半导体纳米粒子Bi2S3和NiS的非线性吸收特性

测量了两种纳米粒子Bi2S3和NiS的光限幅特性和非线性光学响应,测量了非线性吸收特性,数值模拟计算了Bi2S3的非线性吸收系数β≈9cm/GW,NiS非线性吸收系数β≈8cm/GW.     

半导体纳米粒子Bi2S3和NiS的非线性吸收特性

测量了两种纳米粒子Bi2S3和NiS的光限幅特性和非线性光学响应，测量了非线性吸收特性，数值模拟计算了Bi2S3的非线性吸收系数β≈9cm/GW, NiS非线性吸收系数β≈8cm/GW.     

半导体纳米粒子Bi2S3和NiS的光限幅特性研究

研究了Bi2S2和NiS半导体纳米粒子的光限幅特性,测得了Bi2S3非线性阈值为0.11 J/cm2,NiS的非线性阈值为0.21 J/cm2.对两种样品进行了开孔Z-scan的实验,计算可知Bi2S3非线性吸收系数β≈9 cm/GW,NiS的非线性吸收系数β≈8 cm/GW.在NiS半导体纳米粒子的乙醇溶液进行闭孔Z-scan时,发现样品有自聚焦的特性,也就是说样品的非线性折射率系数n2＞O,计算得y≈2.66×104 cm2/GW.     

CdS0.2Se0.8纳米晶掺杂玻璃的超快非线性吸收特性

利用飞秒脉冲通过Z扫描技术和泵浦-探测技术研究了CdS0.2Se0.8纳米晶掺杂的硼酸盐玻璃滤波片RG665的非线性吸收特性。研究结果表明在800 nm波长 130 fs脉冲激光作用下,RG665滤波片表现较强的非线性吸收特性。通过理论分析拟合实验结果证明RG665滤波片在800 nm下的非线性吸收包含双光子吸收及双光子吸收诱导的激发态吸收两部分,得到双光子吸收系数为0.05 cm/GW,激发态吸收截面为e=310-23 m2,以及导带中低能态电子和导带底电子的寿命分别为13 ps和210 ps。研究结果表明CdS0.2Se0.8纳米晶体掺杂的玻璃是一种很好的非线性光学材料。     

CS2宽带光限幅和非线性吸收特性研究

利用ns脉冲激光,研究了CS2在420-470nm波长范围内的非线性吸收和光限幅特性。实验结果表明,CS2对420-450nm波长的脉冲激光具有大的非线性吸收和优良的光限幅性能,随着波长的增加,其非线性吸收和光限幅性能逐渐减小;CS2良好的宽带光限幅性能源于其大的非线性吸收,其非线性吸收机制为双光子吸收（TPA）以及由TPA诱导的激发态吸收（ESA）。     

两种无机巢形金属团簇的非线性吸收及光限幅特性研究

用 5 32nm ,8ns激光脉冲系统研究了两种巢形金属团簇非线性吸收和光限幅特性。Z 扫描和光限幅的实验结果表明 ,团簇的非线性吸收和光限幅特性强烈依赖于重金属原子。根据有效激发态吸收理论分析了光限幅机理     

线性及非线性吸收热致光学限幅效应的讨论

本文分别对在连续和脉冲激光入射下，对由材料线性和非线性吸收产生在热致光限幅效应进行了研究，给出了产生最大光限幅效应的条件，为热效应光学限幅应用于光学器件的激光防护提供了理论依据。     

纳米复合材料Ag:Bi2O3的光学响应与超快开关效应

系统地研究了AgBi2O3纳米复合材料的光学特性、飞秒激光三阶非线性极化率以及超快响应、介电函数随纳米金属颗粒成分与尺寸的变化关系.同时给出了该材料与表面等离子共振相关的线性吸收的红移规律.由于该复合体系在类似材料中具有比较大的三阶非线性极化率与超快开关效应,在超快全光开关材料方面具有潜在应用价值.     

活性炭及炭载铂纳米粒子光限幅特性

利用光限幅实验,研究了纯活性炭纳米粒子和炭载铂纳米粒子水溶液的非线性吸收特性,发现活性炭纳米粒子具有反饱和吸收到饱和吸收的特性,Pt纳米粒子对炭载铂纳米粒子体系具有表面等离子局域增强效应。     

基于非线性折射和吸收效应光限幅器的优化分析

推导了高斯光束入射情况下,基于非线性折射和非线性吸收效应限幅器的出射功率表达式,数值模拟了不同情况下的限幅曲线及最佳钳位输出功率和介质最佳限幅位置随主要参数的变化曲线.研究表明:当非线性吸收效应较弱时,输出功率随入射功率的增加存在衰减震荡现象,但是非线性吸收作用使其在高入射功率下的震荡周期显著大于低入射功率时的周期;随非线性吸收效应的增强,出射功率的震荡现象消失;当光阑线性透过率大于0.75时,强非线性吸收效应使限幅器仍然有很好的限幅能力;对于任意限幅光阑线性透过率的限幅器,非线性吸收相移和非线性折射相移之比存在某个临界值来区分吸收效应是提高还是降低器件的限幅能力.     

Deposition of thin Bi2Te3 and Sb2Te3 films by pulsed laser ablation

Bi₂Te₃ and Sb₂Te₃ films were obtained by pulsed laser ablation. The films were deposited in vacuum (1 × 10⁻⁵ Torr) on single crystal substrates of Al₂O₃ (0001), BaF₂ (111), and fresh cleavages of KCl or NaCl (001) heated to 453–523 K. The films were 10–1500 nm thick. The structures of the bulk material of targets and films were studied by X-ray diffractometry and transmission high-energy electron diffraction, respectively. Electrical properties of the films were measured in the temperature range of 77–300 K. It is shown that the films possess semiconductor properties. Several activation portions are observed in the temperature dependences of resistivity; the energies of activation portions depend on the film thickness and crystallite size.     

Bi_2O_3和Sb_2O_3的预复合对ZnO压敏电阻性能的影响

采用固相法对Bi2O3和Sb2O3进行了预复合,并研究了不同比例的Bi2O3与Sb2O3预复合对ZnO压敏电阻致密度,晶粒结构和电学性能的影响。结果表明:当Bi2O3与Sb2O3的摩尔比为0.7:1.0时,ZnO压敏电阻的综合性能最优,其晶粒生长得最为均匀致密,电位梯度达到361V/mm,非线性系数为86,漏电流密度为7×10–8A/cm2;另外,在耐受5kA电流下的8/20μs脉冲电流波后,其残压比和压敏电压变化率分别为2.6和2.5%。     

Synthesis and Characterization of Polythiophene/Bi2Te3 Nanocomposite Thermoelectric Material

To achieve low thermal conductivity, polythiophene (PTh)/bismuth telluride (Bi₂Te₃) nanocomposite has been prepared by spark plasma sintering using a mixture of nanosized Bi₂Te₃ and PTh powders. Bi₂Te₃ powder with spherical-shaped particles of 30 nm diameter and PTh nanosheet powder were first prepared by hydrothermal synthesis and chemical oxidation, respectively. X-ray diffraction analysis and scanning electron microscopy observations revealed that the hybrid composite consists of PTh nanosheets and spherical Bi₂Te₃. The organic PTh acts as an adhesive in the composite. Transport measurements showed that the PTh in the Bi₂Te₃ matrix can reduce its thermal conductivity significantly, but also dramatically reduces its electrical conductivity. As a result, the figure of merit of the composite is lower than that of pure Bi₂Te₃ prepared under the same conditions. The maximum value of ZT for the sample with 5% PTh (by weight) was 0.18 at 473 K, which is rather high compared with other polymer/inorganic thermoelectric material composites.     

Effect of annealing on the structure of Bi2Te3-Bi2Se3 films

The crystallization dynamics of Bi₂Te₃-Bi₂Se₃ polycrystalline films annealed at 200–230°C has been investigated. The formation of ordered blocks 70—150 nm in size, depending on the annealing time and temperature, is observed.     

Interaction of electrical active intrinsic defects in Sn-doping Bi2Te3

Impure Sn produces the resonant states on the background of the allowed spectrum of states of the valence band in Bi₂Te₃. A high density of the resonant states stabilizes the Fermi level _F. Stabilization of _F leads to an enhancement of the volume homogeneity of the distribution of electrically active components.We report the results of an experimental study on the influence of doping Sn atoms on hole concentrations of Bi₂Te₃ and replace the part of Te atoms on Se atoms and the part of Bi atoms on Sb atoms. The estimation of the influence of resonant states on the process of crystal defects formation has been attempted theoretically.     

Photoinduced self-developing relief gratings in thin filmchalcogenide As2S3 glasses

Experimental observation and study of light induced relief gratings in chalcogenide glasses is presented. Holographic exposure of the glass film by near bandgap light leads to a real-time periodic thickness self-expansion without further processing. The dynamics of surface modulation is not monotone with respect to the exposition. These modulations demonstrate a strong memory effect, but can be erased by heating near the glass transition temperature