Arrayed silicon prism coupler for a terahertz-wave parametric oscillator.
Arrayed silicon prism coupler for a terahertz-wave parametric oscillator.
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DOI：
10.1364/ao.40.001423
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发表时间：
2001-03
期刊：
影响因子：
1.9
通讯作者：
K. Kawase;J. Shikata;H. Minamide;K. Imai;Hiromasa Ito
中科院分区：
文献类型：
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作者：
K. Kawase;J. Shikata;H. Minamide;K. Imai;Hiromasa Ito
利用调Q Nd：YAG激光器泵浦LiNbO 3晶体的室温参量振荡，以简单的结构实现了1 ~ 3 THz宽调谐相干太赫兹（THz）光源。由于太赫兹波在晶体边缘受到全内反射的影响，我们使用硅棱镜耦合器来耦合出太赫兹波。介绍了一种提高效率、减小衍射角的阵列硅棱镜耦合器。与使用单棱镜耦合器相比，使用阵列棱镜耦合器，耦合效率提高了6倍，远场光束直径减小了40%。讨论了散射泵浦光激发的硅棱镜表面自由载流子的负效应，以及谐振腔旋转对硅棱镜THz波单向辐射的正效应。
Using room-temperature parametric oscillation of a LiNbO3 crystal pumped by a Q-switched Nd:YAG laser with a simple configuration, we have realized a widely tunable coherent terahertz- (THz-) wave source in the range between 1 and 3 THz. Inasmuch as the THz wave is affected by total internal reflection at the crystal edge, we used a Si prism coupler to couple out the THz wave. We introduce an arrayed Si-prism coupler that increases the efficiency and decreases the diffraction angle. By use of the arrayed-prism coupler, there is a sixfold increase in coupling efficiency and a 40% decrease in the far-field beam diameter, compared with the use of a single-prism coupler. We discuss the negative effect of the free carriers at the Si-prism surface that is excited by the scattered pump beam, and the positive effect of cavity rotation on the unidirectional radiation of the THz wave from a Si prism.