Electrically controllable fishnet metamaterial based on nematic liquid crystal

Abstract

A variable index metamaterial is demonstrated by embedding nematic liquid crystal inside fishnet layers' void at microwave frequencies. With an external electric field, the left handed passband can be reversibly shifted from 9.14 to 8.80 GHz, whereas the upper right handed passband is nearly unchanged. It is shown that during LC molecular reorientation, magnetic resonance is shifted to a lower frequency because of the permittivity increase between fishnet layers, leading to an effective index change of 1.1 within negative index regime.

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

“…The fluid nature of NLC's and their compatibility with other widely used materials ranging from semiconductors to polymers and plasmonics (metals) enable easy integration of such 'crystal' into a large assortment of non-planar structures ranging from nm-sized photonics elements [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] such as inverse opal photonic crystals and plasmonic/metamaterial structures, c.f. Figures 2(c)-(d), to millimeter-or bulkier microwave devices for tunable -delay line, -phase shifter, -wavelength selector and beam steering devices [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], to name a few.…”

“…Figure 13(a) that tends to diminish the overall response of the NLC-infiltrated structures such as inverse opal photonic crystal or micro-ring resonator [7,11]. In complex non-planar structures with numerous tight corners and crevices such as fishnet or splitring metamaterials other sub-wavelength structures and resonators [12][13][14][15][16][17][18][19][20][21][22][23][24][25] non-uniform director axis alignment, c.f. Figure 13(b) in addition to the immobile layer significantly diminish the effective tunable birefringence of the NLC and device performance.…”

Transient responses of liquid crystals for optical switching with microseconds: nanoseconds response speed

“…Due to their fluidity and large birefringence that extends from optical to very long wavelength regime, nematic liquid crystals (NLC) have become a favorite material for incorporation into various photonic structures including photonic crystal inverse opals 24 , frequency selective surfaces 25 , channel waveguide and micro-ring resonator 26,27 , nanostructured plasmonic and metamaterials [28][29][30][31][32][33][34][35] . By inclusion of dye or azo-molecular dopants, and a variety of plasmonic nmparticulates, enhanced nonlinear or electro-optics response as well as metamaterials with emergent properties have been obtained 6,32 .…”

The interaction of electromagnetic waves with VO2 nanosized spheres and films in optical and extremely high frequency range.

“…So it should be noted the configurable antennas and metasurfaces [1], based on a change in carrier substrate density [2][3][4][5], active devices based on liquid crystals, functioning by changing the effective index of a liquid crystal by an electric and magnetic field [6,7] and electrically controlled active devices [8][9][10]. According to many reports, materials with phase transitions (PT), for example, metal-insulator transition (MIT), are the most promising materials for creating the devices described above with control properties.…”