A Study of the Optical Properties and Applications of Liquid Crystals in THz Range

• Main Authors: Chen, Chao-Yuan, 陳昭遠
• Other Authors: Ci-Ling Pan
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/62211325039840623871

博士 === 國立交通大學 === 光電工程系所 === 94 === The complex refractive indices of some typical nematic liquid crystal (LCs), 5CB and E7, in the THz frequency range have been determined by using the terahertz (THz) time-domain spectroscopy. For 5CB, no~1.58 and ne~1.78, and the birefringence is as high as 0.20 throughout this frequency range. Using magnetically controlled birefringence in 5CB and E7, the room temperature liquid crystal THz phase shifters/retarders have been demonstrated successfully. A phase shift over 2�� at 1 THz is achieved by employing a sandwiched cell structure. Using the tunable phase retarder, we also demonstrated the first THz tunable Lyot filter to our knowledge. The central passband frequency of the filter can be continuously tuned from 0.388 THz to 0.564 THz (a fractional tuning range of 40%).