Fast Reconfigurable Phase Shifter Based on a Chiral Liquid Crystal Configuration

Abstract

Liquid crystals (LCs) offer a promising playground for developing reconfigurable radio frequency devices due to their unique dielectric properties, including large birefringence and tunability. Previous research on reconfigurable phase shifters has primarily focused on studying loss, response, and tunability. However, the influence of surface-enforced alignment on LC remains an area that requires further exploration. Here, we designed a phase shifter using twisted nematic aligned cells. To characterize the phaseshifting behavior of the nematic LC, we employed the transmission line method within the frequency range of 5 to 8 GHz and extracted the dynamic electrical parameters. Numerical simulations based on finite element methods were conducted to predict the alignment of LC molecules and the propagation of waves within the test cell. The phase shifter achieved a phase difference of ∼220 • by applying a bias voltage to the LC. In particular, we compare the dynamic response of the phase shifter and a twisted LC configuration having a chiral dopant that responds 10 times faster than the homogeneous mode.INDEX TERMS Liquid crystal, dielectric anisotropy, phase shifter, twisted nematic configuration, chiral dopant.DOWON KIM (Member, IEEE) received the M.S. and Ph.D. degrees in electrical engineering from

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“…Several advanced reconfigurable liquid crystal-based devices have been developed, including fast-reconfigurable phase shifters, devices for generating optical vortices, LC-based reconfigurable intelligent surfaces, and liquid crystal gratings. For example, Kim et al designed a fast-reconfigurable phase shifter utilizing liquid crystal, evaluating its performance for twisted nematic and antiparallel alignment liquid crystal cell configurations 4 . Albero et al developed two reconfigurable LC devices to generate optical vortices.…”