【作者】 李爽；

【导师】 门志伟；

【作者基本信息】 吉林大学 ， 光学， 2022， 硕士

【摘要】 在19世纪中期,二硫化碳（CS₂）首次在工业上用于硫化橡胶时,还只是实验室里的稀世珍品。从那时起,它就有了许多商业用途。目前主要用于生产粘胶、人造丝和玻璃纸,并做为粘合剂和清洁剂的溶剂。与其他液体相比,CS₂的振动弛豫时间相对较慢,可以输入较大的光能密度,从而可以更精密地研究激光诱导击穿机制以及受激拉曼散射过程。我们利用受激拉曼散射技术对二硫化碳受激拉曼短脉冲进行了研究;同时,对二硫化碳和苯的混合溶液中一些非线性光学现象进行探索。本论文取得了以下创新性成果:1.利用波长为532 nm的纳秒脉冲Nd:YAG激光器研究了二硫化碳分子双样品池的级联受激拉曼散射。当泵浦激光能量为1.909 m J时,仅在一个样品池（C₁）中产生4阶斯托克斯和2阶反斯托克斯受激拉曼散射光。然而,当泵浦能量为0.883 m J,在第二个样品池（C₂）中可以获得相同结果。同时,当泵浦能量增加到1.208 m J时,C₂中产生5阶斯托克斯,相干辐射波长范围为498～644nm。结果归因于共振增强效应:泵浦激光与从工作介质（CS₂）发射的斯托克斯光之间的频率差与C=S的振动能级匹配,从而导致产生级联宽带受激拉曼散射。反斯托克斯受激拉曼散射归因于四波混频的结果。同时,斯托克斯和反斯托克斯的脉冲持续时间被压缩到约380 ps。共振效应不仅降低了受激拉曼散射阈值,并且产生了宽带和短脉冲受激拉曼散射。2.研究了二硫化碳和苯的混合溶液在不同温度下的级联受激拉曼散射和四波混频过程。在20℃下,可以显著抑制受激布里渊散射,降低热自散焦效应引起的光束畸变,从而提高受激拉曼散射的能量转换效率。同时,分析了温度对四波混频相位匹配的影响。获得了C=S伸缩振动、CC环骨架呼吸振动和C-H伸缩振动的多阶斯托克斯和反斯托克斯受激拉曼散射,并且还观察到了与C=S伸缩振动和CC环骨架呼吸振动相关的四波混频峰。该研究结果对液体介质中的多波长拉曼激光具有重要意义。同时,该方法提供一种新型的可调超宽相干光源。更多还原

【Abstract】 When carbon disulfide（CS₂）was first used industrially to vulcanize rubber in the mid-19th century,it was a laboratory rarity.Since then,it has had many commercial uses.The main current uses are in the production of viscose,rayon and cellophane,and as a solvent for adhesives and cleaners.Compared with other liquids,CS₂ has relatively slow vibrational relaxation times and can input a larger optical energy density,allowing a more detailed study of the laser-induced breakdown mechanism and the stimulated Raman scattering process.We use the stimulated Raman scattering technique under the action of laser-induced breakdown mechanism to study the short pulse of carbon disulfide.At the same time,some anomalous phenomena in the mixed solution of carbon disulfide and benzene are accurately described by this technique.The following innovative results have been achieved:1.Cascaded Stimulated Raman scattering（SRS）of carbon disulfide（CS₂）was investigated by a pulsed Nd:YAG laser with 532 nm wavelength.The 4 orders Stokes and 2 orders anti-Stokes were generated when the pump laser energy was about 1.909m J in one sample cell（C₁）only;however,the same result was obtained in the second sample cell（C₂）with the 0.883 m J of pump energy.At the same time,the 5^th-order Stokes line was produced in C₂ with the pump energy increasing to 1.208 m J,the coherent radiation wavelength was from 498 to 644 nm.The result was attributed to the resonance enhancement effect,where the frequency difference between the pump laser and the Stokes light emitted from the working medium（CS₂）self-matches with the vibrational energy level of C=S,which resulted in the cascade broadband SRS generated.The anti-Stokes SRS is attributed to the four-wave mixing（FWM）.Simultaneously,the pulse durations of Stokes and anti-Stokes were compressed by SRS and laser-induced breakdown（LIB）.The resonance effect not only reduces the threshold,but also generates the broadband and short pulse SRS.2.Cascade Stimulated Raman scattering（SRS）and four-wave mixing（FWM）of the mixed solution of carbon disulfide and benzene at different temperatures were investigated.At the low temperature,the stimulated Brillouin scattering（SBS）can be significantly suppressed,the beam distortion caused by thermal self-defocusing effect can be reduced,thereby improving the energy conversion efficiency of SRS.Not only the multi-order Stokes and anti-Stokes SRS of C=S stretching vibration,CC ring skeleton vibration and C-H stretching vibration were obtained,but also the 1^st（～583nm）and 2^nd-order（～646 nm）FWM was generated by the Stokes,anti-Stokes lines and pump laser.The results are of great significance for the multi-wavelength Raman laser in liquid medium,and the method can also provide a new kind of tunable coherent light source with the ultra-widened.更多还原