基于D2O的光抽运腔式太赫兹波激光谱线竞争

从半经典密度矩阵理论出发,建立了光抽运太赫兹波谱线竞争的双三能级分子系统模型,理论推导了抽运信号吸收系数以及太赫兹波信号增益系数的数学表达式,采用迭代法数值计算了CO2激光-9P(32)抽运重水(D2O)气体分子腔式太赫兹激光66μm和116μm两条谱线之间的竞争。给出了抽运功率、工作气压及激光腔长等工作条件下谱线竞争的一般规律。     

光泵腔式远红外激光器的工作参数研究

在研究光泵腔式NH3分子远红外激光频谱特性的基础上,应用量子系统的密度矩阵理论,采用迭代法和增益迭加原理计算了以TEA CO2－10R（8）泵浦的NH3分子腔式远红外激光器的最佳工作参数。提供了光泵腔式NH3分子远红外激光器（腔式NH3－OPFIRL）的工作参数之间的关系曲线。     

Laser Line Competition in Optically Pumped D2O THz Laser

Based on the theory of semi-classical density matrix and a model of double three-energy-level (DTEL) system for laser line competition in optically pumped D₂O super-radiant terahertz laser (THz Laser), the mathematical expressions of gain coefficients for pumping signal and THz laser signal are deduced, and the competition between 66?μm and 116?μm laser lines is calculated numerically by means of iteration method. The effects of the operation conditions (including pump power, working gas pressure and the length of cavity) on the competition are analyzed. It is found that 66?μm emission dominated the competition; with the increase of working gas pressure (or the cavity length), the spectrum of 66?μm emission experiences changes from discrete double-peak structure to overlapped double-peak structure and finally to a wide-band structure, and the optimum gas pressure varied conversely with the optimum length of the TH_Z laser cavity.     

Study of Lasing Action in a Pulsed Optically Pumped D<Subscript>2</Subscript>O Gas Terahertz Laser

A modified three-level laser kinetics model for a pulsed high-power optically pumped gas terahertz laser is introduced and used to model the lasing kinetics process of a gas terahertz laser system. We, for the first time to our knowledge, investigated the time evolution dynamics process of the pump intensity, population distribution among the energy levels, pump and THz signal gain coefficient, and the THz laser intensity within the pulsed D₂O gas THz laser. High-power THz pulse with peak power of about 7.4 kW and pulse width of 145 ns at wavelength of 385 μm were obtained in the simulation, using an incident pump pulse with peak power of 2.2 MW and pulse width of 110 ns. THz pulse delay of 40 ns and pulse broadening of 35 ns were quantitatively analyzed. In addition, the experimental results for the pulse profile, pulse width, pulse broadening, pulse energy, and peak power are in agreement with the theoretical simulation results.     

Effects of Buffer Gas on Spectra of Optically Pumped Far-Infrared Cavity Laser

By developing a mechanism model of buffer gas, the comprehensive relaxation time of laser operation substance was calculated. By means of solving the density matrix equations, the effects of buffer gas N₂ on the spectrum characteristics of NH₃ FIR laser line with buffer gas N₂ were studied. It was found that by adding proper buffer gas, FIR laser output power could be increased, and spectra widened because of the molecular collision. This work made it possible to develop high output and wide range tunable FIRL.     

缓冲气体对光抽运远红外激光器频谱特性的影响

基于分子振动弛豫理论完善了缓冲气体的作用模型，利用半经典密度矩阵理论与量子力学理论，定量分析研究了缓冲气体对小型光抽运远红外激光过程的作用机理以及缓冲气体作用下小型腔式光抽运NH3分子远红外激光器的频谱特性，讨论了工作气压、抽运功率等工作参数对频谱特性的影响，并对理论计算结果进行了实验验证．二者符合得较好。研究结果表明，在小型光抽运远红外激光器中加入适当的缓冲气体，大量工作气体分子与缓冲气体分子之间的无规碰撞会引起谱线加宽，而且可以使远红外激光输出信号增强。     

Effects of Buffer Gas on the Output of Optically Pumped NH3 Far-Infrared Cavity Laser

By solving the semi-classical density matrix equations and developing a buffer gas mechanism model, the effects of buffer gas on the output power of optically pumped NH₃ far-infrared cavity laser were calculated and verified by experiment. Our results showed that: the output power of NH₃ far-infrared laser could be increased when certain buffer gas was added into the laser medium, and there existed an optimum ratio of gases mixture and an optimum operating gas pressure which could make the output power of far-infrared laser reach maximum.     

光泵腔式NH3分子亚毫米波激光的调谐特性研究

通过求解量子系统的密度矩阵方程,计算了不同管长和不同输入输出功率反射系数的光泵腔式激光器对281um和90.4um的亚毫米波信号的调谐特性,给出了其调谐特性随信号波长λ,激光管长l和功率反射系数R的变化关系。     

Experimental Study of Pulsed Optically Pumped Superradiant and Cavity NH3 Far-Infrared Laser

Using a grating tuned TEA-CO2 laser with 10R(8) and 9R(16) line to pumped superradiant NH3 far-infrared (FIR) laser which operated in the mode of amplified stimulated emission and Fabry-Perot cavity NH3 FIR laser with a sample tube of 100cm and 20cm in length respectively, the corresponding pulsed FIR lasers were obtained successfully. Meantime, the experimental measure method was improved. Besides, the operating performance and the spectral characteristics of superradiant and cavity NH3-OPFIRL were studied experimentally.     

High Efficient, Intense and Compact Pulsed D2O Terahertz Laser Pumped With a TEA CO2 Laser

A high efficient, intense and compact pulsed D₂O terahertz laser is presented, which is pumped by a multi-transverse mode TEA CO₂ laser. For D₂O gas as the active medium, with the cavity length of 120 cm, pulse energy of the THz laser has been investigated as the variation of pump energy and gas pressure. When the pump energy was 1.41 J, the maximum single pulse energy of 6.2 mJ was achieved at the wavelength of 385 μm. Photon conversion efficiency as high as 36.5% was obtained when laser operated at the maximum output energy. As the pump energy was raised from 0.57 to 1.41 J, the optimum pressure was slightly changed from 400 to 700 Pa. The THz pulse consisted of a spike pulse with pulse width of 120 ns and a tail pulse with pulse width of about 170 ns. The peak power of the spike pulse is about 44.3 kW. Comparing with the occurring time and pulse width of pump pulse, 70 ns delay and 10ns broadening were observed in the THz spike pulse.     

Operating Parameter Comparison of Pulsed Optically Pumped NH3 and CH3OH F-P Cavity Far-Infrared Laser

Based on the density matrix theory of quantum system, the optimum operating parameters of pulsed optically pumped NH3 and CH3OH F-P cavity far-infrared laser (NH3/CH3OH-OPFIRL) were studied and compared theoretically. The differences of the operating parameters between the NH3-OPFIRL and CH3OH-OPFIRL were found and discussed. Experimentally, the curves of output power verses gas pressure in NH3 and CH3OH F-P cavity lasers pumped by TEA-CO2 laser were measured, and the optimum operating gas pressure were obtained. The experimental results were in agreement with theoretical calculations.     

The Optimum Coupling Coefficient of Optically Pumped NH3 Far-Infrared Cavity Laser

Based on the semiclassical density matrix theory, the optimum output power reflection coefficient (coupling coefficient) of output coupler for optically pumped NH₃ far-infrared (FIR) cavity laser was calculated by means of iteration method. Experimentally, FIR Fabry-Perot cavity laser was designed and constructed by using inductive metallic meshes as couplers, and the measurement showed that the theoretical calculation were in agreement with experimental results.     

缓冲气体对超辐射光抽运远红外激光器的影响

以NH3作为远红外激光的工作气体 ,以N2 作为缓冲气体 ,对加入缓冲气体前后的小型超辐射光抽运远红外激光器作理论比较研究。基于缓冲气体作用机理模型 ,计算出激光工作物质的综合弛豫时间 ;通过解半经典的密度矩阵方程 ,计算出远红外激光输出的频谱特性和工作气压。计算表明 ,加入缓冲气体后 ,远红外激光的输出得到提高 ;存在一个最佳混合气体比例 ,在这一比例下远红外激光输出达到最大 ;加入缓冲气体后 ,最佳工作气压比加入缓冲气体前获得提高。     

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.     

Operating Parameters Optimization of Miniature Optically Pumped Cavity NH3 Submillimeter Wave Laser

By means of the iteration method, the output power density of the miniature optically pumped NH₃ submillimeter wave (SMMW) laser was calculated based on the density matrix equations of a quantum system. Optimization of operating parameters including operating gas pressure, reflection coefficients of input and output meshes of the laser were studied systematically. In the paper, the concepts of the average activated length and the synthetical optimum value were defined, and some rules of the optimization were explained successfully. Experimentally, a cavity NH₃ SMMW laser that was composed of a pair of inductive metallic meshes and pumped by TEA-CO₂ 10R(8) line was used. The experimental results were in good agreement with our theoretical calculations.     

Effect of Multi-Mode Optically Pumped Far-Infrared Laser Cavity on Spectra and Multi-Raman Interaction

Based on semi-classical density matrix theory, the spectral characteristics and multi-Raman interaction of multi-longitudinal-mode CO₂-9R(30) optically pumped cavity NH₃ molecules 67.2 μ m far-infrared laser were theoretically studied. And with different parameters such as input and output reflection coefficient, length of tube and so on, the rules of multi-Raman interaction and effect on longitudinal structure of 67.2 μ m far-infrared laser spectrum were also discussed theoretically.     

光泵浦垂直外腔面发射激光器斜率效率的分析

研究了光泵浦垂直外腔面发射激光器(OPS-VECSEL)的湿法腐蚀工艺,采用快速腐蚀和精细选择腐蚀相结合的腐蚀方法,使得衬底能被干净地腐蚀掉,并精确停留在阻挡层,得到高平整度的外延片表面,提高了泵浦效率,降低了散射损耗。从理论上分析了外延片表面粗糙度与OPS-VECSEL斜率效率的关系,得出如果在外延片上镀一层λ/4单介质增透膜,能进一步提高VECSEL的斜率效率。     

Operating Parameters Optimization of Buffer Gas in Optically Pumped Submillimeter Wave Laser

Based on the basic theory of molecular vibration relaxation and semi-classical density matrix theory, operating parameters optimization of buffer gas in the process of miniature pulsed optically pumped submillimeter wave laser was systemically studied and the theoretical calculated result was tested by experiments. The result would do favor to develop and study high-power and wide-range tunable miniature and high-efficient pulsed optically pumped submillimeter wave laser and also had some instruction to its application.     

Theoretical Study on NH3 Superradiant Miniature Optically Pumped Far-Infrared Laser with Buffer Gas

A miniature superradiant NH₃ optically pumped far-infrared laser (OPFIRL) with buffer gas N₂ was theoretically studied. Base on the mechanism model of buffer gas, synthetical relaxation time was calculated. By solving the semi-classic density matrix equations, spectra of NH₃ superradiant OPFIRL with buffer gas N₂ was calculated, also the operating gas pressure. It was found that by adding buffer gas, FIR power could be raised, and there existed an optimum ratio of gases mixture and an optimum operating gas pressure which was higher than that of pure NH₃ operating.     

横向光泵获得S_2紫外激光

用ＸｅＣｌ准分于激光器（３０８．１ｎｍ）横向泵浦Ｓ２激光器，又成功地实现了Ｓ２Ｂ－Ｘ态近ＵＶ波段的激光振荡。在波长３３０．９～３９０．０ｎｍ范围内观测到６条近ＵＶ激光输出。测量了有关的激光参数。