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A broadband terahertz absorber based on plasmonic cross structure resonators is proposed and investigated. This plasmonic absorber yields above 90% absorbance from 0.67 THz to 1.78 THz in the simulation, compared with 0.74 THz to 1.62 THz in the experiment. The remarkable absorption bandwidth of about 90% in theory can be associated with two plasmonic resonances supported by the cavities bounded by...
Terahertz ellipsometric and polarimetric measurement systems have been commissioned with the Novosibirsk free electron laser (FEL) being a source of monochromatic radiation. Calibration experiments with semiconductors and metamaterials showed correct operation of these systems. Blood films, monosaccharide, amino acids, and culture medium were studied.
We designed, fabricated and characterized a tunable metamaterial in the terahertz frequency range based on a hybrid topology composed of metallic cut-wires separated by vanadium dioxide (VO2) patterns. The response of the hybrid metamaterial is significantly changing as the VO2 material is performing a reversible thermally or electrically-driven metal-insulator transition which drastically modifies...
Metamaterial-based waveguides offer unusual phenomena compared to conventional metallic and dielectric waveguides. We present a novel waveguide based on metamaterials, an air-core waveguide with a magnetic metamaterial cladding assembled from split ring resonator fibers. The transmission properties of the waveguide in the terahertz region are characterized both experimentally and numerically. Such...
Using flexible multi-layer metamaterial (MM), we make a wideband passband filter at THz. The center frequency is about 0.89 THz with a 3dB bandwidth of 0.69 THz for normal incidence. The sharp band-edge transitions are 53 dB/THz and 70 dB/THz to the rejection bands, respectively. The measured average insertion loss is 1.4 dB with a ripple of 0.8 dB. We also use a multi-band EIT-like MM to detect the...
When THz filters are designed, several geometric/material parameters (variables) can affect its properties. In this context, one often meets the task of having to reconstruct a multivariable response-surface in order to determine how the different parameters affect the filter response, which often requires substantial computation time. In this work, we develop a modified bisection method to choose...
We demonstrate a design of terahertz metamaterial bandstop filter, which is based on arrays of split-ring resonators (SRRs) and pair rods of vanadium dioxide (VO2). Each unit cell comprises a pair of SRRs with their splits in opposite directions and a pair of VO2 rods crossing the SRR perpendicular to the split directions. Two stopband electromagnetic resonances can be switched by optical-pumping...
A combination of continuous wave optical illumination and electrical gating leads to a giant active modulation (∼61%) of terahertz waves in a graphene-silicon hybrid metamaterial at extremely low gate bias voltages (1 V). The highly tunable characteristics of the graphene metamaterial device under electrical bias and optical illumination open up new avenues for graphene-based high performance integrated...
After passing quarter of a century from its discovery, terahertz time-domain spectroscopy (THz-TDS) has made great progress and is expected to be applied to various fields from basic science to security and industry. I will review our contribution to the development and applications of THz-TDS including recent results.
Fabry-Perot resonances in planar terahertz metamaterial structures have been investigated both theoretically and experimentally. It has been demonstrated that performance of frequency-agile metamaterial modulator can be optimized by adjustment of dielectric substrate thickness in accordance with operating frequency of metamaterial.
The polarization response of THz wavelength metamaterials modulators have been researched, and a special modulator structure has been proposed, simulated and fabricated. Compared with the traditional split ring resonator modulators which are all polarization sensitive, the new structure has properties of polarization insensitive. The structure is a completely symmetrical metal structure and has the...
Spatially different arrangements of identical metaatoms in a unit cell bring about distinct properties in stereometamaterials. Integrating the stereometamaterial into a perfect metamaterial absorber, we designed, fabricated, and characterized a device with single or double band absorption responses and an absorption/reflection switching characteristic dependent upon the polarization of the incident...
The effects of bending a 2-dimensional planar array of rectangular split-ring resonators (SRRs) is observed by mounting the array to varying diameter HDPE cylinders. By studying the transmission of pulsed THz light through the SRR-cylinder system, it shown that the resonant frequency and response of the arrays are tunable as a function of the radius of curvature.
A broadband terahertz reflective linear polarization convertor is proposed. The structure is composed of a metallic disk and split-ring resonators in proximity to a ground plane. It is found that the structure exhibits three neighboring resonances, from which the linear polarization of incident light can be rotated to its orthogonal counterpart after reflection. Both simulated and experimental results...
We present a numerical simulation of frequency-agile terahertz metamaterials which incorporate semiconducting material as an integral part of the resonant elements to split ring resonator (SSR). The resonance frequency of the metamaterial can be dynamical tune through photoexcitation. The modification of capacitance at the split gap by photoexcitation results in red-shifting of metamaterial resonance...
A terahertz detector composed of a metamaterial absorber and micro-bolometer sensor integrated in a standard CMOS process is presented. The prototype demonstrates an innovative, uncooled, low cost, compact terahertz detector that is readily scaleable to high resolution focal plane array formats. The detector imaging capability is demonstrated in a transmission mode experiment.
We use subwavelength metal rigs to control THz transmission through a planar dielectric waveguide. In this case magnetic field has maximal projection on the current loops. Transmission enhancement is observed in a narrow frequency band for a particular orientation of rings gaps and field polarization.
In this study, we demonstrate novel asymmetric metamolecule arrays with multiple sharp resonances. They reveal a new Fano-like mode due to the collective excitation of the metamolecules. Q-factors as high as 38 have been achieved. In the future, such resonances could be used in sensor and filter applications.
Classic analog of the electromagnetically induced transparency (EIT) in metamaterials has been demonstrated extensively by its attractive potential applications in light storage, slow light and sensing. However, the counterpart of EIT, electromagnetically induced absorption (EIA) has been studied rarely in coupled metamaterial systems. Here, we present the observation of the EIA effect in a vertically...
We present a new fabrication technique for silicon-based optically tunable metamaterial membranes. The realized bandpass filter is only 25 μm thick, enabling quasi etalon-free performance. The maximal amplitude transmission of the filter was 80 %, and an amplitude modulation depth of 94 % was achieved at 0.65THz using a 500mW strong modulation laser.
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