標題: | Recent progress in liquid crystal THz optics - art. no. 61350D |
作者: | Pan, Ci-Ling Pan, Ru-Pin 光電工程學系 Department of Photonics |
關鍵字: | THz;liquid-crystal devices;far Infrared;phase shifters;wave plate;Lyot filter |
公開日期: | 2006 |
摘要: | Recently, there have been increasing interests in the study of liquid-crystal-based devices for application in the submillimeter wave or THz frequency range. In this paper, we present recent progress in liquid crystal THz optics from our group. Using time-domain THz spectroscopy, we have determined the complex indices of refraction of nematic liquid crystals, 5CB, PCH5 and E7 from 0.2 to beyond 1 THz. Significantly, the birefrincrence of 5CB and E7 are found to be as large as 0.2 at THz frequencies, while the absorption is negligible. Electrical-field and magnetic-field-controlled birefringence in LC were also investigated. A tunable room-temperature THz phase shifter using magnetic-field-controlled birefringence in nematic 5CB gives a phase shift as large as 108 degrees at 1.0 THz. Phase shift exceeding 360 degrees at 1 THz, an important milestone, was realized by using a sandwiched LC (E7, Merck) cell as thick as 3 nun. The magnetically tuned LC phase shifter served as key components in a two-element tunable LC Lyot filter. The tuning range of the filter is from 0.388 to 0.564 THz or a fractional tuning range of similar to 40%. Our work clearly demonstrates the potential of liquid crystal devices for THz applications. Finally, we will present initial works on control of enhanced THz transmission through a metallic hole array with nematic liquid crystals. Our work clearly demonstrates the potential of liquid crystal devices for THz applications. |
URI: | http://hdl.handle.net/11536/17130 http://dx.doi.org/10.1117/12.644527 |
ISBN: | 0-8194-6177-6 |
ISSN: | 0277-786X |
DOI: | 10.1117/12.644527 |
期刊: | Liquid Crystal Materials, Devices, and Applications XI |
Volume: | 6135 |
起始頁: | D1350 |
結束頁: | D1350 |
顯示於類別: | 會議論文 |