准连续可调的NH3分子光泵亚毫米波激光

以NH_3分子气体为工作物质,对CO_2激光和微波同时作为泵浦源的光泵亚毫米波激光系统的密度矩阵方程的求解,获得光泵激光器的频率特性和增益特性。理论计算结果表明:利用光泵激光中的超喇曼过程,改变微波频率,可以产生频率准连续可调的亚毫米波信号;利用谱线的压力增宽,调节激光的腔长,改变其纵模频率,也可以获得准连续可调的亚毫米波信号。     

Nd^3＋：YAG球的声子模谱结构与腔效应

利用黄昆方程从理论上分析了在球形激光Nd^3 ,YAG晶体腔中构成的声子场模谱结构相对体材料在性质和数量上的变化,并利用RENISHAW2000型共焦显微喇曼光谱仪实测了Nd^3 ,YAG晶体球的喇曼光谱,发现喇曼位移在50－150cm^-1的范围内,明显存在声子场腔效应现象,根据理论计算结果和实验结果论证了腔量子声学效应存在的可能性。     

Nd~(3 ):YAG球的声子模谱结构与腔效应

利用黄昆方程从理论上分析了在球形激光 Nd3 :YAG晶体腔中构成的声子场模谱结构相对体材料在性质和数量上的变化 ,并利用 RENISHAW 2 0 0 0型共焦显微喇曼光谱仪实测了 Nd3 :YAG晶体球的喇曼光谱 ,发现喇曼位移在 5 0～ 15 0 cm- 1 的范围内 ,明显存在声子场腔效应现象 .根据理论计算结果和实验结果论证了腔量子声学效应存在的可能性 .     

光泵远红外激光中多光子过程的饱和效应

1970年以来,用红外激光泵浦分子气体,激发其内部的单光子跃迁或喇曼散射过程以产生可调谐的亚毫米波激光的工作不少。但这方法往往存在红外光泵输出的频率是否与分子气体的振一转能级间隔相匹配的问题。一个解决办法是将样品置入电场中(Laser Stark Spectroscopy),调谐分子能级以达到共振。由于Stark效应,受激分子能级因电场干扰发生位移,不能直接测量无微扰分子的能级参数,而且所发出的     

小牛胸腺DNA的激光喇曼谱

用常规喇曼和表面增强喇曼的方法获得了小牛胸腺ＤＮＡ固体纤维和水溶液的激光喇曼谱，样品的喇曼特征谱带与国外文献及国内紫外共振喇曼法得到的谱图基本一致，由此可分析出样品的构象，基团归属等信息，证明喇曼光谱是用于测量生物分子结构的一个有力武器。     

核酸的激光喇曼光谱

本文研究了核酸的激光喇曼光谱与它的结构及生化功能的关系。确认应用激光喇曼光谱研究核酸是具有信息量大、高灵敏度及高分辨本领的。     

可调谐远红外激光的电微调

本文应用斯塔克效应消除CH_3F 分子能级对M 的简并,使分子能级按量子数J,K,M展开。在四能级近似下,计算CH_3F 分子气体中受激喇曼散射的调谐和增益特性,发现在调谐和增益特性曲线中,由于交流斯塔克效应及其他原因引起的空隙有可能被填补,从而改善了调谐和增益特性,这对可调谐光泵亚毫米波激光器的实验工作具有一定的意义。     

银电极表面吸附分子的表面增强喇曼散射(SERS)光谱

本文介绍了吸附于粗糙银电极表面的毗啶等四种喇曼活性分子的表面增强喇曼散射(SERS)光谱的实验研究工作及所得到的 SERS 光谱。研究了电极表面增强效应的淬灭、保存和再生条件。实验结果表明,电极表面的粗糙度对喇曼活性分子的喇曼光谱表面增强效应有较大影响,电极的外加电位对表面增强效应也有较大影响。最后,对SERS 光谱表面增强效应的起因进行了初步讨论。     

含喇曼效应的暗孤子解

应用变分法,讨论喇曼效应对光纤中暗孤子传输特性的影响,导出了暗孤子参数演化的方程组,并得出了存在喇曼效应时暗孤子的孤波解.     

甲醇和乙醇的激光喇曼光谱

采用激光喇曼方法,对甲醇和乙醇液体样品进行了喇曼光谱研究,得到了上述样品的喇曼光谱,并对其进行了归属.经过分析比较,给出了检测甲醇的特征谱线,为假酒鉴别、深入研究甲醇和乙醇的能级结构等提供了可供借鉴的参考.     

SVD算法在亚毫米波付里叶变换谱中的应用

本文介绍了自回归谱分析法中的奇异值分解法(SVD算法)在亚毫米波付里叶变换谱中的应用.SVD算法和前后向最小二乘法(LS算法)相比,它们具有相同的分辨率,但SVD算法能够消除LS算法中出现的假峰和病态的问题,具有更强的抗噪声能力,因而SVD算法比LS算法更加稳定可靠.还讨论了SVD算法的阶数和有效奇异值个数的选择问题.     

Photonics: lasers producing tailored beams

Compact lasers that can produce a range of beam patterns are important for progress in several areas, including the improvement of optical tweezers, ultra-high-density optical memory and microfluidics. Here we engineer photonic crystals to generate semiconductor lasers that produce a range of beam patterns while maintaining stable single-mode oscillation. Our results could contribute to the realization of compact lasers that are capable of producing diverse beam patterns on demand.     

强激光高能量密度物理的若干进展和展望

随着大能量高功率激光和短脉冲超强激光技术的发展,人们可以在单位时间、单位空间内实现极高的能量密度,产生一系列原本只存在于天体或者核爆中的极端物理条件．对这种高能量密度条件下的物质规律的研究不仅极大地拓宽了物理学的研究领域,而且促进了不同学科之间的交叉与融合．本文将首先简单介绍强激光驱动的高能量密度实验室天体物理方面的几个进展,之后对下一代极端相对论激光物理的发展和影响进行展望．     

Single-nanowire electrically driven lasers

Electrically driven semiconductor lasers are used in technologies ranging from telecommunications and information storage to medical diagnostics and therapeutics. The success of this class of lasers is due in part to well-developed planar semiconductor growth and processing, which enables reproducible fabrication of integrated, electrically driven devices. Yet this approach to device fabrication is also costly and difficult to integrate directly with other technologies such as silicon microelectronics. To overcome these issues for future applications, there has been considerable interest in using organic molecules, polymers, and inorganic nanostructures for lasers, because these materials can be fashioned into devices by chemical processing. Indeed, amplified stimulated emission and lasing have been reported for optically pumped organic systems and, more recently, inorganic nanocrystals and nanowires. However, electrically driven lasing, which is required in most applications, has met with several difficulties in organic systems, and has not been addressed for assembled nanocrystals or nanowires. Here we investigate the feasibility of achieving electrically driven lasing from individual nanowires. Optical and electrical measurements made on single-crystal cadmium sulphide nanowires show that these structures can function as Fabry-Perot optical cavities with mode spacing inversely related to the nanowire length. Investigations of optical and electrical pumping further indicate a threshold for lasing as characterized by optical modes with instrument-limited linewidths. Electrically driven nanowire lasers, which might be assembled in arrays capable of emitting a wide range of colours, could improve existing applications and suggest new opportunities.     

光路失效分析的检测方法研究

为提高激光点火的可靠性,检测光路中存在光纤的弯曲、端面污染、划痕或烧蚀等失效因素造成的损耗,经过双向色膜和双光纤探测器的结构设计,建立了一套双光纤、双光源的自检系统,使检测光的接收率达到6%以上.实验结果表明,获得的光纤损耗在650nm检测光和808nm发火光下损耗半经验公式,从检测光路损耗能推导出发火光路损耗,解决了激光点火技术在工程实际应用中自检测难题.     

A steady-state superradiant laser with less than one intracavity photon

The spectral purity of an oscillator is central to many applications, such as detecting gravity waves, defining the second, ground-state cooling and quantum manipulation of nanomechanical objects, and quantum computation. Recent proposals suggest that laser oscillators which use very narrow optical transitions in atoms can be orders of magnitude more spectrally pure than present lasers. Lasers of this high spectral purity are predicted to operate deep in the 'bad-cavity', or superradiant, regime, where the bare atomic linewidth is much less than the cavity linewidth. Here we demonstrate a Raman superradiant laser source in which spontaneous synchronization of more than one million rubidium-87 atomic dipoles is continuously sustained by less than 0.2 photons on average inside the optical cavity. By operating at low intracavity photon number, we demonstrate isolation of the collective atomic dipole from the environment by a factor of more than ten thousand, as characterized by cavity frequency pulling measurements. The emitted light has a frequency linewidth, measured relative to the Raman dressing laser, that is less than that of single-particle decoherence linewidths and more than ten thousand times less than the quantum linewidth limit typically applied to 'good-cavity' optical lasers, for which the cavity linewidth is much less than the atomic linewidth. These results demonstrate several key predictions for future superradiant lasers, which could be used to improve the stability of passive atomic clocks and which may lead to new searches for physics beyond the standard model.     

Raman injection laser

Stimulated Raman scattering is a nonlinear optical process that, in a broad variety of materials, enables the generation of optical gain at a frequency that is shifted from that of the incident radiation by an amount corresponding to the frequency of an internal oscillation of the material. This effect is the basis for a broad class of tunable sources known as Raman lasers. In general, these sources have only small gain (approximately 10(-9) cm W(-1)) and therefore require external pumping with powerful lasers, which limits their applications. Here we report the realization of a semiconductor injection Raman laser designed to circumvent these limitations. The physics underlying our device differs in a fundamental way from existing Raman lasers: it is based on triply resonant stimulated Raman scattering between quantum-confined states within the active region of a quantum cascade laser that serves as an internal optical pump--the device is driven electrically and no external laser pump is required. This leads to an enhancement of orders of magnitude in the Raman gain, high conversion efficiency and low threshold. Our lasers combine the advantages of nonlinear optical devices and of semiconductor injection lasers, and could lead to a new class of compact and wavelength-agile mid-and far-infrared light sources.     

衍射极限倍因子M2的实验测量

目的测量He—Ne激光器（波长632．8nm）和半导体激光器（波长650nm）的肘。因子。方法根据ISO／TC172／SC9／WG1 N80文件对M^2因子的测量原理及要求，用美国Spirieon公司生产的LBA-300PC激光束分析仪，沿光传播方向在不同z位置，测出光束宽度，由测量数据进行双曲线拟合，确定束腰直径和远场发射角，计算M^2因子。结果所测全内腔玻璃外壳He—Ne激光器的M^2=1．422，半导体激光器的M^2=1．599。结论市场上流通的He—Ne激光器和廉价的半导体激光器大都可以用于医学应用，不适于用作干涉计量或全息照相等方面的应用。     

两台单模激光的耦合和混沌同步

对空间上相互耦合的两台单模固体激光器的动力学行为进行了分析,当其中一台激光的泵浦受到调制时,对于不同的参量,两台激光输出的强度会出现混沌同步和失去同步的情况。