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Tunable terahertz fishnet metamaterials based on thin nematic liquid crystal layers for fast switching.

Zografopoulos DC, Beccherelli R - Sci Rep (2015)

Bottom Line: A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values.Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components.Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

View Article: PubMed Central - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi (CNR-IMM), Roma 00133, Italy.

ABSTRACT
The electrically tunable properties of liquid-crystal fishnet metamaterials are theoretically investigated in the terahertz spectrum. A nematic liquid crystal layer is introduced between two fishnet metallic structures, forming a voltage-controlled metamaterial cavity. Tuning of the nematic molecular orientation is shown to shift the magnetic resonance frequency of the metamaterial and its overall electromagnetic response. A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values. Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components. Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

No MeSH data available.


Schematic layout and geometrical parameter definition of the proposed LC-tunable fishnet terahertz metamaterial.The fishnet metallic network is patterned on a low-loss THz dielectric substrate and a liquid-crystal cavity is formed between two opposing fishnet slabs.
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f1: Schematic layout and geometrical parameter definition of the proposed LC-tunable fishnet terahertz metamaterial.The fishnet metallic network is patterned on a low-loss THz dielectric substrate and a liquid-crystal cavity is formed between two opposing fishnet slabs.

Mentions: The layout of the proposed LC-THz-MM is shown in Fig. 1. The fishnet periodic structure is made of gold and is characterized by the lattice constant Lx = Ly = 150 μm, the square patch dimension W, the stripe width w, and it is patterned on an infinite substrate of a low-loss THz polymer, e.g. Zeonor with a refractive index np = 1.51842. The metal thickness layer is Lm = 300 nm and that of the LC-dielectric layer Ls = 10 μm. The thickness Ls is controlled by placing dielectric spacers in the edges of the device, away from its active central region, so that they do not influence its EM properties. The permittivity of gold is described by the Drude model


Tunable terahertz fishnet metamaterials based on thin nematic liquid crystal layers for fast switching.

Zografopoulos DC, Beccherelli R - Sci Rep (2015)

Schematic layout and geometrical parameter definition of the proposed LC-tunable fishnet terahertz metamaterial.The fishnet metallic network is patterned on a low-loss THz dielectric substrate and a liquid-crystal cavity is formed between two opposing fishnet slabs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4536660&req=5

f1: Schematic layout and geometrical parameter definition of the proposed LC-tunable fishnet terahertz metamaterial.The fishnet metallic network is patterned on a low-loss THz dielectric substrate and a liquid-crystal cavity is formed between two opposing fishnet slabs.
Mentions: The layout of the proposed LC-THz-MM is shown in Fig. 1. The fishnet periodic structure is made of gold and is characterized by the lattice constant Lx = Ly = 150 μm, the square patch dimension W, the stripe width w, and it is patterned on an infinite substrate of a low-loss THz polymer, e.g. Zeonor with a refractive index np = 1.51842. The metal thickness layer is Lm = 300 nm and that of the LC-dielectric layer Ls = 10 μm. The thickness Ls is controlled by placing dielectric spacers in the edges of the device, away from its active central region, so that they do not influence its EM properties. The permittivity of gold is described by the Drude model

Bottom Line: A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values.Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components.Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

View Article: PubMed Central - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi (CNR-IMM), Roma 00133, Italy.

ABSTRACT
The electrically tunable properties of liquid-crystal fishnet metamaterials are theoretically investigated in the terahertz spectrum. A nematic liquid crystal layer is introduced between two fishnet metallic structures, forming a voltage-controlled metamaterial cavity. Tuning of the nematic molecular orientation is shown to shift the magnetic resonance frequency of the metamaterial and its overall electromagnetic response. A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values. Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components. Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

No MeSH data available.