一种适用于10.6μm外差探测的激光稳频系统

利用分子光谱线的斯塔克效应,将CO_2激光器频率锁定在NH_2D吸收线上,测试了斯塔克盒的巴邢(Paschen)曲线;讨论了频率稳定性的测试.用拍频的Allan方差评定,得到的长期频率稳定性为3.5×10~(-10),短期频率稳定性为7.86×10~(-10)。其中短期稳定性指标是该类稳频系统首次得到的.     

NH_2D斯塔克盒稳定CO_2激光器频率

利用NH_2D分子的斯塔克效应把CO_2激光器频率锁定在用电压控制的NH_2D吸收谱线上,由误差信号的漂移所得到的长期频率稳定性优于±34千赫/小时(即±1.2×10~(-9)/小时)。     

10.6μm双光路斯塔克稳频系统

本文介绍了利用斯塔克吸收效应稳定CO_2激光频率的理论和系统。并给出NH_2D斯塔克盒的吸收系数及系统误差信号的数学模型及实验结果。我们采用两套完全相同的斯塔克盒稳频系统,经光外差拍频;计算机实时取样处理;采用阿仑方差评定     

半导体激光器的原子法拉第反常色散光学滤波器光反馈稳频

为提高半导体激光器的频率稳定性，利用原子法拉第反常色散光学滤波器（FADOF）超窄带的选频透射特性，将其置于半导体激光器的外腔中作选频元件，采用光反馈的方法，使得透射率低的激光频率分量被抑制，透射率高的激光频率分量被加强，有效地实现了光反馈激光稳频。利用Cs原子法拉第反常色散光学滤波器工作于D2线852nm的4峰窄带透射状态。通过调节半导体激光器的温度和电流，调谐半导体激光器的输出波长，将激光器锁定在任何一个透射峰上，用26％的光反馈量，使稳频后的激光频率长期稳定性保持在75MHz／2h以内，而且采用这种稳频方法的输出激光中心波长一直稳定在频率基准上，没有单方向漂移。同时，还实现了Cs原子法拉第反常色散光学滤波器稳频半导体激光器结构的一体化，使其具有实用性。     

利用反馈环路稳定CO_2激光器的功率

本文报导CO_2激光器功率稳定环路的构成与性能。以荧光饱和吸收稳频的CO_2激光作基准,测定了功率稳定后的频率稳定性,结果表明,功率稳定可改善频率的长期稳定性。     

CO_2激光器的简单稳频

简单稳频是把被稳定激光器增益曲线的中心频率做为标准频率,用伺服电路把激光频率锁定在这一标准上.实验装置如图1所示.     

可调谐外差式激光偏频锁定

本文提出一种可调谐外差式激光偏频锁定方法,讨论了这种技术在频域内测量激光器瞬稳以及不同频谱振荡的激光器之间进行锁定的可能应用。给出了两台选支CO_2激光器上锁定实验的结果。考虑了本振频率不稳定性对锁定精度的影响。     

利用全光纤环形谐振器实现对单频激光器频率噪声的抑制

给出了利用全光纤环形谐振器实现对激光器频率噪声抑制的原理和实验结果。采用Pound-Drever-Hall的方法对锁定在铷原子吸收谱线上的激光进行稳频,实现了饱和吸收光谱与光纤环形谐振器双回路锁定。通过外差式马赫-曾德干涉仪来测量锁定后的激光器频率噪声发现,在频率100 Hz时,光纤环形谐振器对频率噪声的抑制度超过了40 d B。在1 Hz处,稳频激光器的频率噪声小于100 d B Hz2/Hz,其抑制度达到60 d B。     

频率直读高光谱纯度可调谐CO_2激光边带光谱仪及SF_6分子ν_3带多普勒受限光谱

用CdTe电光晶体将可调谐微波与频率锁定的CO_2激光混频,能产生可用于无多普勒光谱研究的高光谱纯度,宽调谐的边带。其独特优点是边带频率可直读;锁定的CO_2激光支线的频率f_L可查表精确得到,微波频率f_M可用微波频率计精确测得,因而边带频率f_(SB)可简单地由公式f_(SB)=f_L±f_M确定。 整个边带光源光谱仪可分为三个部分:稳频CO_2激光系统,可调谐微波系统及行波电光调制器,边带检测及跟踪系统。激光系统由一台光栅选支稳频CO_2激光器及一台光     

NH_2D斯塔克效应调制CO_2激光的研究

本文报告了利用NH_2D(氘化氨)分子的斯塔克效应对10.6μm,P(20)支线的CO_2激光进行强度调制的研究。激光器外部一个20cm长,电极间距为1.15mm的斯塔克盒上,加上440V直流偏压和400Hz,20V有效值的交流调制信号,在池内气压为4托时,     

（Li,Nb）掺杂SnO2压敏材料的电学非线性研究

研究了掺锂对SnO2压敏电阻器性能的影响.研究发现Li+对Sn4+的取代能明显提高陶瓷的烧结速度和致密度,且能大幅度改善材料的电学非线性性能.掺入x(Li2CO3)为1.0%的陶瓷样品具有最高的密度(P=6.77g/cm3)、最高的介电常数(ε=1851)、最低的视在势垒电场(EB=68.86V/mm)和最高的非线性常数(α=9.9).对比发现,Na+由于具有较大的离子粒半径,其掺杂改性性能相对较差.提出了SnO2@Li2CO3@Nb2O5晶界缺陷势垒模型.     

CaSi2O2N2:Ce3+/Eu2+荧光粉的发光性能研究

采用高温固相反应法制备了CaSi₂O₂N₂:C e³⁺/Eu ²⁺荧光粉,研究了分别掺杂Ce³⁺、Eu²⁺及Ce³⁺/Eu²⁺共掺 杂时荧光粉 的发光特性。CaSi₂O₂N₂:Ce³⁺在333 nm激发下得到宽波段的发射谱,发射峰 位于395nm,随着Ce³⁺浓度的增大,发 射波长出现明显的红移,猝灭浓度为1mol%。CaSi₂O₂N₂:Eu²⁺在397nm激发下得到峰值位于540nm处的宽波段发射谱, 猝灭浓度为1mol%。对于Ca0.99－2xSi₂O₂N₂:xCe ³⁺,xLi⁺,0.01Eu²⁺荧光粉,在333nm激发下,位于395nm处的发射峰十分微 弱,在540nm处有宽带发射,随着Ce³⁺浓度增大,位于540nm处的Eu²⁺的特征 发射显著增强。对于Ca0.98－ySi₂O₂N₂: 0.01Ce³⁺,0.01Li⁺,yEu²⁺荧光粉,在激发光波长 为333nm,Eu²⁺浓度较低时,可以观察到两个发射带,峰值分 别位于395nm及540nm,随着Eu²⁺浓度增加,位于395nm的 发射强度一直减小,而540nm处的发射强度先增加后减小,猝灭浓 度为0.4mol%。证实了Ce³⁺,Eu²⁺之间发生了有效的能 量传递。计算出Ce 3+、Eu²⁺之间能量传递的效率ηT,在Eu²⁺浓 度为 1mol%时ηT趋于饱和,达到97.7%。通过计算,得到Ce3+ 与Eu²⁺之间的能量传递方式为电偶极-电偶极相互作用。     

Temporal stability of circulating current in thin film Tl2Ba2CaCu2O8 and YBa2Cu3O7

The temporal stability of trapped transport current in annular thin film Tl₂Ba₂CaCu₂O₈ (TBCCO) and YBa₂Cu₃O₇ (YBCO) wafers has been accurately measured and has been found to be of suitable quality for the stringent requirements of nuclear magnetic resonance (NMR) magnets. No detectable decay, to the limit of the experimental apparatus (2*10^-14 Ω), was detected in those wafers with transport current at or below the critical current density J_c. The critical current density, as previously determined from 12 μm meander lines, was confirmed in a wafer with a width of 1.9 cm. The profile of trapped magnetic field resulting from induced current was modeled in order to assess its effect on the uniformity of an NMR magnet     

Effect of Ge-GeO2 co-doping on non-ohmic behaviour of TiO2-V2O5-Y2O3 varistor ceramics

An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO₂ on the TiO₂-V₂O₅-Y₂O₃ varistor ceramics. The result shows that as the doping contents of V₂O₅ and Y₂O₃ are 0.5 mol%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO₂ makes the highest α value (α = 12.8), the lowest breakdown voltage V_1mA (V_1mA = 15.8 V/mm) and the highest grain boundary barrier Φ_B (Φ_B = 1.48 eV), which is remarkably superior to the TiO₂-V₂O₅-Y₂O₃ varistor ceramics undoped with Ge and GeO₂ and mono-doped with Ge or GeO₂. The TiO₂-V₂O₅-Y₂O₃-Ge-GeO₂ ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties.     

选频~(14)CO_2-~(12)CO_2同位素激光器

我们研制了一台~(14)CO_2-~(12)CO_2同位素激光器,测量到激光谱线80条,其中40条是~(14)CO_200°1-(10°0,02°0)_I带的激光跃迁谱线,强线输出功率达4.0W以上;实验还观察到同位素的竞争效应,发现即使~(14)CO_2成份低于~(12)CO_2,其激光辐射仍占优势.     

Layered Al2O3-TiO2 compositedielectric resonators

Aluminium oxide displays a very low tanδ at microwave frequencies. It also possesses a remarkably high thermal conductivity, ideal for heat dissipation in high power satellite filters. However, its temperature coefficient of the resonant frequency (τ_f) is approximately 60 ppm/K. It is shown that the application of a film of titanium oxide which has a T_f of opposite sign (45O ppm/K) produces a composite in which the τ_f can be tuned to be zero over a wide temperature range. The tanδ of the composite at zero T_f is 3.3×10⁵ (Q=30000) at room temperature and at 10 GHz     

Low Rayleigh scatteringP2O5-F-SiO2 glasses

The Rayleigh scattering and infrared absorption losses of P₂ O₅-F-doped silica glass, which is a candidate material for ultra-low-loss optical fiber, were investigated experimentally. The Rayleigh scattering loss of 8.5 wt.% P₂O₅ and 0.3 wt.% F-doped SiO₂ glass is found to be 0.8 times that of pure silica glass. It is also found that the infrared absorption property of P₂O₅-F-SiO₂ glass is almost the same as that of pure silica glass. The minimum loss for the proposed composition is estimated to be 0.11 dB/km at 1.55 μm wavelength, and 0.21 dB/km at 1.3 μm wavelength     

Low-loss polyimide-Ta2O5-SiO2hybrid ARROW waveguides

A low-loss polyimide-Ta₂O₅-SiO₂ hybrid antiresonant reflecting optical waveguide (ARROW) is presented. The ARROW device was fabricated using both the organic and dielectric thin-film technologies. It consists of the fluorinated polyimide, tantalum pentoxide (Ta₂O₅), and silicon dioxide (SiO₂) hybrid layers deposited on a Si substrate. For transverse electric polarized light, the propagation loss of the waveguide as low as 0.4 dB/cm was obtained at 1.31 μm. The propagation loss for transverse magnetic polarized light is 1.5 dB/cm. An ARROW waveguide fabricated using the polyimide-Ta₂O₅ -polyimide material system is also presented for comparison     

Nonlinear optical properties ofK2La(NO3)5.2H2O and K2Ce(NO3)5.2H2O

The harmonic generating properties of potassium lanthanum nitrate (KLN) and potassium cerium nitrate (KCN) are described. These crystals have much larger nonlinear coefficients than potassium dihydrogen phosphate (KDP) and are nearly noncritically phase matched at room temperature for Type I frequency doubling of 1.064-μm light, and for Type II doubling of light near 0.95 μm. Thus, these crystals are useful for generating blue-green light by frequency doubling high-power near-infrared lasers. The crystal growth of KLN and KCN are described by the three component phase diagrams. Crystallographic data for KCN that confirms its structural similarity to KLN are presented. The optical absorption spectra of the two materials are discussed, and the linear refractive indexes are given