Sub-Second Switching Speed Polarization-Independent 2 pi Terahertz Phase Shifter

This study develops a 2 pi terahertz (THz) phase shifter that stacks three layers of cholesteric liquid crystal (CLC) cells. Each CLC cell in the focal conic state with randomly helical structures exhibits isotropic properties for a THz wave and enables polarization independence. An external vertical electric field is applied to modulate the refractive index of the CLC cells by switching the liquid crystals between focal conic and homeotropic states. The driving voltage and response time were significantly improved by the multi-stacking technique relative to that of a 5-mm-thick CLC-based 2 pi THz phase shifter, whose critical voltage is as high as 1200 V and response time is tens of seconds. The proposed multilayer device has a relatively small critical voltage of 400 V and a short response time of less than 1 s.

[1]  N. Vieweg,et al.  Liquid crystal based electrically switchable Bragg structure for THz waves. , 2009, Optics express.

[2]  N. Vieweg,et al.  Electrically Tunable Terahertz Notch Filters , 2012 .

[3]  R. Dabrowski,et al.  Fast Switching Liquid Crystals for Color-Sequential LCDs , 2007, Journal of Display Technology.

[4]  Willie J Padilla,et al.  Active terahertz metamaterial devices , 2006, Nature.

[5]  F. Castles,et al.  Flexoelectro-optic properties of chiral nematic liquid crystals in the uniform standing helix configuration. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[6]  Yan Zhang,et al.  Spatial Terahertz Modulator , 2013, Scientific Reports.

[7]  Mitsunori Saito,et al.  Polarization-independent refractive-index change of a cholesteric liquid crystal , 2015 .

[8]  Ci-Ling Pan,et al.  Electrically tunable room-temperature 2/spl pi/ liquid crystal terahertz phase shifter , 2006 .

[9]  Tsung-Hsien Lin,et al.  Polarization-independent 2 pi phase modulation for Terahertz using chiral nematic liquid crystals , 2016 .

[10]  N. I. Zheludev,et al.  Controlling intensity and phase of terahertz radiation with an optically thin liquid crystal-loaded metamaterial , 2013, 1307.6317.

[11]  D. Mittleman.  Sensing with terahertz radiation , 2003 .

[12]  Hyunsoo Yang,et al.  Graphene/liquid crystal based terahertz phase shifters. , 2013, Optics express.

[13]  Voltage-controlled 2π liquid-crystal terahertz phase shifter with indium-tin-oxide (ITO) nanowhiskers as transparent electrodes , 2014 .

[14]  Zhang Xi,et al.  Materials for terahertz science and technology , 2003 .

[15]  Paul L. McEuen,et al.  Terahertz imaging and spectroscopy of large-area single-layer graphene , 2011, CLEO 2011.

[16]  Roman Dabrowski,et al.  Polymer stabilized liquid crystal phase shifter for terahertz waves. , 2013, Optics express.

[17]  Seung Hwan Ko,et al.  Fast Plasmonic Laser Nanowelding for a Cu‐Nanowire Percolation Network for Flexible Transparent Conductors and Stretchable Electronics , 2014, Advanced materials.

[18]  Makoto Nakajima,et al.  Tunable reflective liquid crystal terahertz waveplates , 2017, JSAP-OSA Joint Symposia 2017 Abstracts.

[19]  Emma Pickwell-MacPherson,et al.  The growth of biomedical terahertz research , 2014 .

[20]  Shin-Tson Wu,et al.  Infrared Properties Of Nematic Liquid Crystals: An Overview , 1987 .

[21]  Ru-Wen Peng,et al.  Freely Tunable Broadband Polarization Rotator for Terahertz Waves , 2015, Advanced materials.

[22]  Willie J Padilla,et al.  Liquid Crystal Metamaterial Absorber Spatial Light Modulator for THz Applications , 2014 .