HL-2M 装置 CO2 色散干涉仪研制

研制了一套新型 CO₂ 激光色散干涉仪用于 HL-2M 装置初始放电期间的电子密度测量。该系统采用 基于激光倍频的色散测量原理,能够消除机械振动产生的相位误差。该系统使用全新的调相式信号调制,研发了 相应的数据采集/处理/上传系统。根据实验测量结果表明,CO₂ 激光色散干涉仪和微波干涉仪测量曲线基本一致, 色散干涉仪系统的测量精度约为 2×10¹⁷m⁻³,密度测量上限能达到 10²¹m⁻³。     

用于多信道色散补偿的Gires-Tournois干涉仪的特性分析

从Gires-Tournois(G-T)干涉仪的特性着手，分析一种基于G－T干涉仪的多信道色散补偿方法。该方法利用G－T干涉仪色散曲线的周期特性，同时对1.55μm窗口内的多个通信波长进行色散补偿，并实现色散补偿量的动态可调谐。     

基于电感耦合等离子体源的CO2色散干涉仪搭建和测试

在电感耦合等离子体源(ICP)装置上成功地搭建了一套没有减震系统的水平单道测量的CO₂色散干涉仪,用以测量等离子体的弦积分电子密度,并且与HCN干涉仪结果作对比,证明了CO₂色散干涉仪的可行性。     

中红外色散平坦渐减光纤设计

设计了一种以As2S3玻璃为纤芯、碲酸盐玻璃为微结构包层的锥形光子晶体光纤.该结构光纤兼具阶跃折射率光纤和光子晶体光纤双重特性,具有色散调制灵活性高且限制损耗低等优点.模拟结果表明:优化该光纤结构包层空气孔径、孔间距、纤芯直径等特征参量,使参量之间及参量与椎区长度之间满足特定线性关系时,该光纤在2~4.5μm中红外波段呈现色散平坦渐减特性;对该光纤微包层进行折射率~1.6的液体油填充处理,色散曲线对称性及平坦性得到进一步优化.该光纤在超短脉冲压缩与展宽、色散波、光孤子及中红外平坦超连续谱产生等领域应用潜力巨大.     

空芯光子带隙光纤色散特性的实验研究

针对空芯光子带隙光纤宽带宽、高效率、高精度的色散测量需求,本文基于干涉法,提出一种适用于测量空芯光子带隙光纤宽带色散的相位提取方法,建立了基于Mach-Zehnder干涉仪的色散测量系统,开展了空芯光子带隙光纤(HC-PBGF)色散特性的实验研究,重点对研制的19 cell HC-PBGF的色散特性进行了系统的实验研究.实际测量得到19 cell HC-PBGF在1400—1630 nm带宽范围内的基模色散曲线,开展了HC-PBGF的高阶模色散测量研究,测量得到了19 cell HC-PBGF四条高阶模色散曲线.实验测量结果与理论仿真结果吻合,研究成果为深入探究空芯光子带隙光纤的色散特性,推进其在高功率激光脉冲传输、大容量数据通信、光纤非线性等领域的应用具有重要意义.     

高灵敏度色散型慢光干涉仪的仿真研究

设计了一种基于慢光介质色散特性的新型干涉装置,研究其物理过程,证明利用慢光介质可以有效提高干涉仪的光谱灵敏度,并且光谱灵敏度与慢光介质的群折射率成正比。同时,进一步具体分析慢光介质GaAs的色散特性,给出研究色散型慢光干涉仪的一般性方法,并证明使用慢光介质GaAs在近红外区域可以提高光谱灵敏度2倍左右。     

用双棱镜测量液体的折射率

根据光在三棱镜中的色散关系和界面全反射,测量了液体的色散曲线和折射率.该题目作为全国大学生物理竞赛的基础实验试题,考察了学生的理论知识和动手能力.     

中红外色散平坦硫系光子晶体光纤设计及性能研究

本文以自制Ge20Sb15Se65硫系玻璃为基质材料,设计一种正八边形结构色散平坦型中红外硫系光子晶体光纤,并采用多极法对其中红外色散和传输特性进行数值研究.结果表明:控制该光纤占空比(d/Λ)在0.323—0.367之间,其色散及传输特性在3—5μm范围内可调.当孔间距Λ=3.4μm,孔直径d=1.1μm时,光纤在4.1—4.9μm波段的色散值在0.8—0.8 ps·nm 1·km 1波动,且具备单模低损耗传输(Loss0.049dB/m),小模场面积(Aeff8.46μm2)特性,适合于中红外非线性应用领域.     

光学玻璃的特殊色散机理

本文对光学玻璃的特殊色散机理进行了深入研究。研究认为,光学玻璃的特殊色散性能表征参数主要是相对部分色散偏离值ΔP_(g,F),ΔP_(g,F)绝对值越大,表明光学玻璃的特殊色散越大,越有利于消除光学系统的二级光谱。光学玻璃的特殊色散机理是由紫外和红外本征吸收引起。色散曲线中本征吸收峰的漂移和强弱将影响可见光区色散曲线斜率,进而使玻璃的相对部分色散偏离值变化。紫外本征吸收是由电子跃迁引起的;而红外本征吸收是由分子或分子集团振动造成的。开展特殊色散机理研究不仅可以深入揭示光学玻璃的"组分-结构-性能"关系规律,而且有助于开发特殊色散性能更优异的新型光学玻璃。     

Gires-Tournois干涉仪色散特性的研究

对多层薄膜Gires-Tournois(G-T)干涉仪的色散进行了精确数值计算并进行了实验研究.通过转动G-T干涉仪角度,其色散可以连续调节,具有合适参数的G-T干涉仪可以作为腔镜补偿腔内正啁啾,以压缩脉冲宽度.     

Movement measurement with a grating interferometer using sinusoidal phase-modulation

Movements of a surface profile are measured with a two-grating interferometer using sinusoidal phase-modulation. Since sinusoidal phase-modulating (SPM) interferometry can record a phase change due to the movement of an object in the interference signal, the SPM interferometer is suitable for measuring the movement of the object. Some experiments show that the two-grating interferometer can measure a sinusoidal vibration with amplitude of several tens of microns and a step movement with a magnitude of several microns.     

Intensity of the ν3 band of ozone from a study of its anomalous dispersion at 10 μm

An apparatus, consisting of a Michelson interferometer and a tunable CO₂ laser, is used to measure the anomalous dispersion of ozone in the 10-μm region. A line by line analysis leads to a new determination of the ν₃ band intensity of ozone which is independent of earlier measurements.     

高色散镜的设计和制备

设计和制备了两种高色散镜,分别在780-870 nm波长范围内提供约-800 fs² 群延迟色散补偿(group-delay dispersion,GDD)和在1030-1050 nm的波长范围内提供约-2500 fs²的群延迟色散补偿.设计的高色散镜用双离子束溅射方法进行制备.从白光干涉仪的测试结果可以看出,得到的-800 fs² GDD高色散镜和设计符合得比较好;-2500 fs² GDD的高色散镜用在掺Yb光纤激光器中很好的抑制了脉冲展宽.这是制备得到的国产高色散镜及在光纤激光器中应用的首次报道. 关键词： 高色散镜 群延迟色散 色散补偿 Yb光纤激光器     

Spectral-domain intermodal interference and the effect of a low-resolution spectrometer

Spectral-domain intermodal interference is analysed theoretically at the output of a few-mode optical fibre alone and at the output of the optical fibre in a tandem configuration with a Michelson interferometer. The theoretical analysis is performed under general measurement conditions when a broadband source and a low-resolution spectrometer of a Gaussian response function are considered and when the first- and second-order intermodal dispersion effects in the optical fibre are taken into account. The theoretical analysis is performed for two different examples of dispersion curves of a two-mode optical fibre and the effect of the limiting factors is specified.     

Harmonic interferometry in the visible and UV, based on second- and third-harmonic generation of a 25 ps mode-locked Nd:YAG laser

A second-harmonic interferometer using 25 ps pluses is presented, achieving a sensitivity of 9x10(-10) m in measuring line-integrated dispersion between 1064 and 532 nm. Using the same laser source, a third-harmonic interferometer is demonstrated for the first time to our knowledge, achieving a sensitivity of 7x10(-9) m in measuring line-integrated dispersion between 1064 and 355 nm. The prospect for the development and use of high-harmonic interferometry is discussed.     

Mode mixing of Alfvén waves in bismuth

We have investigated the propagation of Alfvén waves in bismuth at 4.2 K using a microwave interferometer at 34.45 GHz and applying magnetic fields up to 1 Tesla. At certain angles between the external magnetic field and the direction of propagation of the Alfvén waves in the crystal, we have observed intense oscillations of the amplitude and the phase of the interferometer curves. We explain these oscillations as due to a superposition of the two Alfvén wave modes. The phase velocities of the two modes are calculated from the measurements. Comparing them with a general dispersion relation we find good agreement between the theoretical phase velocities and the experimental values.     

The refractivities of water vapour for CO2 laser lines

The refractivities of water vapour in the 10 μm region at temperatures near 20°C are measured with an accuracy of 1% using a 10.6 μm CO₂/0.63 μm He-Ne laser interferometer with a 2 m long vacuum cell. The measured refractivities are 30% less than the value calculated by extrapolating the dispersion equation for water vapour in the visible region. From this result, the CO₂ laser is found to be useful as a light source for a three-wavelength laser ranging system of correcting for the air refractivity in the path.     

宽带啁啾镜对的设计和制备

设计了中心波长800 nm带宽约500 nm的啁啾镜对, 在550–1050 nm波长范围内提供约-60 fs²群延迟色散(group delay dispersion, GDD), 通过啁啾镜对的形式使GDD振荡波纹由单个啁啾镜的±100 fs²减小到±20 fs². 采用双射频离子束溅射方法进行制备, 用白光干涉仪进行色散性能测试, 从测试结果可以看出, 制备的啁啾镜的反射率、GDD性能和设计值符合得比较好. 制备出的550–1050 nm超宽带啁啾镜对在钛宝石激光器腔外进行色散补偿, 原输入脉冲由24–27 fs压缩到12 fs, 这是国产超宽带啁啾镜对的首次应用. 关键词： 超快激光 啁啾镜对 群延迟色散 色散补偿