基于光腔衰荡光谱技术的压力计校准方法

压强是工业生产过程中的一个重要参数,其准确测量是过程控制的关键。气体分子光谱线型和线宽取决于分子间相互作用和温度、气压等因素,利用窄线宽气体吸收光谱的压力展宽效应,可通过高分辨地测量气体吸收谱线得到压强信息,实现压力计校准。提出了一种基于光腔衰荡光谱技术和气体吸收谱线压力展宽效应的压力计校准方法。采用5.2 μm可调谐量子级联激光器,基于连续光腔衰荡光谱技术建立了压力计校准实验装置。室温下,测量水汽在1 877 cm-1附近的一吸收谱线,线宽为0.084 21 cm-1,重复性测量误差小于1.53×10-4 cm-1,对应的压强大小为98.12 kPa,检测灵敏度优于0.18 kPa,与高精度压力计读数98.14 kPa一致。利用测试谱线线宽与压强的关系得到压力展宽系数(0.087 12±0.000 965) cm-1·atm-1,与HITARN数据库参考值0.087 1 cm-1·atm-1一致。实验校准了一小量程压力计。结果表明基于光腔衰荡光谱的高分辨吸收谱线测量在压强检测和压力计校准领域具有很好的应用前景。     

基于Nd∶YVO_4晶体四波段腔面膜的研制

黄光激光器作为一种接近人眼敏感区域的激光器在诸多领域都发挥着重要的作用,而谐振腔又是激光器中重要组成部分.本文以Nd∶YVO4(c-cut)晶体为基底,利用真空镀膜设备研制出四波段腔面膜.通过分析膜系设计过程中膜层电场强度和优化膜系,使膜层中驻波场强得到合理分布,从而在理论上减小膜层损伤的可能性;通过TFCalc软件对测试结果进行工艺反馈分析,经过多次模拟实验,发现在不同控制波长下,采用相同监控方法监测不同的膜厚比例系数,通过调整工具因子解决了光谱曲线漂移的问题,制备出膜层牢固、化学性能稳定、满足四个波段光谱输出的黄光激光器腔面膜.     

Reflective plasmonic waveplates based on metal–insulator–metal subwavelength rectangular annular arrays

We propose and present a quarter-wave plate using metal–insulator–metal (MIM) structure with sub-wavelength rectangular annular arrays (RAA) patterned in the upper Au film. It is found that by manipulating asymmetric width of the annular gaps along two orthogonal directions, the reflected amplitude and phase of the two orthogonal components can be well controlled via the RAA metasurface tuned by the MIM cavity effect, in which the localized surface plasmon resonance dip can be flattened with the cavity length. A quarter-wave plate has been realized through an optimized design at 1.55 μm, in which the phase difference variation of less than 2% of the π/2 between the two orthogonal components can be obtained in an ultra-wide wavelength range of about 130 nm, and the reflectivity is up to ∼90% within the whole working wavelength band. It provides a great potential for applications in advanced nanophotonic devices and integrated photonic systems.     

N_2O的近红外腔增强吸收光谱技术研究

以外腔式可调谐、窄线宽近红外半导体激光为光源,以一对曲率半径r=1 000mm的宽带高反射率平凹镜(反射率R=99.97%)构成的腔长为650mm的对称高精度光学稳定腔,建立了腔增强吸收光谱系统。详细研究了纯净N2O气体、以及N2O和N2的混合气体在不同浓度和不同气压下、中心波长位于6 561.39cm-1的腔增强吸收光谱、光谱强度和谱线宽度,该腔增强吸收光谱系统的有效吸收光程可达1 460km。获得了光谱线宽与气体压强的关系曲线,导出了波数6 561.39cm-1处N2对N2O的压力展宽系数为(0.114±0.004)cm-1·atm-1。采用该腔增强吸收光谱系统,开展了N2O气体检测研究,建立可用于定量检测的N2O气体腔增强吸收光谱强度与气体浓度关系曲线,获得了2.34×10-7cm-1的检测灵敏度,多次重复测量的相对标准偏差(RSD)为1.73%,在微量N2O气体检测中具有很好的应用前景。     

CO2对790 nm附近水线的压力加宽和位移

采用高灵敏的激光光腔衰荡光谱技术研究了CO₂对¹⁶O水分子v²+3v³振动带跃迁线的压力诱导效应. 为了抑制水的自碰撞效应,水的压力在实验中低于0.5 Torr. 基于铷原子吸收线和超稳法布里-珀罗标准确定了跃迁谱线高达10^-5 cm^-1精度的绝对频率. 采用软碰撞模型对吸收线进行模拟,获得了对应的线形参数.     

非线性光学腔中的相位调制光机械动力学

研究了Fabry-Perot光学腔中包含一个光学参量放大器来增强腔场与机械振子之间的耦合的光机械动力学行为.在解析边带机制下用量子郞之万方程具体研究了振子的涨落光谱、光学多稳态行为、机械阻尼与修正共振频移和基态冷却.通过数值解讨论了辐射压力诱导机械振子和腔场的稳态振幅所展现的光学多稳态行为,同时也分析了辐射压力引起的修正共振频移和机械阻尼与参量增益、输入激光功率和参量相位这三个因素的关系.此外,随着调节泵浦场的参量相位,振子的涨落光谱呈现简正模式分裂.通过精确求解最终有效声子数论证了基态冷却.结果表明,机械振子的冷却由初始浴温度、机械品质因数和参量相位这个三个因素控制.参量相提供一个新的方法来操控非线性光机械动力学.     

A Conceptual Study of Cavity Aeroacoustics Control Using Porous Media Inserts

In this study, an integrated flow simulation and aeroacoustics prediction methodology is applied to testing a sound control technique using porous inserts in an open cavity. Large eddy simulation (LES) combined with a three-dimensional Ffowcs Williams–Hawkings (FW–H) acoustic analogy is employed to predict the flow field, the acoustic sources and the sound radiation. The Darcy pressure – velocity law is applied to conceptually mimic the effect of porous media placed on the cavity floor and/or rear wall. Consequently, flow in the cavity could locally move in or out through these porous walls, depending on the local pressure differences. LES with “standard” subgrid-scale models for compressible flow is carried out to simulate the flow field covering the sound source and near fields, and the fully three-dimensional FW–H acoustic analogy is used to predict the sound field. The numerical results show that applying the conceptual porous media on cavity floor and/or rear wall could decrease the pressure fluctuations in the cavity and the sound pressure level in the far field. The amplitudes of the dominant oscillations (Rossiter modes) are suppressed and their frequencies are slightly modified. The dominant sound source is the transverse dipole term, which is significantly reduced due to the porous walls. As a result, the sound pressure in the far field is also suppressed. The preliminary study reveals that using porous-inserts is a promising technology for flow and sound radiation control.     

基于LED的非相干宽带腔增强吸收光谱技术

介绍了基于可见光波段高功率LED作为光源的高灵敏度宽带腔增强吸收光谱技术,该系统的探测灵敏度通过测量NO₂在472.3～479.3 nm范围内的吸收得到验证。将中心波长为457 nm的高功率LED发出的宽带非相干光耦合进入92.5 cm长、由两片高反射率透镜组成的高精度光学谐振腔内,使用CCD光谱仪(HR2000)测量透过光学腔的光强信号。腔镜在472.3～479.3 nm波长范围内的反射率通过O₂-O₂聚合物的吸收确定,实验测量了一系列低浓度NO₂气体样品,采用差分光谱拟合技术在80 s的平均时间内NO₂浓度反演的统计不确定性约为3.1 ppb(ng·mL-1)。     

Self-Assembly of C-Methyl Calix[4]resorcinarene with 5,5′-Bipyrimidine

Abstract The X-ray crystal structure of the complex formed between 5,5′-bipyrimidine and C-methylresorcinarene is described. The structure (C₄₁H₄₅N₅O₁₂) is triclinic with a = 12.8610(10), b = 13.0560(10), c = 13.6068(11)?, α = 104.0730(10), β = 104.9260(10), γ = 111.6430(10)° and space group P-1. The structure reveals that the resorcinarene adopts a boat conformation and forms a three-dimensional network through hydrogen bonding to two water molecules and one dipyrimidine ligand. A single nitromethane molecule is included in the superstructure. Graphical Abstract Self-Assembly of C-Methyl Calix[4]resorcinarene with 5,5’-Bipyrimidine Charles L. Barnes(1) and Eric Bosch(2)* The X-ray crystal structure of the complex formed between 5,5′-bipyrimidine and C-methylresorcinarene is reported.      

三维洞穴环天线的耦合计算

在离子回旋共振加热中,对具有较复杂边界条件的洞穴环天线,通常为了简化计算忽略环天线水平分量的影响,按二维天线模型进行处理.给出了一种三维天线模型的详细计算过程,该模型与实际天线更加吻合,其计算结果可供洞穴环天线设计时参考. 关键词： 洞穴环 波加热 三维模型