文档介绍：华中科技大学
硕士学位论文
基于非线性光学频率变换产生太赫兹辐射源的研究
姓名:李三星
申请学位级别:硕士
专业:光学工程
指导教师:姚建铨
2010-12-28
华中科技大学硕士学位论文
摘要
太赫兹波由于在电磁谱中的特殊位置,可广泛地应用于生物医学,安全检查,环境
监测等众多领域,性能优良的太赫兹辐射源是实现这些应用的基础。产生太赫兹辐射
源的众多方法中,非线性光学频率变换具有光路结构简单,调谐方便,输出功率较高
等诸多优点。本论文介绍了差频和太赫兹参量振荡两种非线性光学频率变换方法。
本文分析了差频中非共线,双折射共线,剩余色散带共线三种相位匹配方式,通
过数值模拟得到了它们各自的角度调谐曲线。差频泵浦源选择二氧化碳激光器时,进
行了相应的光路设计。由于陶瓷光纤激光器可通过同一谐振腔产生频率接近的两束光,
分析表明利用陶瓷光纤激光器作差频泵浦源有望得到高功率,体积小的太赫兹辐射源。
从晶格振动理论出发,本文得到了太赫兹参量振荡过程中参量增益的表达式和格
波色散关系。根据格波色散关系和相位匹配通过数值计算得到了 LiNbO3 晶体的角度调
谐曲线。根据晶体晶格振动模的分布,理论上计算了参量增益随太赫兹频率和泵浦光
能量的变化。实验上测量了 LiNbO3 和 MgO:LiNbO3 两种晶体的角度调谐曲线,两者频
率调谐范围分别为:- 和 -。测量了太赫兹输出能量随太赫兹波
频率及泵浦光能量的变化。当输入泵浦光能量为 ,在处得到
MgO:LiNbO3 晶体最高输出能量对应电压值为。通过线性拟合的方法测量得到
-1
了 LiNbO3 晶体在处吸收系数为 ,MgO:LiNbO3 晶体在处吸
收系数为 -1。

关键词: 差频相位匹配角度调谐太赫兹参量振荡 LiNbO3 MgO:LiNbO3
参量增益

I
华中科技大学硕士学位论文
ABSTRACT
Terahertz wave can be extensively used for biomedicine, safety inspection,
environmental monitoring and so on. All the applications can be realized based on the
terahertz radiation source with superior performance. There are many methods for genera-
ting terahertz wave among which there are lots of advantages for the method of nonlinear
optical frequency conversion, for example simple optical structure, easy tuning, high output
power and so on. Two methods were intruduced in the Master’s thesis, which are Difference
Frequency Generation (DFG) and Terahertz Parametric Oscillator(TPO).
Three Phase-matching methods were intruduced, which are Phase-matching of
nonlinear, birefringence collinear and reststrahlen band collinear. The angle tuning curves
were obtained by numerical simulations. When the pump source of DFG is CO2 Laser, the
corresponding optical design was obtained. Because two laser beams can be generated in the
same cavity for the Ceramic Fiber Laser(CFL), Compact terahertz radiation source with high
output power can be realized with