力。顶层的InSe用作调节沟道电流的光栅层，MoTe_2则用作传输层。通过结合两种材料的优势，该光电探测器的响应时间为21.6 ms，比探测率在365 nm光照下可以达到1.05×10~(13) Jones，在965 nm光照下也可达到10~9 Jones数量级。外量子效率可达1.03×10~5%，显示出强大的光电转换能力。

Keyword ：

光栅效应 宽带光电探测器 二维材料 超灵敏

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Abstract ：

本发明涉及中红外激光的技术领域，公开中红外后谱段增强宽带激光系统，能够获得中红外后谱段增强的高功率宽光谱激光输出，具有全光纤化、结构紧凑、中红外后谱段功率占比高的优点。这种中红外后谱段增强宽带激光系统包括：依次连接的锁模光纤激光器（1）、预放大器（2）、光纤展宽器（3）、放大器（4）、主放大器（5）、第一非线性光纤（6）、中红外放大器（7）和第二非线性光纤（8），每一部分均通过水冷或半导体制冷器，并采用光纤熔接进行连接。

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Abstract ：

为了实现水平方向和垂直方向入射电磁波的高效率、宽带反射型交叉极化转换,提出了一种新型的各向异性超表面结构。使用数值模拟仿真方法以及有限元分析方法进行研究。结果表明,所设计双十字结构超表面的电磁响应谱产生了4个共振区,从而导致了极化转换带宽的扩展。响应频段覆盖了Ku波段的10.7～18.7 GHz,其极化转换率(polarization conversion ratio,PCR)大于0.94。此外,在入射波角度为0°～50°内,都能保持较高的极化转换性能。该极化转换器具有简单的几何形状和较宽的工作频带,可能在伪装隐身、雷达通信和天线等应用中具有潜在的价值。

Keyword ：

Ku波段 双十字超表面 宽带 极化转换 计算仿真 等效电路

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In recent years, electromagnetic (EM) wave absorbing devices based on metamaterials have attracted widespread attention, due to their advantages such as broadband, easy preparation, and flexibility to tailor EM waves. Nevertheless, a review of the existing research reveals that the inherent sub-wavelength characteristics of metamaterials and metasurfaces impose certain constraints on their applications in low-frequency ranges. In order to achieve low detectability that takes into account both low-frequency and broadband absorbing performance, this work, presents a metamaterial absorber based on 5-layer gradient resistance film and dielectric composite structure, as shown in Fig. (a). To begin with, we introduce the structural design of the initial element, and based on this, the transmission line theory and impedance matching principle are used to analyze the strong wave absorption conditions of the absorber element. In terms of the element structure optimization, the genetic algorithm is adopted to globally search for the optimal solution in the multi-variable domain, resulting in the rapid determination of metamaterial elements’ configurations and resistance parameters that meet the design goals. In the simulation, the wave absorption performance and mechanism of the designed absorbing element are also investigated in an in-depth manner. Simulation results show that the designed metamaterial absorber can achieve more than 90% EM wave absorption in a frequency range of 1.62–19.16 GHz (with a relative bandwidth of 168.8%) under normal incidence of linearly polarized plane waves, which effectively expands the absorption bandwidth to the L band and K band. In addition, the simulations for oblique incidence at different polarizations provide strong evidence for the device’s insensitivity to both polarization and angle. The radar cross section (RCS) curves obtained by the time domain (TD) simulation illustrate that the novel structure can achieve more than 10 dB RCS reduction in a frequency range of 1.7–20 GHz. In the device's performance verification process, a metamaterial absorber with 20 × 20 elements and dimensions of 1.566 λl ×1.566 λl × 0.113 λl is fabricated and tested by using the bow method reflectivity test system. The absorptivity curves under 5° oblique incidence of different polarizations, show that the proposed metamaterial absorber can realize more than 80% EM absorption in an entire frequency range from 2 to 18 GHz, the test results of different polarizations are basically consistent. The test results at oblique incidence (θ ≥ 30°) show that although the measured and simulated curves exhibit discrepancies in certain frequency bands due to human error or material dispersion characteristics, the overall experimental results are consistent with our expectations, which fully proves that the designed metamaterial absorber has potential application value in the field of low-frequency and broadband EM absorption. © 2024 Chinese Physical Society.

Keyword ：

genetic algorithm metamaterial absorber gadient resistive film

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Abstract ：

The broadband grounded coplanar waveguide (GCPW) is the core component for calibrating oscilloscope broadband probes. To accurately measure the bandwidth of the oscilloscope probe, obtaining the transmission characteristics of the broadband GCPW becomes the key to achieving high-precision calibration. A GCPW time-domain twice measurement system is constructed based on femtosecond laser excitation picosecond electric pulse technology in the measuring principle of time-domain automatic network analyzer (TDANA). This involves taking two measurements in the system to solve the impulse response of the broadband GCPW (twice measurement method), thereby the frequency domain bandwidth can be obtained. The GCPW is designed with a post-wall structure (vias placed along the signal trace), and the processed sample is measured by the twice measurement method. In this way, the 3 dB bandwidth of our sample reaches 54. 2 GHz, which greatly agrees with the simulation result. The calibrated broadband GCPW can be used as a standard device for calibrating broadband probes, and its measured results can be effectively traced to the national benchmark for pulse waveform parameters. © 2023 Chinese Society for Measurement. All rights reserved.

Keyword ：

oscilloscope broadband probe frequency response time domain measurement sampling oscilloscope metrology broadband grounded coplanar waveguide

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Abstract ：

提出了一种电感值线性度高、Q值在多频点下保持恒定的新型宽带有源电感.它主要由回转器回路、带有一个外部电压调控端Vtune1的直流偏置模块、带有一个外部电压调控端Vtune2的共源-共栅调制支路以及两级电平转换电路等4 个电路模块组成.通过 4 个电路模块的相互配合及其 2 个外部调控端电压Vtune1、Vtune2的组合调节,使得新型有源电感具有如下的优秀电感综合性能:高的L值线性度,在多频点下具有高且基本恒定的 Q峰值,且在宽频带内具有高 Q值.基于 TSMC 0.18 μm CMOS工艺进行验证,结果表明,新型有源电感的 L 值线性度 L-1 dB高达-10 dBm;Q>10 的工作频带分别高达 2.7 GHz、3.45 GHz、3.7 GHz;在 2.6 GHz、3.75 GHz、5.2 GHz三个高频点下,分别取得了 1 100、1 089、1 102 的Q峰值,变化率仅为 2%.

Keyword ：

有源电感 高Q值 线性度

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Abstract ：

我们报道了一种基于SnS2/InSe垂直异质结的宽带光电探测器,其光谱范围为365-965 nm.其中,InSe作为光吸收层,有效扩展了光谱范围,SnS2作为传输层,与InSe形成异质结,促进了电子-空穴对的分离,增强了 光响应.该光电探测器在365 nm下具有813 A/W的响应度.并且,在965nm光照下它仍然具有371 A/W的高响应度,1.3×105％的外量子效率,3.17×1012 Jones的比探测率,以及27 ms的响应时间.该研究为高响应宽带光电探测器提供了一种新的方法.

Keyword ：

异质结 二维材料 宽带光电探测器

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力学超材料的基本单元是人工微结构,其超常的特性并非依靠自然材料组分或者是本构关系,而是取决于其微结构的特征。因此,对于超材料微结构的设计是实现其力学性能优化的重点。一般来讲,超材料一旦设计为确定结构,其力学性能将难以改变,本文引入一种可调多稳态力学超材料,通过改变单胞中曲梁的刚度实现对结构带隙的调节。本文以具有双自由度的弹簧振子系统对可调多稳态力学超材料微结构进行动力学等效,研究其一维周期结构的带隙形成机理。通过理论分析以及有限元模拟得到系统的等效参数,建立动力学模型,求解结构的弹性波带隙,并利用Comsol软件对结果进行验证。结果表明,等效系统能够有效揭示可调多稳态力学超材料带隙的形成机理。可调多稳态力学超材料能够降低带隙低频、拓宽带隙范围、实现"低频宽带"的效果,拓展力学超材料的应用范围。

Keyword ：

带隙调节 多稳态 动力学等效 力学超材料

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