ㄧ系列液態晶體在兆赫波段下的光學常數

Abstract

我們利用兆赫波時域頻譜儀 (THz-TDS)量測nCB（n=6-12）系列液晶在兆赫波段下的光學性質。實驗結果顯示6CB、7CB和8CB在兆赫波段下的雙折射率範圍分別為0.106-0.130、0.059-0.115和0.077-0.124。根據文獻[12]，6CB、7CB和8CB在可見光下的雙折射率範圍分別為0.109-0.143、0.123-0.171和0.093-0.153。9CB、10CB、11CB和12CB在液態時的折射率分別為1.56、1.60、1.55和1.56，其吸收係數均小於0.05。液晶nCB（n=6 to 12）在0.2-1.6THz都沒有明顯的吸收頻譜。

The complex refractive indices of the homologous series of alkyl cyanobiphenyl liquid crystals（nCB，n=6 to 12）have been determined by using the terahertz time-domain spectroscopy. We have shown that the terahertz（0.2-1.6THz）birefringence of 6CB, 7CB, and 8CB are 0.106-0.130, 0.059-0.115, and 0.077-0.124, respectively. Based on the bibliography, the visible birefringence of 6CB, 7CB, and 8CB are 0.109-0.143, 0.123-0.171, and 0.093-0.153, respectively. The real indices of 9CB, 10CB, 11CB and 12CB in isotropic phase are around 1.56, 1.60, 1.55 and 1.56, respectively. Their extinction coefficients are all less than 0.05. There is no sharp absorption features of nCB（n=6 to 12）in the range of 0.2-1.6THz.