Abstract-Tunable reflective liquid crystal terahertz waveplates

Lei Wang, Shijun Ge, Wei Hu, Makoto Nakajima, and Yanqing Lu

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-7-6-2023&origin=search

Tunable liquid crystal devices that can change terahertz wave polarization continuously have many potential applications in terahertz optical systems. We present a reflective liquid crystal terahertz waveplate with sub-wavelength metal grating and metal ground plane electrodes. The thickness of the liquid crystal layer can be reduced to ~10% of that needed for the same phase shift at a given frequency in a transmissive waveplate. We experimentally demonstrate the same tunability as in the transmissive type just using half the thickness. We discuss the dependence on the angle of incidence for phase shift tunability, which can achieve beam steering and polarization conversion simultaneously. The proposed design can be applied in terahertz imaging, sensing, and communications.

© 2017 Optical Society of America

Abstract-Voltage-controlled liquid-crystal terahertz phase shifter with indium–tin–oxide nanowhiskers as transparent electrodes

Chan-Shan Yang, Tsung-Ta Tang, Po-Han Chen, Ru-Pin Pan, Peichen Yu, and Ci-Ling Pan  »View Author Affiliations

Optics Letters, Vol. 39, Issue 8, pp. 2511-2513 (2014)
http://dx.doi.org/10.1364/OL.39.002511

http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-39-8-2511

Indium–tin–oxide nanowhiskers were employed as transparent electrodes in a liquid-crystal terahertz phase shifter. Transmittance of the device was as high as ∼75%. Phase shift exceeding π/2 at 1.0 THz is achieved in a ∼500  μm-thick cell. The driving voltage required for the device operating as a quarter-wave plate was as low as 17.68 V (rms), an improvement of nearly an order of magnitude over previous work.

© 2014 Optical Society of America