光泵NH3分子远红外激光AC Stark分裂频谱研究

以ＮＨ３分子作为工作物质，在ＣＯ２－１０Ｒ（６）泵浦下，利用密度矩阵方程和迭械法计算了ＮＨ３分子的Ｖ２：α→ｓ（５，４）远红外跃迁的频谱特性。理论计算表明，在一定泵浦强度下出现ＡＣ Ｓｔａｒｋ分裂，且ＮＨ３分子工作压强对ＡＣ Ｓａｒｋ分裂不同的影响，当压强达到某一临界值时，ＡＣ Ｓｔａｒｋ分裂的偏频Ｒａｍａｎ峰消失，另外，一定长度的超辐射远红外激光器的输出光强主要受工作气压和砂浦强度的影响，其中     

光泵NH3分子远红外激光研究

运用量子系统的密度矩阵理论，采用迭代法计算了光泵ＮＨ３分子远红外超辐射和腔式激光的频谱特性和相应的最佳工作气压。理论计算表明相对于超辐射方式，光泵腔式ＮＨ３分子远红外激光具有宽带辐射以及纵向调谐特性，且总的输出光强在一定条件下得到提高，最佳工作气压也较低。在实验上对ＴＥＡＣＯ２－１０Ｒ（８）和９Ｒ（１６）泵浦的Ｎ 红外超辐射和腔式激光器产生的远红外辐射进行了测量。结果表明理论计算与实验结果相符。     

光泵远红外分子激光的多光子过程

本文在过去工作的基础上,研究六能级系统在10MW/cm~2功率泵浦下CH_3F分子气体的多光子过程.文中提出了多光子共振图,从而可预示系统中各类多光子过程以及在x-y平面远红外频率随光泵频率变化的轨迹轮廓.理论计算揭示了三光子共振过程对系统增益的贡献,表明在一般情况下,三光子过程具有很小的增益值,而在某些特定频率下,却具有可观的增益,但调谐范围很窄.此外,还讨论了多光子过程之问的相互作用,这些作用除将影响远红外激光的调谐特性外,还存在互相抑制和互相增强的效应.     

光泵远红外激光中的偏频泵交流斯塔克效应

本文研究在六能级系统中的R_(35),T_(34)和S_(54)过程的相互作用.本文从理论研究中发现在偏频泵作用下,这些多光子过程的相互作用也会导致激光谱线的分裂.这就是偏频泵交流斯塔克(AC Stark)效应.这三个过程都受到饱和效应和电偶极增强效应的影响,但其效果各不相同.利用这一特点,可以通过注入远红外信号以区分各过程对系统增益和偏频泵交流斯塔克效应的贡献.     

小型光泵NH_3分子远红外激光器的模式竞争

通过求解四能级系统的半经典密度矩阵方程，用迭代法计算了ＣＯ２－１０Ｒ（６）泵浦小型超辐射光泵ＮＨ３分子远红外激光器（ｍｉｎｉ－ＮＨ３－ＯＰＦＩＲＬ）的Ｐ支和Ｑ支跃迁输出光强的增量比。计算表明在超辐射小型ＮＨ３光泵远红外激光器中，Ｖ２ａ→ｓＰ（５，４）和ａ→ｓＱ（５，４）模式竞争结果，Ｑ支跃迁占优势，使Ｐ支被抑制。理论计算与实验结果一致     

光泵远红外激光器中的光束匹配

本文对CO_2激光束与开式腔远红外激光器的匹配问题进行了分析,给出了远红外工作物质对CO_2激光的吸收率与耦合孔逸出损失之间的定量关系,指出对确定的远红外共振腔有一最佳的匹配发散角。在该角度下,工作物质有最大的激活体积,并可获得较高的远红外激光输出。     

刚性对称陀螺分子Stark效应的精确解

提出了一种精确求解位于外电场中刚性对称陀螺分子转动能级和相应解析波函数的新方法.首先利用不同形式的函数变换和变量代换将位于外电场中对称陀螺分子的极角θ方向的方程转化为合流Heun微分方程,然后根据合流Heun微分方程和合流Heun函数具有的特点,找到描述同一本征态的线性相关的两个解,构造Wronskian(朗斯基)行列...     

超辐射式和腔式光泵氨分子 远红外激光特性比较

在对超辐射式和腔式光泵NH3分子远红外激光(NH3-OPFIRL)进行系统 深入地理论和实验研究的基础上,对这两类激光器的结构、特点、频谱特性及最佳工作参数 的差异进行了分析和比较,并给出了一系列有重要参考价值的理论结果和实验数据。     

光泵腔式NH3分子远红外激光的最佳工作气压研究

通过求解量子系统的密度矩阵方程，采用迭代法计算了光泵腔式ＮＨ３分子远红外激光的输出功率密度。在此基础上，对光泵腔式远红外激光的工作气压进行了理论研究。结果表明最佳工作气压与腔的功率反射系数、样品管的长度以及泵功率密度等工作参数之间是相互制约的，同时与参与激光过程的能级有关。在实验上采用电感性金属栅网作为反射器，设计制作出长度分别为１００ｃｍ、２０ｃｍ和１０ｃｍ的Ｆａｂｒｙ－Ｐｅｒｏｔ腔式远红外激光器，然后和ＴＥＡ－ＣＯ２激光器作泵浦源，成功地获得光泵ＮＨ３分子远红外激光，测量结果表明理论计算与实验数据相符。     

量子场作用下二能级原子的AC Stark效应

计算了处在粒子数态的单模量子场与二级原子相互作用时能级ＡＣ Ｓｔａｒｋ移动,平均能级移动值随场模波频变变化呈色散线型,随场模中光子数的增加会逐渐达到饱和。另外,还发现即使是场模中光子数为零,量子场仍能通过ＡＣ Ｓｔａｒｋ效应使原子能级发生移动。     

Theoretical Study of Optically Pumped NH3 Far-Infrared Laser in Vibrational Ground State

In this paper, the density matrix equation of three-level system for far-infrared (FIR) Raman transition in vibrational ground state was solved. By means of iteration method and numerical calculation, the spectral characteristics of NH₃ molecules FIR laser with TEA CO₂-10R(14) laser pumping was studied theoretically. The theoretical result would help us to understand the physical mechanism of optically pumped molecular gases FIR laser with ground-state reversal transition.     

Study on Stark Effect in Optically Pumped Far-Infrared Laser

The output intensity of optically pumped NH3 molecules far-infrared laser (NH3-OPFIRL) was calculated by solving the density matrix equation and by means of iteration method. Meanwhile, the spectral characteristic of AC Stark splitting was studied. Finally, the F-P interferogram of NH3-OPFIRL pumped by CO2-10R(8) line was measured. The experimental results were in good agreement with the theoretical calculation results.     

Spectral Characteristics of Miniature Two-Longitudinal-Mode Optically Pumped FIR Laser

With the assumption that the pump source was two-longitudinal-mode, the semiclassical density matrix equation of a three-energy-level system was solved. By means of iteration method, the spectral characteristics of miniature two-longitudinal-mode optically pumped NH₃ far-infrared cavity laser, which was pumped by CO₂-9R(16) line, were calculated numerically. The influences of operating parameters on laser spectrum were studied intensively.     

Rotational Spectrum of the Excited Vibrational States of DCOOH and Assignment of Optically Pumped Laser Transitions

The rotational spectrum of DCOOH in the 175–335 GHz region was investigated. Analysis of the spectrum made it possible to assign several dozen transitions in the ν₆, ν₈, and ν₅vibrational states and to determine the rotational and centrifugal distortion constants. The derived parameters of the ν₆state allowed four optically pumped laser transitions to be assigned. In addition, the ground state parameters for DCOOH and D¹³COOH have been improved and for the first time those for DC¹⁸OOH and DCO¹⁸OH have been obtained.     

Theoretical Study of Optimum Operation of Two-Longitudinal-Mode Optically Pumped Miniature FIR Laser

Based on the semi-classical density matrix equation, the optimum operation of two-longitudinal-mode optically pumped miniature FIR laser was studied theoretically. The relations and the contributions to FIR laser output power of the laser structural parameters and operating parameters were calculated and discussed.     

Spectroscopy of Methanol and Its Application to Optically Pumped THz FIR Lasers

In this paper, we have reviewed the details of experimental and theoretical aspects of the high-resolution molecular spectroscopy of methanol isotopomers. The methods of spectroscopic assignments and analysis have been discussed. The applications of the spectroscopic techniques, particularly of Fourier transform spectroscopy in the field of optically pumped Terra-Hertz Lasers (OPTL) and far infrared (OPFIR) lasers have been discussed. New assignments have been deduced for TEA-CO₂ laser pumped methanol and CW CO₂ pumped ¹³CD₃OD. Stark effect analyses and the determination of accurate dipole moment values have been discussed for CH₃OH, ¹³CH₃OH and CH₃ ¹⁸0H. The importance of high-resolution spectroscopy is also discussed in terms of astrophysical detection. Some recent ongoing astrophysical efforts are outlined. In our laboratory we are in the process of setting up a THz methanol laser for astrophysical applications and search for new coherent monochromatic laser sources.     

Spike Phenomenon in Raman Spectrum of Optically Pumped Ear-Infrared Laser

Based on the theory of semi-classical density matrix, spike phenomenon of multi-longitudinal-mode CO2-9R(30) optically pumped miniature NH₃ molecules far-infrared cavity laser was theoretically studied and the reason of forming spike phenomenon was approved as two aspects: one was the competitive effect caused by the process of AC Stack splitting two photons, which made that the output optical spectral intensity of one AC Stark splitting peak was stronger than that of the other AC Stark splitting peak; the other was the longitudinal-mode spectral characteristics of laser resonant cavity.     

Relaxation Processes at High Levels of Vibrational Excitation of Polyatomic Molecules in the Ground Electronic State

By the spectral and kinetic characteristics of the luminescence of vapors of polyatomic molecules (anthracene, anthraquinone, fluorenone) initiated by selective IR multiphoton excitation (IR MPE) of molecules in the ground electronic state S ₀ the relaxation processes proceeding under vibrational excitation of molecules to energies exceeding the energies of the lower excited electronic states have been investigated. The changes in the spectral and kinetic characteristics with increasing CO₂ laser energy density and vapor P _v and foreign gas pressure P _FG are analyzed. They are similar to the characteristics obtained for normal fluorescence of these molecules with changing vibrational energy E _vib content. On the basis of experimental data and model calculations it has been concluded that at the laser radiation densities used in the case of IR MPE the molecules reach energies considerably exceeding the energies of the electronic levels. It is shown that a nonadiabatic connection between the electronic states leads to the population of mixed electronic states isoenergetic to the vibrational levels of the ground electronic state and to emission of delayed luminescence spectrally identical to the normal luminescence of these molecules. It has been found that when high vibrational levels are populated, new relaxation channels, such as reverse electron relaxation, emission from high vibrational levels of the ground electronic state, and multiquantum vibrational energy transfer at collisions leading to a rapid establishment of vibrational equilibrium become important.     

Temperature and Mass Factor of Buffer Gas Effect in Optically Pumped Submillimeter Wave Laser

Based on semi-classical density matrix theory and SSH theory, the effect of buffer gas in optically pumped submillimeter wave laser was theoretically studied and the effect of temperature and mass on the effect of buffer gas was analyzed, then the selection rules of buffer gas were achieved. The results could do favor to find high-efficient buffer gas of miniature optically pumped submillimeter wave laser and also had some instruction to its application.