Observation of a different birefringence order at optical and THz frequencies in LBO crystal
Observation of a different birefringence order at optical and THz frequencies in LBO crystal
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DOI：
10.1016/j.optmat.2017.01.031
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发表时间：
2017-04-01
影响因子：
3.9
通讯作者：
Svetlichnyi, V. A.
中科院分区：
文献类型：
--
作者：
Andreev, Yu. M.;Kokh, A. E.;Svetlichnyi, V. A.
用时域谱(TDS)测量了硼酸锂(LBO)晶体的太赫兹光学性质。LBO晶体样品具有高光学质量，并沿<；100>；、<；010>；和<；001>；轴进行切割和抛光。为了确认结果的重复性和一致性，进行了两次独立的测量。澄清了以前发表的关于LBO的THz光学性质的数据中的矛盾。结果表明，在太赫兹频率下的双折射级数为n(Z)<；n(X)<；n(Y)，而在光学频率下的双折射级数为n(X)<；n(Y)<；nz。可见，NZ在可见光中的值最高，而在太赫兹处的值最低。这是用离子极化率来解释的，并与沿Z轴极化的波的太赫兹吸收系数比X轴和Y轴低一个数量级以上的事实一致。对于平行于Z轴的极化波，在0.5太赫兹频率下的吸收低至0.2 cm(-1)。设计了一组适用于整个透明度范围的新的色散方程。(C)2017爱思唯尔B.V.保留所有权利。
THz optical properties of lithium borate (LBO) crystals were measured using time-domain spectroscopy (TDS). The LBO crystal samples were of high optical quality and were cut and polished along the < 100 >, < 010 > and < 001 > axes. Two independent measurements were performed in order to confirm the reproducibility and consistency of results. The contradictions in the previously published data on the THz optical properties of LBO were clarified. It was shown that the birefringence order at THz frequencies is n(z) < n(x)< n(y), whereas at optical frequencies it is known to be n(x) < n(y) < nz. It was seen that nz, which has the highest value in the visible, has the lowest value at THz. This is explained in terms of ionic polarizability and is consistent with the fact that the THz absorption coefficient for a wave polarized along the Z-axis is more than an order of magnitude lower than for the X and Yaxes. Absorption as low as 0.2 cm(-1) was found at frequencies up to 0.5 THz for a wave polarized parallel to the Z-axis. A set of new dispersion equations was designed for the entire transparency range. (c) 2017 Elsevier B.V. All rights reserved.