Tunable terahertz band-pass filter based on MEMS reconfigurable metamaterials

Abstract

We present a tunable terahertz (THz) band-pass filter based on electrostatically actuated microelectromechanical systems reconfigurable metamaterials. The unit cell of the filter consists of a U-shaped structure and a fat-T shaped structure. The fat-T shaped structure connects with a movable frame which is actuated by two columns of electrostatic comb actuators. Initially, the filter has two passbands whose central resonance frequencies locate at 0.66 THz and 1.31 THz, respectively. When the actuators are biased with direct currents (DC) voltages, the fat-T shaped structures will move to the U-shaped structures. Thus, the transmition of the peak at 0.66 THz will decrease, and the modulation depth can reach 84.4%. Meanwhile, the resonance frequency of the high-frequency passband shows distinct blueshift, and the largest frequency shift arrives to 0.195 THz. The simulation results obtained from the finite-intergration-technology show that these two resonance peaks are produced by two LC resonators on the two arms and one resonator on the bottom of the U-shaped structure. A flinite element analysis method is introduced to study the electromechanical performance of the actuator, and a displacement of 4 µm is achieved at DC 120 V. The tunable THz band-pass filter can be applied in THz communication, THz frequency selection and THz sensing.

Design and simulation of a new narrow terahertz bandpass filter

“…The ratio of the original frequency to the unwanted frequencies in the output spectral range of the filter is the main advantage of the structure of this filter [31][32][33].…”

Metasurface-Based Optical Liquid Crystal Cell as an Ultrathin Spatial Phase Modulator for THz Applications

“…Metamaterials have revolutionized the way electromagnetic waves can be manipulated and controlled, 18 and enabled a substantial improvement in the performance of terahertz devices. [19][20][21][22][23] In particular, efficient modulation of THz radiation was achieved by hybridizing metamaterials with chalcogenides, 24,25 phase change metal oxides, 26,27 semiconductors, 28,29 micro electro-mechanical systems 30,31 and graphene. 32,33 LC hybridized metamaterials have contributed significantly to the development of effective modulators, 34,35 tunable filters, 36,37 switchers, 38,39 and SLMs 40,41 for a wide spectral range from visible to THz frequencies.…”

“…We argue that the operational principle of LC-based SLMs can be readily extended on the spatial modulation of terahertz wavefronts with the use of metamaterial technology. Metamaterials have revolutionized the way electromagnetic waves can be manipulated and controlled and enabled a substantial improvement in the performance of terahertz devices. − In particular, efficient modulation of THz radiation was achieved by hybridizing metamaterials with chalcogenides, , phase change metal oxides, , semiconductors, , micro electro-mechanical systems, , and graphene. , LC-hybridized metamaterials have contributed significantly to the development of effective modulators, , tunable filters, , switchers, , and SLMs , for a wide spectral range from visible to THz frequencies. A particularly efficient electrically driven mechanism of amplitude and phase modulation of THz radiation has been demonstrated in transmission with a thin low-voltage LC cell combined with a resonant 2D metamaterial and, later, 3D metamaterial .…”

Thickness Effect on (La 0.26 Bi 0.74 ) 2 Ti 4 O 11 Thin-Film Composition and Electrical Properties

“…The advantage of PLD deposition is that it can faithfully transfer the right chemical composition to the films, and the La modification can improve the film crystallization in lowering of film leakage currents. [6,9] For electric characterization, a metallic LaNiO 3 (LNO) bottom layer with the thickness of 100 nm was previously deposited on STO under the identical condition. Here the lattice parameters of the LaNiO 3 buffer layer closely match with those of the STO substrate.…”

“…The morphologic phase transformation is similar to the high-temperature sintering of (La,Bi) 4 Ti 3 O 12 and (La,Bi) 2 Ti 4 O 11 ceramics. [6,9] The (La,Bi) 4 Ti 3 O 12 component is ferroelectric, as implicated from twolayer modeling of current transients with time. Comprehensive longtime charge injection into two component interfaces occurs above a coercive voltage along with ferroelectric domain switching.…”