Stimulated resonance Raman scattering

A quantum mechanical theory of stimulated resonance Raman scattering taking full account of the effects of the incident and scattered radiation on the state and properties of the molecules is developed. The resulting formulas enable the amplification of the scattered radiation and the attenuation of the incident flux to be determined. The conditions under which stimulated Raman scattering produces amplification of radiation are formulated. The range of applicability of the theory, not taking account of the effects of radiation on the properties of the material is discussed.     

Stimulated Raman scattering of pre-gaussian light

The quantum theory of a forward Stokes generation by means of stimulated Raman scattering is considered in the case of a pre-gaussian pump composed by two and three telegraphs. As for the case of a colored chaotic pump the mean Stokes intensity is found to be enhanced over that resulting from a coherent pump in both transient and steady-state limits. In the limit that the pre-gaussian bandwidth becomes large, the mean Stokes intensity also becomes identical with that resulting from a coherent pump.     

Stimulated Raman scattering and spontaneous Raman solitons in ammonia

In this study we report the first observation of spontaneous Raman solitons in stimulated Raman scattering (SRS) by the gas NH₃. The scattered radiation is called Stokes radiation. Raman solitons are of considerable interest, because their existence can be explained by quantum-mechanical fluctuations of the electromagnetic field in vacuum. We have observed spontaneous Raman solitons in a forward SRS configuration for two different molecular transitions of NH₃, the laser emissions at 58 μm and 72.6 μm wavelength. These are optically pumped by 10 μm CO₂-laser pulses with a duration of 100 ns and an energy of 150 mJ. Spontaneous Raman solitons are short spikes in the pump pulse which occur during its depletion. Their origin is the rapid π phase change of the Stokes seed. In contrast to other laboratories we have used single-pass cells. Thus, we have succeeded in observing multiple spontaneous Raman solitons during one pump pulse. Previous experiments with multi-pass cells never showed multiple solitons. Since multiple spontaneous Raman solitons have already been reported in an earlier experiment with a single-pass cell filled with hydrogen at high pressure, we conclude that such multiple Raman solitons can be observed mainly in this type of gas cell. Subsequently, we have performed statistical measurements on the delay time and the height of the spontaneous Raman solitons in the depleted pump pulse for the 58 μm-NH₃ emission. We have compared these statistics with theory and equivalent experimental results of other laboratories. They are in good agreement with the assumption that quantum-mechanical fluctuations are the origin of spontaneous Raman solitons. The most recent theories postulate that the origin of the formation of spontaneous Raman solitons can be explained by the rapid π phase change of the Stokes seed as well as that of the laser or polarization wave. Therefore, we have determined the phase of the spontaneous Raman solitons relative to the depleted pump pulse. Although, such changes of sign of the relative phase have already been observed in an earlier SRS experiment with hydrogen at high pressure, we did not detect any in our experiment. Therefore, we conclude that in this experiment the π phase change occurs in the Stokes or polarization wave.     

Stimulated electronic Raman scattering in In vapor

High power density electron beams offer new opportunities for studies of epitaxial growth of semiconductor materials. Assuming that the mechanism of epitaxial growth can be understood as a surface melting followed by supercooling regrowth, the heat flow equation has been applied to calculate the temperature reached after an electron beam pulse of power density between 0.5–2 J/cm². Comparison with laser annealing is made.     

Stimulated electronic Raman scattering in potassium vapour

A tunable stimulated electronic Raman scattering, involving the 4S → 3D transition, is generated with a pulsed dye-laser focussed in potassium vapour. Some properties of the infrared emission such as tuning range, nature of the final sublevel (3D_{$\text{5}\text{2}$} or 3D_{$\text{3}\text{2}$}), Raman wave polarization direction, are described.     

Stimulated Raman scattering in three-dimensional photonic crystals

The results of experimental studies of stimulated Raman scattering of light (SRS) excited in three-dimensional photonic crystals — synthetic opal matrices infiltrated with Raman active media are presented. It is shown that the SRS threshold in such structures decreases with respect to the SRS threshold in Raman active bulk materials. The influence of the photonic-band structure of the active materials used on the SRS properties is estimated.     

KDP晶体受激拉曼散射特性

详细比较了磷酸二氢钾(KDP)晶体的自发拉曼散射和受激拉曼散射光谱,在受激拉曼散射(SRS)中观察到了自发拉曼散射中最强的振动模的三阶Stokes 光(559.43, 589.74, 623.50 nm),由于其他振动模的受激拉曼散射增益系数较小,其SRS光谱未观察到。另外,比较了传统生长的未退火和退火后的KDP晶体及快速生长的锥区和柱区KDP晶体的受激拉曼散射增益系数,结果表明生长方法和热退火对KDP晶体的受激拉曼散射增益系数无明显影响。     

LiIO3晶体的受激拉曼散射

 采用腔外单次通过方式,测量了LiIO₃晶体在532 nm皮秒脉冲下的受激拉曼散射。实验中观察到3级斯托克斯线（556.07,582.30, 611.76 nm）和1级反斯托克斯线（509.57 nm）,由此可计算出其频率间隔为820 cm^-1。测量了LiIO₃晶体各级拉曼散射谱线的阈值和增益系数,受激拉曼散射的整体转换效率达到56%。基于LiIO₃晶体实现了皮秒外腔式拉曼激光器的运转,双波长输出总转换效率为27%,最大输出能量1.4 mJ。     

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     

KDP晶体受激拉曼散射特性

详细比较了磷酸二氢钾(KDP)晶体的自发拉曼散射和受激拉曼散射光谱,在受激拉曼散射(SRS)中观察到了自发拉曼散射中最强的振动模的三阶Stokes光(559.43,589.74,623.50nm),由于其他振动模的受激拉曼散射增益系数较小,其SRS光谱未观察到。另外,比较了传统生长的未退火和退火后的KDP晶体及快速生长的锥区和柱区KDP晶体的受激拉曼散射增益系数,结果表明生长方法和热退火对KDP晶体的受激拉曼散射增益系数无明显影响。     

Stimulated Raman scattering pulses. I. Weak scattering

Rate equations are used to compute a weak stimulated Raman scattering pulse in the case where the scattered radiation energy can be neglected in the over-all energy balance. Expressions for the shape, position and height of the maximum, duration, and spectral width of the scattering pulse as functions of the parameters of the driving laser, scattering material, and observation conditions are derived.     

Stimulated resonance Raman scattering of Rhodamine B

Stimulated resonance Raman scattering (SRRS) of the Rhodamine B (RhB) in the methanol (CH₃OH) or ethanol (C₂H₅OH) solutions have been observed. SRRS from RhB can be distinguished from the amplified spontaneous emission (ASE) of RhB with increasing the input laser energy. When the RhB is dissolved in the methanol or ethanol (10^?3 mol/L), the RhB have the different peak wavelengths of SRRS, ASE, fluorescence and absorption, respectively. SRRS can be amplified by the ASE gain when the SRRS is near the peak of the ASE, and the peak wavelength of SRRS coincides with the maximal intensity wavelength of ASE.     

YbVO4晶体的受激拉曼散射

采用腔外单次通过方式,研究了一种新型晶体YbVO4的受激拉曼散射.当抽运激光为532 nm皮秒脉冲时获得了3级斯托克斯线(558.47 nm,587.92 nm,620.67 nm)和1级反斯托克斯线(507.58 nm),测得YbVO4晶体1级斯托克斯受激拉曼散射的稳态增益系数为17.8 4±O.2 cm/Gw,受激拉曼散射的整体转换效率达到37%.实现了YbVO4晶体对355 nm皮秒激光的受激拉曼散射,观察到1级斯托克斯线(366.11 nm),根据抽运阈值得到相应的拉曼增益为29.0±0.3 cm/GW.     

部分离化激光等离子体的受激喇曼散射不稳定性

由于部分离化激光等离子体中存在束缚电子，它可显著改变其参量不稳定性。本文分析了部分离化激光等离子体的受激喇曼散射的非线性色散关系，计算了钕玻璃倍频和三倍频激光受激喇曼散射的增长率，结果表明，前向受激喇曼散射显著增强，后向受激喇曼散射影响不大。     

氢和甲烷混合气体的受激喇曼散射

使用调Q Nd~(3+):YAG激光的二次谐波(532nm)作为泵浦源,探讨了氢和甲烷混合气体的受激喇曼散射效应。利用光学光谱分析仪(OSA)监测,在不同比例的混合气体中,观测到氢和甲烷各自的SRS谱线以及两种气体的联合谱线,[m,n,=0,|±1,±2,…];观察到斯托克斯和反斯托克斯的谱线频移。实验表明两种气体的混合使得氢和甲烷的受激喇曼散射过程发生了竞争和耦合。     

Stimulated scattering of electromagnetic waves in a magnetised plasma

We present estimates of threshold powers, growth rates and amplification factors for stimulated scattering of electromagnetic waves off electrostatic modes in a magnetized plasma, The magnetic field strength is assumed to influence only the electrostatic modes and not the propagation of incident and scattered electromagnetic waves.     

Stimulated Raman scattering in a relativistic electron oscillation plasma

Received: 27 October 1995/Revised version: 25 September 1996     

CBrCl3液芯光纤中的受激喇曼散射

以1.06μm调Q-锁模激光泵浦CBrCl_3液芯光纤,观察到11级受激喇曼散射,测量了各级受激喇曼散射的相对峰值功率及第9、10和11级的频谱.这种液芯光纤中的受激喇曼散射可作为获得2μm以上波段红外相干光的手段.