光泵气体THz激光器的能量转化效率的研究

发布时间：2018-04-15 21:45

本文选题：THz波 + NH3　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：THz波位于电磁波谱中微波和红外波之间,属于亚毫米波。由于其性质十分独特,能穿透非金属、非极性材料、烟雾和浮尘等且不造成伤害,并且能够识别生物大分子,因此,研究高能量转化效率的THz源意义重大。本论文从提高光泵气体THz激光器的能量转化效率方面入手,利用TEA CO2激光器作为泵浦源,利用NH3(氨气)气体作为工作介质,从理论和实验方面对能量转化效率随泵浦能量和气体压强的变化规律进行了初步研究。理论方面,建立了三能级速率方程理论模型,采用四阶Rung-Kutta法,利用MATLAB程序进行数值仿真,从激光产生机理的角度分析了泵浦能量和气体压强对各能级粒子数以及THz光子数的影响。在特定气压下,研究了能量转化效率随泵浦能量的变化规律,得到能量转化效率的最大值为0.3%,且在泵浦能量为200m J~1J范围内基本维持不变,在0~200m J以及1~50J,能量转化效率均低于0.3%;在特定泵浦能量下,研究了能量转化效率随气体压强的变化规律,得到能量转化效率最大值处对应的气压为550Pa,并考虑了泵浦光在NH3气体中的吸收过程对气体压强及能量转化效率的影响。实验方面,设计并搭建了光泵NH3气体超辐射THz激光器,测试了泵浦源TEA CO2激光器的性能;研究了TEA CO2激光器的9R(16)支线及其两侧支线9R(14)支线和9R(18)支线在NH3气体中的吸收特性。在特定气压下,研究了能量转化效率随泵浦能量的变化规律,得到了能量转化效率随泵浦能量呈线性增长规律,并且在泵浦能量为200m J时,获得能量转化效率最大值为0.4%;在特定泵浦能量下,研究了能量转化效率随气体压强的变化规律,得到能量转化效率最大值处对应的气压约为550Pa。对比了理论与实验关于能量转化效率的研究,对误差产生的原因进行了分析,并指出了理论模型的优缺点及后续研究的方向。
[Abstract]:THz wave lies between microwave and infrared wave in electromagnetic spectrum and belongs to submillimeter wave.Because of its unique properties, it can penetrate non-metallic, non-polar materials, smoke and floating dust without causing harm, and can recognize biological macromolecules, so it is of great significance to study the THz source with high energy conversion efficiency.In this paper, the energy conversion efficiency of the optically pumped gas THz laser is improved. The TEA CO2 laser is used as the pump source and the NH _ 3 (ammonia) gas as the working medium.The variation of energy conversion efficiency with pump energy and gas pressure is studied theoretically and experimentally.In theory, a theoretical model of three-level rate equation is established, and the four-order Rung-Kutta method is used to carry out numerical simulation by using MATLAB program.The effects of pump energy and gas pressure on the number of particles and THz photons at different levels are analyzed from the point of view of laser generation mechanism.The variation of energy conversion efficiency with pump energy is studied at specific pressure. The maximum energy conversion efficiency is 0.3, and the energy conversion efficiency remains unchanged in the range of 200m J ~ (-1) J.The energy conversion efficiency is lower than 0.3 at 0 ~ 200 MJ and 1 ~ 50 J, and the variation of energy conversion efficiency with gas pressure is studied under the specific pump energy.The pressure corresponding to the maximum energy conversion efficiency is 550 Pa. the influence of the absorption process of pump light in NH3 gas on the gas pressure and energy conversion efficiency is considered.In the aspect of experiment, the optical pump NH3 gas superradiance THz laser is designed and constructed, the performance of the pump source TEA CO2 laser is tested, and the absorption characteristics of the TEA CO2 laser's 9RN16) branch line and its two sides branch line 9RGN 14) and the 9RN 18) branch line in NH3 gas are studied.The variation of energy conversion efficiency with pump energy is studied at a specific pressure. The energy conversion efficiency increases linearly with pump energy, and when the pump energy is 200 MJ, the energy conversion efficiency increases linearly with pump energy.The maximum energy conversion efficiency is 0.4.The variation of energy conversion efficiency with gas pressure is studied under the specific pump energy, and the pressure corresponding to the maximum energy conversion efficiency is about 550 Pa.This paper compares the theoretical and experimental studies on energy conversion efficiency, analyzes the causes of errors, and points out the advantages and disadvantages of the theoretical model and the direction of further research.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248.22

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