姚建铨 Yao Jianquan's research while affiliated with Tianjin University and other places

... A metamaterial absorber is a device that achieves high-efficiency absorption of electromagnetic waves at specific frequencies and bands, achieved by designing the shape of the metamaterial structure. [1][2][3][4][5][6][7][8][9][10] Since Landy first proposed the perfect metamaterial absorber in 2008, the metamaterial absorber has attracted wide attention from researchers. 11 The range of research on metamaterial absorbers extends from the microwave band to the terahertz band, visible light band, near-infrared band, and far-infrared band, i.e., nearly all the electromagnetic wavelengths shorter than can be accommodated with ordinary electronics. ...

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Reverse design of metamaterial absorbers based on an equivalent circuit

... 其中, Z表示总阻抗, 包括金属多层膜、 衬底和空气的 共同贡献 [204] ; w 0 是束腰长度, 这里是指激光脉冲的光 [205][206][207] . 一方面, 由于太赫兹电磁波 在通信 [208] 、安检 [209] 、生物检测 [210] 等方面具有不可 替代的优势, 使得其具有非常丰富的应用场景; 另一方 面, 太赫兹频段正好对应于凝聚态和材料物理多种相 互作用的能量尺度, 为科学研究提供了一种有效的探 测源 [211] . ...

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Progress in ultrafast spintronics research

... The smaller the ratio of the two, the smaller the diffuse reflectance it shows. Compared with VIS and IR, under the same surface roughness, the THz wavelength is longer, and the surface of the component has a more specular reflectance [28]. In addition, the common blackened coating will have a large decrease in the absorption in the THz spectral range, which will increase the reflectance. ...

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Stray Light Analysis and Suppression of the Visible to Terahertz Integrated Cloud Detection Optical System

... It has been considered that self-phase modulation caused by relaxation oscillation and self-pulsation in the seed laser causes the linewidth broadening [15]. In 2018, Bai et al. studied the laser linewidth of the amplifier and believed that amplified spontaneous emission (ASE) caused laser linewidth broadening during the amplification process [16]. As can be seen from the above studies, some consider ASE to be one of the factors affecting laser linewidth during the amplification process because the spontaneously emitted photons are not in phase with the laser, and so a phase fluctuation appears, leading to a broadened laser linewidth [17]. ...

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Influence of amplified spontaneous emission on laser linewidth in a fiber amplifier

... Recently, with the increasing demand in RCS scaled measurement of large targets, the technology of THz radar and the THz RCS measurement systems have attracted increasing research attentions [3][4][5][6]. In accordance with the approach of THz wave generation and detection [7,8], various types of THz RCS measurement systems have been constructed, including THz laser-based systems [9][10][11], THz time-domain spectroscopy (THz-TDS)-based systems [12][13][14][15], and solid-state THz systems [16,17]. The fast development of THz RCS measurement systems provides a potentially improved method for studying the scattering behaviors of large targets. ...

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Study on Terahertz RCS Scaled Measurements for Metal Plates of Rough Surfaces

... Thus, pump absorption is relatively low, restraining the overall optical efficiency of Raman lasers. In 2014, a wavelength-locked in-band pumping LD is intro- duced to actively Q-switched self-Raman lasers by Sheng et al. [20] and Ding et al. [21] The pump absorption fraction of 0.3- at.% doped Nd:YVO 4 crystal with a length of 10 mm increases from 77% to 86% by wavelength-locked LD pumping. [21] In this paper, we report a cw efficient self-Raman laser operation at 1176 nm based on a composite YVO 4 /Nd:YVO 4 /YVO 4 crystal. ...

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An efficient continuous-wave YVO 4 /Nd:YVO 4 /YVO 4 self-Raman laser pumped by a wavelength-locked 878.9 nm laser diode

... In general, Thulium-doped fibers are designed with cladding over the core. In the same year, Tianjin University [11] used a double-cladding design and conducted a study on its temperature. They found that Thulium-doped fiber amplifiers are suitable for lower peak temperatures, with larger pump optical power and a Gaussian distribution function of the absorption cross-section. ...

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Modeling of Output Spectra and Numerical Simulation of Thulium-doped Broadband Fiber Light Sources at 1400-1520nm, 1800-2000nm

... Terahertz waves are electromagnetic waves with frequencies ranging from 0.1 THz to 10 THz [1,2]. They have high transmission, high resolution, broadband and other high quality characteristics. ...

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A High-quality Broadband Tunable Terahertz Metamaterial Absorber Based on Graphene

... The interplay between defect states and free charge carriers is not yet fully understood in the devices based on emergent technologies [72]. Carrier mobilities in conductive polymers, which are dielectric semiconductors, are also typically much lower than in ordered lattice semiconductors and cannot be measured using the same time-of-flight (TOF) methods [73,74]. The carrier mobility depends on the film thickness, the maximum number possible of optical generated carrier, incident pulse width, the dielectric relaxation time. ...

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ZnO-doped PFPAMA: a novel transparent conducting polymer for fast photodiodes

... Then the sensitive liquids are filled into the core. Selective filling technology is used in the above two procedures to avoid the coating and filling in cladding holes [8]. After the materials are encapsulated, the two end faces of kagomé fiber will be spliced with two single-mode fibers, respectively, to realize the transmission and collection of optical signals. ...

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Numerical analysis of a novel refractive index and temperature sensor based on a kagomé hollow-core photonic crystal fiber