Browsing by Author "Shih, Fang-Cih"

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Liquid-crystal-based magnetically tunable terahertz achromatic quarter-wave plate
(2019-04-01)
Hsieh, Cho-Fan
;
Yang, Chan-Shan
;
Shih, Fang-Cih
;
Pan, Ru-Pin
;
Pan, Ci-Ling
Development of the wideband and tunable quasi-optic terahertz (THz) components is in high demand. In this work, we demonstrate a tunable achromatic quarter-wave plate (AQWP) for the THz frequency range. The phase retardation of this device can be set at 90 degrees +/- 9 degrees from 0.20 to 0.50 THz. The operation range from 0.20 to 0.50 THz can be tuned to from 0.30 to 0.70 THz by introducing three nematic liquid crystals phase retarders, of which the birefringence can be magnetically tuned. The frequency-dependent phase retardation is in good agreement with theoretical predictions. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Liquid-crystal-enabled Electrically Tunable Terahertz Achromatic-wave Plate
(2016)
Yang, Chan-Shan
;
Shih, Fang-Cih
;
Pan, Ru-Pin
;
Yu, Peichen
;
Pan, Ci-Ling
A THz achromatic quarter-wave plate (AQWP) based on liquid-crystal (LC) phase shifters which have different thickness and orientations, respectively, has been designed and demonstrated. Electrical properties for LC cells is taken into account as well to be used to compensate the thickness of the cell and to accomplish the aim of achromatic tunability. Indium-tinoxide nanowhiskers which show outstanding THz transmittance are employed as the transparent electrodes in AQWP. The performance of the AQWP analyzed by Stokes parameters have shown the achromatic ability in the frequency range of 0.2 similar to 0.8 THz, and can be electrically tuned to 0.3 similar to 0.9 THz.