TiN镀层的一级和二级Raman散射

我们观测到了TiN镀层的一级和二级Raman散射,初步研究了TiN镀层的沉积参数和镀层性质对Raman谱的影响。结果表明TiN镀层的Raman散射不同于体材料氮化钛的Raman散射,特别是在二级Raman散射部分。     

光纤维中的喇曼混频

我们在656厘米^-1到1343厘米^-1的频率范围研究了光纤维的调谐喇曼混频(RM)效应。在实验中观察到下列现象:相干反斯托克斯喇曼散射(CARS)的大小与逆喇曼吸收(VRA)的大小成反比;RM对受激喇曼散射(SRS)的强度分布有强烈影响。除了观测到相干斯托克斯(CSRS)和CARS辐射,还观测到二级相干斯托克斯(SOCSRS)和相干反斯托克斯(SOCARS)辐射。对实验结果进行了讨论。 关键词：     

Absolute efficiency and dispersion of Raman scattering by phonons in silicon

We have measured the absolute Raman efficiency for first order scattering of the optical zone center phonon with two different incident photon energies (1.16 and 0.94 eV) by comparison with the Raman scattering from diamond. A value significantly lower than the experimental data published previously in this region has been found. For the first order scattering no dispersion of the scattering efficiency has been observed at the indirect gap, in contrast to the second order scattering which shows a pronounced resonance behaviour in this energy range.     

Raman scattering and phonon density of states of an a-15 compound: V3Si

The defect induced Raman scattering of non-stoichiometric V₃Si is very weak. It is compared with the phonon density from neutron data. In addition, allowed first and second order Raman scattering are observed.     

From anti‐Stokes photoluminescence to resonant Raman scattering in GaN single crystals and GaN‐based heterostructures

The progress on anti‐Stokes photoluminescence and Stokes and anti‐Stokes Raman scattering in GaN single crystals and GaN/AlN heterostructures is reviewed. Anti‐Stokes photoluminescence investigated in the past was primarily attributed to two‐photon absorption, three‐photon absorption, and phonon‐assisted absorption. On the other hand, anti‐Stokes Raman scattering was used to determine electron‐phonon scattering time and decay time constant for longitudinal‐optical phonons. In a typical high electron mobility transistor based on GaN/AlN heterostructures, strong resonances were reached for first‐order and second‐order Raman scattering processes. Therefore, both Stokes and anti‐Stokes Raman intensities were dramatically enhanced. The feasibility of laser cooling of a nitride structure has been demonstrated. Anti‐Stokes photoluminescence and Raman scattering have potential applications in upconversion lasers and laser cooling of nitride ultrafast electronic and optoelectronic devices.     

用拉曼散射分析碲镉汞中的缺陷

本文分析了碲镉汞（HgCdTe或MCT）中Te沉淀相,Hg空位的拉曼散射峰,以及碲镉汞表面完整性与它的二级拉曼散射峰的关系,MCT中的Te沉淀相的拉曼峰位于125和145cm^-1处,此峰与标准的Te三角晶系的拉曼峰相比,往高能方向移动了2cm^-1,这表明Te沉淀相受到了压应力的作用,MCT中位于108cm^-1处微弱的拉曼峰来源于Hg空位,此峰只在p型和包含有反型层的MCT中出现,在n型的MCT中几乎不出现,MCT的拉曼二极散射峰对其表面完整性非常敏感,表面完整性好的拉曼峰很明显,而表面完整性较差的峰则不太明显,此峰的1LO（T）模的强度测量对晶体制备过程中的表面分析也可能供有用的信息。     

Non‐degenerate second‐order scattering and difference combination bands in infrared‐pump/anti‐Stokes resonance Raman‐probe experiments

Non‐degenerate second‐order scattering due to interaction of infrared and ultraviolet pulses is observed in picosecond infrared‐pump/anti‐Stokes Raman‐probe experiments under electronic resonance conditions. We detected resonance hyper‐Rayleigh scattering at the sum frequency of the pulses as well as the corresponding frequency‐down‐shifted resonance hyper‐Raman lines. Nearly coinciding resonance hyper‐Raman and one‐photon resonance Raman spectra indicate conditions of A‐term resonance Raman scattering. Second‐order scattering is distinguished from transient anti‐Stokes Raman scattering of v = 1 to v = 0 transitions and v = 1 to v′ = 1 combination transitions by taking into account their different spectral and temporal behaviour. Separating these processes is essential for a proper analysis of transient vibrational populations. Copyright © 2007 John Wiley & Sons, Ltd.     

反斯托克斯拉曼光谱在BaTiO_3铁电相变研究中的应用

从理论上讨论了一阶和二阶斯托克斯与反斯托克斯拉曼散射截面的温度依赖关系;在２９３Ｋ至４０１Ｋ的温度范围内,测量了ＢａＴｉＯ３单晶斯托克斯和反斯托克斯过程的偏振拉曼光谱;通过对ＢａＴｉＯ３单晶斯托克斯和反斯托克斯拉曼光谱的综合分析,证实在Ｘ（ＺＺ）Ｙ几何配置下测量到的位于２７５和５１４ｃｍ－１处的强峰为一阶拉曼光谱。此结果支持了ＢａＴｉＯ３铁电相变机制的有序—无序模型。     

Determination of zone-boundary magnon energy and damping in RbMnF3 by means of light scattering experiments

New experimental data of two-magnon Raman scattering on the cubic antiferromagnet RbMnF₃ are used to obtain information on the single spin dynamics in all the ordered phase. The comparisons with the existing second order theory and with the neutron scattering data shows that the light scattering gives correct values for energy and lifetime of the zone boundary magnetic excitations.     

强激光照射下,α-LiIO3晶体中晶格振动的多模激发和模之间的相互作用

本文叙述了用调Q倍频YAG脉冲激光照射α-LiIO₃晶体,在不同的散射配置下,获得了各种散射谱图。实验表明,当用e光入射时,可以比用o光入射激发起更多不同模的晶格振动;获得了E₂模的很强的一阶、二阶斯托克斯散射线和反斯托克斯散射线,E₁模Polariton的一阶、二阶、三阶斯托克斯线和反斯托克斯线,还获得了反斯托克斯频率区一条频移为469cm^-1的新线,认为是不同模的Polariton之间的相互作用引起的。最后,提到实验中初步观察到的晶体拉曼活性的“疲劳现象”。 关键词：     

Pressure dependence of the impurity soft modes in Li and Na : KTaO3

Low energy Raman scattering measurements on samples of K_0.76Na_0.24TaO₃, K_0.9Na_0.1TaO₃ and K_0.75Li_0.25TaO₃ under hydrostatic pressures of up to 60 kbar supply confirming evidence to the hypothesis that the Na⁺ ions in these crystals are displaced from the centers of the sites they occupy. The pressure Raman experiments also reveal another second order Raman line interpreted as Raman scattering by two TA phonons at M. A line induced by the substitution of Na for K is found to have an energy about equal to the energy of this new second order Raman line. It is shown that if this is a resonant mode it must be an even mode.     

Pressure dependence of phonon energies at critical points in the Brillouin zone in KTaO3 measured with differential second order raman scattering

Wavelength modulated Raman scattering was used to study the effects of pressure on the second order spectrum of KTaO₃. The pressure results lend support to previous identifications of structures in the second order differential Raman spectrum in terms of pairs of phonons from critical points in the Brillouin zone. Using these identification mode Grüneisen parameters are obtained for several vibrational modes. Strong anharmonic behavior of of the TA(X) mode is observed when we correlate the results from pressure measurements with previous studies of the effects of temperature.     

On stability of Raman and degenerate hyper-Raman scattering

The problem of the stationary generation by Raman and degenerate hyper-Raman scattering is solved by means of two methods: stationary solution of the generalized Fokker-Planck equation and linear analysis of stability of the Langevin equations. The conditions of stability and the corresponding stationary values for amplitudes of the Stokes, anti-Stokes or output laser modes are obtained for particular cases. A phenomenon analogous to the second order phase transition can occur for Stokes or anti-Stokes interaction of Raman scattering above the threshold value of the pump amplitude. The anti-Stokes interaction of degenerate hyper-Raman scattering can show bistable behaviour above the second threshold value of the pump amplitude.The author would like to express his sincere thanks to Dr. J. Peina for comments and stimulating discussions.     

LDS751染料的受激喇曼散射

报道了用532nm激光抽运LDS751染料产生720—780nm可调谐染料激光输出的同时,观察到喇曼频移为102和45cm-1的反斯托克斯线,前者谱线较强,后者较弱.与这两条强线对应的斯托克斯线未能观察到.另外,还观察到喇曼频移为34cm-1的一级和二级斯托克斯线与反斯托克斯线 关键词： LDS751染料 受激喇曼散射 喇曼位移 斯托克斯线 反斯托克斯线     

Stimulated Raman scattering in light and heavy water under picosecond laser excitation

The spectra of stimulated Raman scattering in ordinary and heavy water under excitation by second harmonic of a picosecond Nd:YAG laser were compared. It was shown that when stimulated Raman scattering is excited in water in cavities of a photonic crystal (synthetic opal matrix constructed of silica nanoglobules) or a photonic glass in the form of close-packed monodimensional millimeter-size amorphous-quartz balls, the efficiency of stimulated Raman scattering increases significantly compared to a uniform liquid medium.     

Raman spectroscopy of carbon nanotubes

The use of Raman spectroscopy to reveal the remarkable structure and the unusual electronic and phonon properties of single wall carbon nanotubes (SWNTs) is reviewed comprehensively. The various types of Raman scattering processes relevant to carbon nanotubes are reviewed, and the theoretical foundations for these topics are presented. The most common experimental techniques used to probe carbon nanotubes are summarized, followed by a review of the novel experimental findings for each of the features in the first order and second order Raman spectra for single wall carbon nanotubes. These results are presented and discussed in connection with theoretical considerations. Raman spectra for bundles of SWNTs, for SWNTs surrounded by various common wrapping agents, and for isolated SWNTs at the single nanotube level are reviewed. Some of the current research challenges facing the field are briefly summarized.     

Second order resonance Raman scattering in As2S3 glass

First and second order resonance enhanced Raman scattering has been observed for As₂S₃ glass. First order scattering is dominated by a peak at 340 cm^-1 due to the symmetric stretch of the AsS₃ pyramidal group. Two partially resolved second order peaks are observed at about 630 and 710 cm^-1 whose relative intensities are highly temperature dependent and which are due respectively to overtones of the antisymmetric and symmetric AsS₃ stretching modes.     

受激拉曼散射中的二阶量子关联

利用全量子理论和多模受激拉曼散射模型，研究了拉曼放大中，考虑泵浦光耗散时，斯托克斯光和泵浦光二阶量子关联函数随相互作用距离变化的特性，在不计及色散的影响时，斯托克斯光和泵浦光的二阶量子关联函数的变化主要取决于输入斯托克斯光和泵浦光的光强比，在极限情况下，本文的计算结果与拉曼产生的计算结果和经典耦合波理论的计算结果相符合。     

Numerical optimization of the extracavity Raman laser with barium nitrate crystal

The radiation transfer equations of the extracavity Raman laser including up to the third Stokes beams and backward Raman scattering terms were deduced in detail from the wave equation and material equations of stimulated Raman scattering. The radiation transfer equations were solved numerically to optimize the performance of the extracavity Raman lasers with barium nitrate crystal as the nonlinear medium. The optimum reflectivity of the output coupler at the first Stokes was figured out numerically to achieve the maximum conversion efficiency of the first Stokes, and found to be closely related to the pump pulse duration, peak intensity of the pump pulse, and Raman crystal length. With the resonator mirrors highly reflective at the first Stokes, the highest conversion efficiency of the second Stokes was obtained when the input mirror was highly reflective at second Stokes, whereas the output coupler was highly transmissive at the second Stokes. It was found that too high intracavity intensity of the second Stokes would impede the efficient energy extraction from the pump pulse to the first Stokes, and consequently, limit the conversion efficiency of the second Stokes.