Broadband multi-layer terahertz metamaterials fabrication and characterization on flexible substrates

Abstract

Microscopic split-ring-resonator (SRR) arrays are fabricated on 100 μm thick polyethylene naphthalate (PEN) films by femtosecond laser micro-lens array (MLA) lithography. The transmission properties of these metamaterials are characterized by THz Time Domain Spectroscopy (THz-TDS). Tunable resonance responses can be achieved by changing SRR structural design parameters. By stacking 2D PEN metamaterial films with different frequency responses together, a broadband THz filter with full width at half maximum (FWHM) of 0.38 THz is constructed. The bandwidth of the resonance response increases up to 4.2 times as compared to the bandwidths of single layer metamaterials. Numerical simulation reveals that SRR layers inside the multi-layer metamaterials are selectively excited towards specific frequencies within the broadband response. Meanwhile, more than one SRR layers respond to the chosen frequencies, resulting in the enhancement of the resonance properties. The multi-layer metamaterials provide a promising way to extend SRR based metamaterial operating region from narrowband to broadband with a tunable feature.

Mechanically tunable terahertz metamaterials

“…With the advancement of polymer technology and lithographic techniques, it is possible to fabricate metamaterials on thin flexible substrates, including Kapton polyimide, 13,14 polyethylene naphthalate (PEN), 15,16 and polydimethylsiloxane (PDMS). 17 Conformal deformation of flexible terahertz metamaterials has been demonstrated with some reports showing that wrapping these materials onto cylinders with different radii can adjust their resonance frequencies, 18,19 while another reports shows that wrinkling a rigid metamaterial on a soft backing layer surface can influence the response.…”

Realization of Variable Three‐Dimensional Terahertz Metamaterial Tubes for Passive Resonance Tunability

“…[ 16 ] In recent research, fl exible PEN fi lms were used as substrates to construct metamaterials for resonance enhancement and broadband resonance. [17][18][19] This kind of thin fl exible metamaterial can make metamaterials into non-planar form, allowing more potential designs and applications than the metamaterials made on rigid substrates.…”

Triple Band Circular Ring-Shaped Metamaterial Absorber for X-Band Applications

“…The structures are typically developed by periodic arrangement of metallic unit cell on dielectric layer. Some metamaterials are designed in aperiodic form [2], and some are designed by having multiple layers with same materials [3] or different materials [4]. An example of metamaterial is left-handed metamaterial which was designed using the principle of double negative permeability, µ, and permittivity, ε, [5][6][7].…”