THz Electromagnetic Waves Research Articles

Unified Theory of the Five Forces Adding the Fifth-Force by PicoHydrogen-Like Particles in the Water

We reported the hydrogen bond dissociating water, which we name MICA and SIGN water involving the presumed particle of infoton, <H+~ e- > formed by pressurization of tap water. We summarized the basic properties of both waters. The water obtains the smallness, reducibility, nuclear change in cesium and tritium, movement of particles, and emission of far IR through THz electromagnetic waves. These properties in the infoton unifies the five forces in every function. We tried the visualization of the water. We can explain every experience in daily life more than ten years corresponding to the basic infoton’s essence.

Terahertz waves regulate the mechanical unfolding of tau pre-mRNA hairpins

Intermolecular interactions, including hydrogen bonds, dominate the pairing and unpairing of nucleic acid chains in the transfer process of genetic information. The energy of THz waves just matches with the weak interactions, so THz waves may interact with biomolecules. Here, the dynamic effects of THz electromagnetic (EM) waves on the mechanical unfolding process of RNA hairpins (WT-30nt and its mutants, rHP, SARS-CoV-2, and SRV-1 SF206) are investigated using steered molecular dynamics (SMD) simulations. The results show that THz waves can either promote the unfolding of the double helix of the RNA hairpin during the initial unfolding phase (4-21.8 THz) or significantly enhance (23.8 and 25.5 THz) or weaken (37.4 and 41.2 THz) its structural stability during unfolding. Our findings have important implications for applying THz waves to regulate dynamic deconvolution processes, such as gene replication, transcription, and translation.

Effects of Terahertz Radiation on the Aggregation of Alzheimer’s Aβ42 Peptide

The pathophysiology of Alzheimer's disease is thought to be directly linked to the abnormal aggregation of β-amyloid (Aβ) in the nervous system as a common neurodegenerative disease. Consequently, researchers in many areas are actively looking for factors that affect Aβ aggregation. Numerous investigations have demonstrated that, in addition to chemical induction of Aβ aggregation, electromagnetic radiation may also affect Aβ aggregation. Terahertz waves are an emerging form of non-ionizing radiation that has the potential to affect the secondary bonding networks of biological systems, which in turn could affect the course of biochemical reactions by altering the conformation of biological macromolecules. As the primary radiation target in this investigation, the in vitro modeled Aβ42 aggregation system was examined using fluorescence spectrophotometry, supplemented by cellular simulations and transmission electron microscopy, to see how it responded to 3.1 THz radiation in various aggregation phases. The results demonstrated that in the nucleation aggregation stage, 3.1 THz electromagnetic waves promote Aβ42 monomer aggregation and that this promoting effect gradually diminishes with the exacerbation of the degree of aggregation. However, by the stage of oligomer aggregation into the original fiber, 3.1 THz electromagnetic waves exhibited an inhibitory effect. This leads us to the conclusion that terahertz radiation has an impact on the stability of the Aβ42 secondary structure, which in turn affects how Aβ42 molecules are recognized during the aggregation process and causes a seemingly aberrant biochemical response. Molecular dynamics simulation was employed to support the theory based on the aforementioned experimental observations and inferences.

Open investigation on the interaction length between a terahertz wave and an embedded dielectric ZRIM structure, and also phase tuning.

In this paper, we have focused on the near field behaviour of 2D Photonic Crystal-based dielectric zero refractive index metamaterial lattices with cylindrical silicon rods embedded in THz waveguides having PMC sidewalls. An "interaction length" is expected in both input and output sides of a ZRIM lattice, after illumination of a TE polarized THz electromagnetic wave. In other words, by getting closer than a specific distance to the ZRIM lattice area from both input and output sides, which is called the interaction length, the wave profile will be affected significantly. Studying the field profile variation in the output side of the ZRIM lattice, we have considered two separate cascaded 2D PC-based ZRIM lattices in a THz waveguide with the same conditions and computed spatial phase shifts, and also the transmission and reflection coefficients versus the displacement between the two ZRIM lattices. This small limited distance led us to an almost 34° phase shift tuning between THz waves in two (multiple) THz waveguide systems.

Development of a New Lubricant Analysis Technique for Plant Facilities Using Terahertz Electromagnetic Wave Measurements

In this study, basic research was conducted on a new lubricant analysis technique to constantly monitor the deterioration state of rotating equipment and other components in plant facilities. The research method used terahertz electromagnetic waves, which are electromagnetic waves in the frequency range of 0.1 to 10 THz, the boundary region between light and radio waves. As a measurement method, we focused on the fact that terahertz electromagnetic waves are safe for the human body yet have excellent transmittance, and conducted experiments using terahertz time-domain spectroscopy (THz-TDS). In this study, THz-TDS measurements were performed on artificially degraded lubricating oil to verify the possibility of detecting degradation factors and separately identifying each degradation factor. As a result, it was possible to detect water and iron powder and to identify them separately using the transmittance of THz electromagnetic waves obtained from the obtained time waveforms and the standard deviation ratio of the peak intensity values of THz waveforms. In addition, the detection and separation of iron powder, water, and antioxidants were possible using the attenuation of terahertz electromagnetic waves obtained from the frequency waveforms obtained by Fourier transforming the time waveforms. These results suggest that terahertz electromagnetic waves can be used to detect iron powder, water, and antioxidants, which are factors involved in lubricant degradation, and that each degradation factor can be separated and identified by using terahertz electromagnetic waves.

Theory, simulation, fabrication, and characterization of Galois scattering plates for the optical and the THz spectral range

Scattering and scattering plates have a large diversity of applications. Scattering of optical and THz electromagnetic waves can be performed with Galois scattering plates, which had found applications in acoustics first (i.e., with sound waves in concert hall acoustics). For binary Galois scattering plates, the single scattering entities, i.e., mesas (for a binary 1) or voids (for a binary 0), have characteristic lateral dimensions of half the wavelength of the electromagnetic waves to be scattered. Their optimal height is a quarter of the wavelength for plates used in reflection. Meanwhile, not too elaborate lithographic techniques allow for the implementation of Galois plates for the THz range and even for the visible spectral range. We had reported on such scattering plates before. However, in this paper, also the mathematical concept is described and the fabrication technologies are emphasized. In contrast to the case of scattering plates with irregular surface morphologies, Galois plate scattering is not diffuse, but there are many scattering/diffraction orders.

Dynamical visualization of anisotropic electromagnetic re-emissions from a single metal micro-helix at THz frequencies

The capability for actual measurements—not just simulations—of the dynamical behavior of THz electromagnetic waves, including interactions with prevalent 3D objects, has become increasingly important not only for developments of various THz devices, but also for reliable evaluation of electromagnetic compatibility. We have obtained real-time visualizations of the spatial evolution of THz electromagnetic waves interacting with a single metal micro-helix. After the micro-helix is stimulated by a broadband pico-second pulse of THz electromagnetic waves, two types of anisotropic re-emissions can occur following overall inductive current oscillations in the micro-helix. They propagate in orthogonally crossed directions with different THz frequency spectra. This unique radiative feature can be very useful for the development of a smart antenna with broadband multiplexing/demultiplexing ability and directional adaptivity. In this way, we have demonstrated that our advanced measurement techniques can lead to the development of novel functional THz devices.

THz electromagnetic wave regulated dissolution of methane hydrate

Methane hydrate (so-called flammable ice) has many advantages such as wide distribution, large resource reserves, high energy density, being clean and pollution-free, etc. Thus, it has attracted much attention since it was discovered. Unfortunately, its exploration encounters many difficulties, which involve mainly with the dissolution process of caged methane hydrate. Therefore, in this work the specific effect of THz electromagnetic wave on decomposition of the hydrate is explored through molecular dynamics simulations. Analyzing the vibrational spectrum of the hydrogen-bond network in methane hydrate, no specific absorption peak is found in the bulk water. Applying a THz wave at this specific frequency to the methane hydrate, the original hydrogen-bond network is broken, the coordinate number of water molecules for the methane decreases, and ultimately the methane frees from the water cage. The <i>F</i><sub>4</sub> ordered parameters further validate the phase change from the crystal water to liquid water under the same THz field irritation. It is also proved that this peak absorption frequency has a remarkable superiority over other frequencies in decomposing the methane hydrate, hence it has specificity. Our findings support the feasibility of non-thermally dissolving methane hydrate, which promises to promote the exploitation efficiency and development of new energy sources in the future.

Tailoring THz antiferromagnetic resonance of NiO by cation substitution

Antiferromagnets generally have a quite high magnetic resonance, as known as the antiferromagnetic resonance, whose frequency goes up to the THz range. They are one of the few materials that can magnetically couple to THz electromagnetic waves and are therefore important materials for THz technologies. In this work, we demonstrate that the THz resonance properties, such as resonant frequency and the $Q$ factor, of antiferromagnetic NiO can be controlled over a wide range by substituting the $\mathrm{N}{\mathrm{i}}^{2+}$ cation with various different cations. Our discussion extends to the trends of how different substitute cations $\mathrm{M}{\mathrm{n}}^{2+}, \mathrm{L}{\mathrm{i}}^{+}$, and $\mathrm{M}{\mathrm{g}}^{2+}$ impact the resonant properties, which suggests a guideline for designing antiferromagnetic THz materials.

Amplified propagating plasmon in asymmetrical graphene periodic structure

The excitation and amplification of the propagating plasmons in a periodic active (with population inversion of charge carriers) graphene-based structure with dual grating-gate with an asymmetric unit cell is studied theoretically. Such structure transforms the normally incident THz electromagnetic wave into sustained or amplified unidirectionally propagating plasmon. This effect is caused by simultaneous excitation of radiative and ‘non-radiative’ plasmon modes at the same frequency.

Mixed Fano-SP resonant absorption of THz electromagnetic waves in a photonic resonator contacting with a metal film

In terahertz frequency region, we have investigated theoretically the correlation between spectra of a free photonic structure and that deposited on a metal for several models of metal. It was found that for quasi-normal incidence of p-polarized electromagnetic field the presence of metal generates narrow spectral wells in the middle of reflection windows existing in a free photonic crystal. Quite another manifestation of metal-resonator inter-influence takes place at incident angles exceeding the Brewster angle when reflection spikes coincide with modes of photonic crystal resonator and they are absent throughout the stopband areas. The effects are strongly depended on polarization, number of periods and angle of incidence.

Tunable dual-band terahertz metalens based on stacked graphene metasurfaces

Abstract In this paper, we propose and theoretically investigate a tunable stacked graphene metasurface, which can independently manipulate electromagnetic field at different terahertz frequency. By tuning the Fermi levels of graphene ribbons, the designed two-layers graphene ribbons can realize a required phase shift of ∼ 2 π for manipulating the terahertz wavefronts owing to the excitation of plasmon resonances at each layer of graphene ribbons. A reflective double-frequencies focusing metalens has been designed working at 3.5 THz and 7.0 THz. For the designed lens with focal lengths of 300 μ m , the focus depth of 3.5 THz and 7.0 THz electromagnetic wave (full width at half maximum along the Z direction) is 174. 7 μ m and 84 μ m , respectively. In addition, the resolution of focal points (full width at half maximum along the X direction) are close to the half-wavelength in the focusing plane, which are 48. 2 μ m and 21. 5 μ m respectively, demonstrating that the proposed metalens have superior performance. Furthermore, the focal length and offset distance of focal point of the lens can be tuned actively by changing gate voltages. The present graphene metasurface paves the way to engineering various potential applications for tunable, multiband, multifunctional metasurfaces.

Nondestructive evaluation on dispersion of steel fibers in UHPC using THz electromagnetic waves

Ultra-high performance concrete (UHPC), which has better mechanical properties and durability than reinforced concrete, can greatly reduce the weight of structures due to its high strength and reliability. So, it is very effective for the construction of high-rise buildings and long-span bridges. The mix design for UHPC is not only composed of traditional materials (i.e. cement, sand, and aggregate) but also includes binder and admixture. Moreover, steel fiber is necessary to improve ductility. Since the tensile strength of UHPC depends greatly on the direction of the steel fiber, it is important to confirm the dispersibility and orientation of the steel fiber. However, verification of the dispersibility of the steel fiber after curing is indirectly performed through destructive methods like strength tests through coring. Thus, for a better method of dispersibility confirmation, a more effective dispersion analysis technique is required. In this study, the dispersibility of steel fiber in UHPC was evaluated through tomography of UHPC using THz electromagnetic waves. These waves have both infrared straightness and microwave penetrability. Three UHPC specimens were fabricated with steel fiber and were tested with THz electromagnetic wave spectroscopy by experimentally scanning the specimen. From the experimental results, it was possible to obtain a 3D image of the steel fiber arrangement inside the specimen through scanning of the specimen. Also, through image analysis, the dispersibility of the steel fiber in each specimen was numerically derived. For the future, it is expected that the dispersion analysis technology proposed in this study will be applied as an automated nondestructive testing method for enhanced quality control.

Modeling of an Uncooled CMOS THz Thermal Detector With Frequency-Selective Dipole Antenna and PTAT Temperature Sensor

A thermal THz detector based on commercial CMOS technology working in room temperature is proposed. The THz electromagnetic wave is first selectively absorbed by an on-chip λ/4 dipole antenna realized in the metallization layer. The absorbed wave energy is then converted to Joule heat energy via a polysilicon resistor. The heat-generated temperature rise is finally detected by a proportional to absolute temperature sensor. The theoretical analysis and physical modeling of the detector including the mechanism of the electromagnetic energy absorption, the thermal conversion, and the electrical circuit response, are presented. The detectors at three typical THz frequencies of 1, 2.9, and 28.3 THz are designed in standard 0.18-μm CMOS technology and post-simulated to illustrate the detector's frequency-selective capability in the whole THz range. The simulated detector's voltage responsivity is 18.0 V/W at 1 THz, 18.9 V/W at 2.9 THz, and 18.6 V/W at 28.3 THz, respectively. The noise equivalent power is 1.7 μW/√Hz at the three frequencies.

Enhanced Terahertz Shielding of MXenes with Nano‐Metamaterials

AbstractTerahertz (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 (Ti3C2 MXene) thin films with nanoscale THz metamaterials are presented. Nanoscale slot antenna arrays with strong resonances at certain frequencies enhance THz electromagnetic waves up to three orders of magnitude in transmission, which in turn enormously increases the shielding performance in combination with MXene films. Drop‐casting of a colloidal solution of MXene (a few micrograms of dry material) can produce an ultrathin film (several tens of nanometers in thickness) on a slot antenna array. Consequently, THz waves strongly localized in the near‐field regime by the slot antenna undergo enhanced absorption through the film with a magnified effective refractive index. Finally, the combination of an ultrathin MXene film and a nano‐metamaterial shows excellent shielding performance in the THz range.

Coincidence of features of emitted THz electromagnetic wave power form a single Josephson junction and different current components

By applying a voltage to a Josephson junction, the charge in superconducting layers (S-layers) will oscillate. Wavelength of the charge oscillations in S-layers is related to external current in junction, by increasing the external current, the wavelength will decrease which cause in some currents the wavelength be incommensurate with width of junction, so the CVC shows Fiske like steps. External current throwing along junction has some components, resistive, capacitive and superconducting current, beside these currents there is a current in lateral direction of junction, (x direction). On the other hand, the emitted electromagnetic wave power in THz region is related to AC component of electric field in junction, which itself is related to charge density in S-layers, which is related to currents in the system. So we expect that features of variation of current components reflect the features of emitted THz power form junction. Here we study in detail the superconductive current in a long Josephson junction (JJ), the current voltage characteristics (CVC) of junction and emitted THz power from the system. Then we compare the results.Comparing the results we see that there is a good qualitative coincidence in features of emitted THz power and supercurrent in junction.

I – V characteristics and THz radiation properties of Bi2212 mesas

Large mesa structures composed of intrinsic Josephson junctions (IJJs) are expected to be one of a promising source of THz electromagnetic wave. In order to study the collective dynamics in large mesas with and without the influence of self-heating effect, two types of mesa structures are fabricated. One is a double-mesa structure which enables the non-uniform bias current distribution to examine the heat-flow in large mesas. We find that the current lead geometry strongly affects the collective switching of IJJs into resistive state even if the number of IJJs in the mesas is the same. Another is a standard rectangular mesa structure used in the emission experiments. In this mesa, we observe THz radiation from IJJs biased at the low bias region, where the self-heating effect is almost negligible, on inner branches of multiple I – V structures and find that all of observed intense inner-branch emissions correspond to the same cavity resonance mode.

Low Power 0.15 THz Wave Can Obviously Influence Human Blood Cycle Dynamics

BACKGROUND: With the development of modern information technology, the application demand of high frequency electromagnetic wave is growing, especially in THz (1012 Hz) frequency domains. According to quantum mechanics, THz wave has both volatility and particle feature, but its influence to human body has not been well studied yet. OBJECTIVE: In order to research the influence of THz electromagnetic wave to human body physiological activity. METHODS: We used a 0.15T THz source whose power is lower than 200μW to radiate volunteers for 204 person-times. We found that the blood cycle dynamics of human body could be changed obviously during radiation. RESULTS: Almost for all volunteers, a special PPG (photoPlethysmoGraphy) waveform had been observed in which D peak increased significantly. By using normalized DFT method, we found the power of second harmonic component in PPG signal rose dramatically. In contrast to the normal signal, the ratio of second harmonic component to first harmonic component rose from 26% to 237% of some volunteers. By using multi-scale entropy analysis, we found the complexity of the signal increased, which implies the improvement of body vitality. CONCLUSIONS: To our knowledge, this is the first report that even a low power terahertz electromagnetic wave can obviously influence human blood cycle dynamics.

The presence of two electron beams in a Cherenkov maser and their different behavior for generation and amplification of THz electromagnetic waves

The wave propagation in a cylindrical metallic waveguide including a dielectric tube is investigated. Two electron beams with opposite velocities are injected in the system as energy sources. It is shown that one of the electron beams is responsible for Cherenkov radiation, the other one is as the stabilizer. The dispersion relation of the waves, impedance of the waves, operating frequency of the system and time growth rate of THz waves are investigated. The effects of relative permittivity constant of dielectric tube, the geometrical dimensions, and the accelerating voltage on time growth rate are investigated. The effective factors on the frequency spectra of the waveguide will be presented too. It is obtained that the time growth rate of the waves increases with increasing the dielectric permittivity and thickness of the dielectric tube. In addition, with increasing the accelerating voltage the time growth rate has opposite behavior in some of the branches of the dispersion graphs. The power obtained in the excitation process for one branch of the dispersion graphs is presented. The graph of variations of transported power with respect to the wave frequency is plotted.

Superheterodyne Amplification for Increase the Working Frequency

The amplification of microwaves in n-GaAs films has been widely studied. On the other hand, using nonlinear parametric effects in microwave, millimeter, and THz ranges has a large potential. In this paper the resonant nonlinear phenomena are investigated in active n-GaAs semiconductor and in films on its base. The phenomena are the nonlinear interactions of space charge waves, including the frequency multiplication and mixing, and the three-wave interaction between two THz electromagnetic waves and a single space charge wave. This three-wave interaction results in the superheterodyne amplification of THz waves. The electron velocity in GaAs is the nonlinear function of an external electric field. If the bias electric field is more E0>Ecrit ≈3KV/cm , it is possible to obtain a negative differential mobility (NDM and space charge waves). The space charge waves have phase velocity of electrons equal to v0=v(E0), E0=V0/Lz , where V0 is the voltage, producing the bias electric field E0 in GaAs film. The superheterodyne amplification and the multiplication of microwaves are very promising for building active sensors in telecommunications system, radiometers, and radio telescopes. The superheterodyne mechanism has an advantage related to decreasing noise because of increasing of frequency in the process of amplification. It is used in the process of amplification of longitudinal space charge waves that in turn causes the transfer of energy from longitudinal wave into transverse one with increasing frequency. This is realized due to parametric coupling of two transverse waves and a single space charge wave in GaAs.