서민아 교수

Unusual performances of metamaterials such as negative index of refraction, memory effect, and cloaking originate from the resonance features of the metallic composite atom(1-6). Indeed, control of metamaterial properties by changing dielectric environments of thin films below the metallic resonators has been demonstrated(7-11). However, the dynamic control ranges are still limited to less than a factor of 10,(7-11) with the applicable bandwidth defined by the sharp resonance features. Here, we

Abstract Terahertz (THz) shielding becomes increasingly important with the growing development of THz electronics and devices. Primarily materials based on carbon nanostructures or polymer–carbon nanocomposites have been explored for this application. Herein, significantly enhanced THz shielding efficiencies for 2D titanium carbide (Ti 3 C 2 MXene) thin films with nanoscale THz metamaterials are presented. Nanoscale slot antenna arrays with strong resonances at certain frequencies enhance THz el

Abstract The terahertz (THz) spectrum is the focus of basic research in solid‐state physics, chemistry, and materials science as well as applications in next‐generation communications, far‐infrared bolometer, bio/chemical‐sensing, and medical imaging. This wavelength range is at the intersection between photonics and electronics, presenting tremendous opportunities to boost fundamental light–matter interactions enabled by plasmonic nanostructures, metamaterials, and inherent molecular vibrationa

As a candidate for a rapid detection of biomaterials, terahertz (THz) spectroscopy system can be considered with some advantage in non-destructive, label-free, and non-contact manner. Because protein-ligand binding energy is in the THz range, especially, most important conformational information in molecular interactions can be captured by THz electromagnetic wave. Based on the THz time-domain spectroscopy system, THz nano-metamaterial sensing chips were prepared for great enhancing of detection

We present 2D measurements of the full THz electric field behind a sample consisting of multiple slits in a metal foil. Our measurements, which have a sub-wavelength spatial, and a sub-period temporal resolution, reveal electric field lines, electric field vortices and saddle points. From our measurements we are able to reconstruct the magnetic field and, finally, the position and time-dependent Poynting vector which shows the flow of energy behind the sample. Our results show that it is possibl

We report that single-stranded deoxyribonucleic acids (ssDNAs) at very low concentrations can be detected using graphene-combined nano-slot-based terahertz (THz) resonance. A combination of the resonant structure and tuned electro-optical properties of graphene can provide unprecedentedly sensitive biomolecule sensing even using very low energy THz photons, overcoming the huge scale difference of 10,000:1 between the wavelength and the size of the ssDNAs. Ultrahigh sensitivity is obtained by the

Discrimination and quantification of trace amounts of steroid hormones in biological specimens are needed to elucidate their changing expression because their biological functions are responsible for the development and prevention of endocrine disorders. Although mass-spectrometry-based assays are most commonly recommended, development of a new type of highly sensitive and selective detection methods in clinical practices is needed. Here, we introduce a label-free type of terahertz molecule sens

Abstract Understanding light interaction with metallic structures provides opportunities of manipulation of light, and is at the core of various research areas including terahertz (THz) optics from which diverse applications are now emerging. For instance, THz waves take full advantage of the interaction to have strong field enhancement that compensates their relatively low photon energy. As the THz field enhancement have boosted THz nonlinear studies and relevant applications, further understan

Terahertz (THz) technology has become more widespread due to its diverse range of potential applications, particularly when combined with various functional metamaterials using cutting-edge nanotechnology techniques. In this report, we introduce a highly improved THz imaging technology by comparing complementary metamaterials intuitively based on Babinet’s principle. The THz reflectance spectra for the complementary metamaterials exhibit a significant and distinct association with the polarizati

We performed time-domain terahertz spectroscopy on thin layers of single-walled carbon nanotubes (SWCNTs) coated on flexible films. The SWCNT layers demonstrate good shielding of electromagnetic waves in the terahertz range while maintaining good transparency for visible light. The shielding efficiency can be engineered through the thickness control and/or chemical treatment of SWCNT layers. The frequency-dependent dielectric constants of SWCNT layers are in good agreement with the Drude free-el

We performed terahertz near-field experiments on single rectangular holes with various lengths grown on an electro-optic crystal substrate with lambda/100 resolution. We find that the near-field amplitude becomes proportionally larger as the rectangle becomes narrower, strongly suggesting that a constant energy passes through even for a very narrow slit. The occurrence of a large field enhancement at the fundamental localized resonance is discussed confirming the funneling of energy at the near-

The development of effective assay techniques for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has recently received research attention due to its rapid worldwide spread and considerable risk to human health. The receptor-binding domain (RBD) of the spike (S) protein in SARS-CoV-2, a key component for viral entry that has a unique sequence compared to other structural proteins, has been considered an important diagnostic target. In this respect, low-frequency vibrational modes ha

A method for manufacturing terahertz absorber is presented. Varying fractions of graphite powder are mixed with the host poly methylmethacrylate powder and compress molded. The shielding efficiency, together with real and imaginary parts of the dielectric constant, is unambiguously determined by terahertz time domain spectroscopy in the continuous frequency range of 0.1–1.6THz. While the composites are absorptive in most of the frequency range with relatively small reflection, it turns metallic