共查询到20条相似文献,搜索用时 93 毫秒
1.
强激光长程传输中受激拉曼散射对光束特性的影响 总被引:2,自引:1,他引:1
依照受激拉曼散射(SRS)半经典理论从物质激发感应出的三阶非线性极化率X~(3)出发,在强激光长程传输受激拉曼散射中建立了泵浦(传输)激光相位与斯托克斯(Stokes)光强相耦合的理论模型。它清楚地说明了SRS效应影响泵浦激光光束特性,其中包括时间特性及空间特性(光束质量)的物理机制及影响因素。理论分析与实验结果符合得较好。实验还测得了不同转换效率η_s情况下传输后的泵浦光及Stokes光的时间过程特性。结果表明,在小转换效率的条件下,泵浦光时间特性基本不受SRS效应的影响;而当转换效率η_s>5%时,泵浦光脉宽随η_s增大而被逐渐压缩。 相似文献
2.
3.
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。 相似文献
4.
由于硝酸钡晶体具有很强的对称振动(频率1 047 cm-1)和较高的拉曼增益,可以用来产生受激拉曼激光。采用单端泵浦的外置拉曼振荡腔与双棱镜分光装置进行了硝酸钡晶体拉曼激光实验,泵浦源为倍频Nd: YAG的532 nm激光,硝酸钡晶体通过水溶液降温法生长,尺寸为10 mm×10 mm×48 mm,采用特殊镀膜的腔镜对各阶斯托克斯光进行优化选择。在泵浦源达到65 mJ时,获得21 mJ一阶斯托克斯光,输出波长为563 nm,以及16 mJ的二阶斯托克斯光,输出波长为599 nm,受激拉曼散射SRS最大的整体转换效率(包含一阶、二阶斯托克斯光之和)为56.3%。 相似文献
5.
使用等离子体背向受激拉曼散射对激光进行放大时,等离子体的密度、温度和长度都会对激光的放大效果产生影响.为了探究等离子体密度对结果的影响,本文使用一维粒子模拟程序模拟了波长为800 nm的泵浦激光入射到均匀等离子体中,等离子体密度和泵浦光光强对散射光光谱的影响.模拟结果表明,等离子体密度降低会导致散射光的波长变短,而泵浦光的光强在一定范围内降低会增加散射光中背向散射光的比例.通过分析散射光的光强和等离子体的密度,发现前向拉曼散射是等离子体密度变化的原因.模拟结果对等离子体背向受激拉曼散射放大的实验研究具有重要的指导意义. 相似文献
6.
采用瞬态受激旋转拉曼散射(SRRS)模型,并充分考虑非线性介质分子密度、增益系数、泵浦光的衰减、斯托克斯光的非线性放大以及初始的随机斯托克斯散射场等因素,研究了空气真空度对强紫外激光在空气长程传输过程中产生的SRRS效应的影响。结果表明,真空度对SRRS效应的阈值传输距离和Stokes光的转换效率的影响较大,随着真空度的提高,Stokes光的转换效率将降低,产生SRRS效应的阈值传输距离将增大。因此,在实际工作中,可以采用真空度较高的激光传输环境来抑制SRRS效应的产生,以减小入射泵浦光能量的衰减并提高光束质量。 相似文献
7.
采用瞬态受激旋转拉曼散射(SRRS)和空间相位扰动模型,定量分析了泵浦光强度和脉冲宽度对基频光在空气长程传输过程中产生的SRRS效应的阈值距离和转换效率的影响,讨论了泵浦光空间相位畸变对长程传输后的基频光光束质量的影响。研究结果表明:SRRS效应的阈值距离随着泵浦光强度和脉宽的增大而变短;空间相位畸变对斯托克斯光和泵浦光的光强分布存在一定影响,对斯托克斯光相位分布的影响比对泵浦光相位的影响大;SRRS效应的存在将导致基频光光束质量明显变差,对谐波转换效率产生明显影响。 相似文献
8.
利用瞬态受激旋转拉曼散射(SRRS)模型及相位畸变模型,对具有空间相位畸变的强紫外激光束在空气中长程传输的SRRS效应进行了研究。详细讨论了低频和中高频空间相位畸变对SRRS阈值条件、斯托克斯光转换效率、剩余泵浦光和斯托克斯光相位的影响。研究结果表明,泵浦光的初始相位畸变对斯托克斯光相位畸变的影响较剩余泵浦光的更为明显;高频相位畸变对转换效率影响较低频相位畸变更大; SRRS效应阈值随低频相位畸变的增大而减小,随高频相位畸变的增大而增大。 相似文献
9.
10.
11.
通过研究光参量啁啾脉冲放大过程转换效率随泵浦光啁啾参数的变化,以及信号光和泵浦光波长的对应关系,确立了信号光和泵浦光同步时实现线性啁啾匹配的方法。以磷酸二氢钾作为非线性晶体,研究了信号光和泵浦光之间的线性啁啾匹配和时间同步抖动对光参量啁啾脉冲放大后信号光脉冲波形和转换效率的影响。结果表明:在时间同步的情况下,线性啁啾匹配时的信号光脉冲波形很对称,转换效率也较高;在同步抖动程度一定的情况下,不同泵浦光啁啾参数时,信号光的增益及放大后的脉冲波形差异较大;在线性啁啾匹配程度一定时,信号光和泵浦光时间同步抖动越严重,放大信号光的脉冲波形变化越大,信号光增益越小,且转换效率也越低。 相似文献
12.
Conversion efficiency in optical parametric chirped-pulse amplification is limited by spatiotemporal characteristics of the pump pulse. We have demonstrated a novel hybrid chirped-pulse amplification scheme that uses a single pump pulse and combines optical parametric amplification and laser amplification to achieve high gain, high conversion efficiency, and high prepulse contrast without utilization of electro-optic modulators. We achieved an overall conversion efficiency of 37% from the hybrid amplification system at a center wavelength of 820nm. Generation of multiterawatt pulses is possible by use of this simple method and commercial Q -switched pump lasers. 相似文献
13.
Cascade parametric amplification in a regular domain structure is examined theoretically taking the variations in phase of
all the interacting waves in a dissipative medium into account. Analytic expressions are obtained for the conversion efficiency
of the laser energy with low-frequency pumping. The dependence of the parametric amplification efficiency on the number of
layers is given. Ways of increasing the frequency conversion efficiency are discussed. The presence of a nonzero input intensity
at the sum frequency is found to cause a nonlinear increase in the high-frequency signal at the output of the structure. As
the losses of the interacting waves increase, both the frequency conversion efficiency and the optimum domain length decrease. 相似文献
14.
High-conversion-efficiency, high-stability optical parametric chirped-pulse amplification is demonstrated with a spatiotemporally shaped pump laser system. Broadband 5-mJ pulses are produced at a 5-Hz repetition rate with a pump-to-signal conversion efficiency of 29% and energy stability better than 2% rms. To our knowledge this is the highest conversion efficiency and stability achieved in an optical parametric chirped-pulse amplification system. 相似文献
15.
根据信号波和闲频波所满足的耦合非线性薛定谔方程,导出了双抽运参量放大增益系数g、信号波的放大因子和闲频波转换效率,并在输入总抽运功率不变的情况下,仅改变双抽运功率P1,P2的比值s,对参量放大增益系数g、信号波的放大因子和闲频波转换效率理论研究和数值模拟;数值模拟结果表明:相位匹配条件下,通过改变双抽运功率的比值 ,可获得适当的放大的信号波和一定转换效率的闲频波。 相似文献
16.
根据信号波和闲频波所满足的耦合非线性薛定谔方程,导出了双抽运参量放大增益系数g、信号波的放大因子和闲频波转换效率,并在输入总抽运功率不变的情况下,仅改变双抽运功率P1,P2的比值s,对参量放大增益系数g、信号波的放大因子和闲频波转换效率理论研究和数值模拟;数值模拟结果表明:相位匹配条件下,通过改变双抽运功率的比值 ,可获得适当的放大的信号波和一定转换效率的闲频波。 相似文献
17.
18.
Chekhlov OV Collier JL Ross IN Bates PK Notley M Hernandez-Gomez C Shaikh W Danson CN Neely D Matousek P Hancock S Cardoso L 《Optics letters》2006,31(24):3665-3667
We report on what is believed to be the first large-aperture and high-energy optical parametric chirped pulse amplification system. The system, based on a three-stage amplifier, shows 25% pump-to-signal conversion efficiency and amplification of the full 70 nm width of the seed spectrum. Pulse compression to 84 fs achieved after amplification indicates a potential of 300 TW pulse power for 35 J amplified pulse energy. 相似文献
19.
Nikolov I Gaydardzhiev A Buchvarov I Tzankov P Noack F Petrov V 《Optics letters》2007,32(22):3342-3344
Ultrabroadband parametric amplification of a white-light continuum in the near IR (approximately 100 THz, 1.2-2.4 microm) is demonstrated in BiB3O6 pumped by 45 fs long pulses at 800 nm at a repetition rate of 1 kHz. The energy obtained with a 5 mm thick crystal reached 50 microJ, corresponding to external conversion efficiency of 20%. 相似文献
20.
Alexander I. Vodchits Valentin A. Orlovich Valery P. Kozich 《Optics Communications》2008,281(11):3190-3195
Applying gas recirculation in a high pressure cell, laser pulses of 1 ps at 400 nm and with a repetition rate of 1 kHz were frequency shifted by stimulated Raman scattering and amplification in methane gas at high pressure. We studied the influence of gas recirculation on the conversion efficiencies into the Stokes and anti-Stokes components as well as on their spatial distributions and spectral shapes using generator and generator-amplifier arrangements. For high pump energies, recirculation in the generator cell decreases conversion efficiency into the first Stokes component whereas it increases conversion into higher Stokes and anti-Stokes components. It results in a significantly improved spatial characteristics of the frequency-shifted radiation, however, is accompanied by a substantial spectral broadening. Using gas recirculation in the generator-amplifier arrangement we achieved a conversion efficiency into the first Stokes component of about 50% with highly improved spatial and spectral characteristics. 相似文献