Effect of mode characteristics of hole-output-coupling THz gas laser
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摘要: 孔径光阑耦合技术是大功率光泵气体太赫兹激光器的一种常用谐振腔设计方法。在不考虑波导对腔内模式形成的影响下，采用传输矩阵的特征向量法，针对孔径光阑耦合太赫兹谐振腔的腔内本征模式以及输出光束特性进行了数值模拟，得到了该种谐振腔在不同g参数下损耗最低的几种本征模式及其相应的衍射损耗；采用衍射积分与矩阵光学结合的方法计算了孔径光阑输出太赫兹激光的光束特性，得到不同本征模式的远场衍射光斑及发散角。研究工作为孔径光阑耦合的气体太赫兹激光器设计提供了理论参考。Abstract: Hole-coupling technique is a most common design for high power optically-pumped terahertz gas lasers. In this paper, the intra-cavity modes and beam characteristics of the hole-coupling THz resonators have been numerically calculated with a co-called eigenvector method. Several lowest order modes and their diffraction losses of a series of hole-coupling THz resonators with different g parameters are given. The output beam characteristics from the small hole are studied with the diffraction integral associating with the matrix optical method. The far-field distributions and the divergence angles of each mode are computed.
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Key words:
- THz gas laser /
- hole-coupling /
- resonator modes /
- output beam characteristics
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图 1 孔径光阑耦合OPTL谐振腔结构示意图
Figure 1. Optical schema of OPTL with single hole-coupling technique
图 2 低阶模的单程衍射损耗随g参数从0至1变化的曲线
Figure 2. Curves of the one-way pass diffraction losses of the lowest order modes
图 3 孔径光阑耦合太赫兹谐振腔损耗最低的三种横模
Figure 3. Three lowest loss eigenmodes of hole-coupling OPTL
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