Friday, June 17, 2016

Abstract-Polarization-independent 2 pi phase modulation for Terahertz using chiral nematic liquid crystals

Chun-Ta Wang, Chung-Lun Wu, Han-Wei Zhang, Tsung-Hsien Lin, and Chao-Kuei Lee

The manipulation of terahertz (THz) signals, such as in phase control with modulation depths of 2π, is an important subject in THz photonics. In this work, an electrically controllable chiral liquid crystal (Ch-LC) cell with low chirality is used to develop a THz phase modulator with 2π tunability. The proposed Ch-LC device is insensitive to the polarization of electromagnetic waves in THz frequency range. The diluted chiral dopant enables the critical voltage of the Ch-LC cell to be effectively reduced to 0.24 V/μm from 3.65 for a typical Ch-LC cell with high chirality. The dependence of phase retardation on driving field and the polarization is examined. This THz 2π phase modulator has great potential for practical use.
© 2016 Optical Society of America
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