A5089609474- Terahertz technology and applications
- Metamaterials and Metasurfaces Applications
- Photonic Crystals and Applications
- Plasmonic and Surface Plasmon Research
- Photonic and Optical Devices
- Advanced Antenna and Metasurface Technologies
- Microwave Engineering and Waveguides
- Antenna Design and Analysis
- Superconducting and THz Device Technology
- Gyrotron and Vacuum Electronics Research
- Spectroscopy and Laser Applications
- Phase-change materials and chalcogenides
- Acoustic Wave Resonator Technologies
- Millimeter-Wave Propagation and Modeling
- Semiconductor Quantum Structures and Devices
- Plant and animal studies
- Thermal Radiation and Cooling Technologies
- ZnO doping and properties
- Topological Materials and Phenomena
- Semiconductor Lasers and Optical Devices
- Ferroelectric and Negative Capacitance Devices
- Optical Coatings and Gratings
- Antenna Design and Optimization
- MXene and MAX Phase Materials
- Gold and Silver Nanoparticles Synthesis and Applications
Shinshu University
2017-2024
Osaka University
2012-2024
Nara Medical University
2022
Ōtani University
2017-2018
Institute for Laser Technology
2007-2017
University of the Philippines Diliman
2016-2017
Fukuda Denshi (Japan)
2017
O.Ya. Usikov Institute for Radiophysics and Electronics
2017
University of Fukui
2017
Hiroshima University
2012
We fabricated a terahertz wire-grid polarizer consisting of micrometer-pitch Al grating on Si substrate by photolithography and wet etching. The ratio TM TE transmittances (extinction ratio) was over 35 dB at 0.5 THz. At the Brewster angle substrate, polarization transmittance wave through exceeded 95% extinction 45 approximately 1 has higher than conventional free-standing polarizers.
Abstract Microstructures in nature are ultrafine and ordered biological roles, which have attracted material scientists. Spirulina forms three-dimensional helical microstructure, one of remarkable features beyond our current processing technology such as lithography terms mass-productivity structural multiplicity. varies its diameter, pitch, and/or length against growing environment. This unique helix is suggestive a tiny electromagnetic coil, if composed electro-conductive metal, brought us...
Super-fine ink-jet (SIJ) printing technology is applied to the fabrication of terahertz metamaterials. A silver film fabricated using an SIJ printer with paste ink, and it confirmed that behaves as a good conductor in frequency region. Then, basic metamaterials such metal wire-grid structures split-ring resonators are printed on high-resistivity silicon substrates. The responses samples agree those expected from their structures. one ideal methods for fabricating owing its rapidity,...
Wire-grid polarizer sheets in the terahertz region have been fabricated on flexible substrates by nanoimprint technology. They show ideal polarization property frequency whereas cost is very low. Since wire pitch far smaller than wavelength, effective medium theory agrees well with experimental results. The shows possibility of further improvement properties selecting appropriate materials for grids.
Quasi-monodisperse dielectric particles organized in a periodic hexagonal network on an aluminum surface are exploited numerically and experimentally as single-layered near-perfect absorber the terahertz regime. Of particular interest titanium dioxide (TiO(2)) microspheres because of their large permittivity isotropic shape leading to Mie resonances with insensitive polarization. Absorption higher than 80% at normal incidence covering two distinct ranges frequencies is demonstrated...
Abstract With rapid advances occurring in terahertz (THz) radiation generation techniques, the interaction between matter and intense THz fields has become an important research topic. Among different types of sources, free electron laser (FEL) is a promising experimental tool that expected to pave way for new forms material processing, control phase transitions, serve as test bench extreme operating conditions high-speed small-size electrical magnetic devices through exploitation strong...
We demonstrate terahertz pulse generation from silver nanoparticle ink, originally developed for printed electronics, under irradiation by femtosecond laser pulses. Using metal metallic nanostructures can be easily made in a large area without lithographic techniques. Terahertz pulses were emitted the baked having spontaneously formed of ∼100 nm. From results baking temperature dependence and polarization measurement, is attributed to nonlinear induced enhanced local fields around these...
We re-examine the dominant factors of memory window (MW) and reliability HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeFET using a new technique to extract both spontaneous polarization (Ps) interface trap charges (Qt) by one-time current measurement an during operation. characteristics are strongly affected unstable Qt (unrelated ferroelectric) which causes Vth instability just after programming, stable Q1 compensates most...
Substantial enhancement of terahertz magnetic near field achieved by the combination a tapered metallic waveguide and micro-split-ring resonator is demonstrated. The probed directly via magneto-optic sampling with Tb3Ga5O12 crystal. incident wave half-cycle waveform generated using pulse-front tilting method. at resonant frequency enhanced more than 30 times through resonator. peak amplitude damped oscillation in time domain up to 0.4 T. can be tuned adopting different designs. mechanism...
Abstract Terahertz (THz)-transmission modulation through the Si substrate coated with four π-conjugated materials under various laser light irradiation conditions was investigated using THz time-domain spectroscopy. Two of low molecules, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), two polymer materials, poly[5-(2-ethylhexyloxy)-2-methoxycyanoterephthalyliden] (MEH-CN-PPV) poly(benzimidazobenzophenanthroline) (BBL), were...
We report the strong yellow emission of bulk ZnO single crystals irradiated with high-power gyrotron beam. Hydrothermally grown high conductivity are at room temperature up to 60-W output a sub-terahertz wave source. During irradiation, high-conductivity exhibit intense emissions peak around 2 eV (600 nm) and longer-wavelength tail. The sample temperatures were also elevated from above 1000 K by irradiation. However, when heated 1250 using heater without do not similar visible emissions....
We demonstrate a sensor card with cholesteric liquid crystals (CLCs) for terahertz (THz) waves generated from nonlinear crystal pumped by table-top laser. A beam profile of the THz is successfully visualized as color change without additional electronic devices, power supplies, and connecting cables. Above density 4.3 mW/cm2, approximate diameter measured using hue image that digitalized picture card. The low in cost, portable, suitable various situations such imaging alignment systems.
We proposed and demonstrated terahertz (THz) pulse detection by means of multilayered GeTe/Sb2Te3 phase-change memory materials that are also known as a multilayer topological insulator–normal insulator (MTN) system. THz time-domain spectroscopy measurement was performed for MTN films with different repetitions well conventional as-grown Ge–Te–Sb (GST) alloy film. It found MTNs absorb waves the absorption coefficient depends on number layers, while GST film almost transparent waves. Simple...
Electron photoemission and ponderomotive acceleration by surface enhanced optical fields is considered as a plausible mechanism of terahertz radiation from metallic nanostructures under ultrafast laser excitation. To verify this mechanism, we studied experimentally emission an array gold nanorods illuminated intense (~10-100 GW/cm2) femtosecond pulses different central wavelengths (600, 720, 800, 1500 nm). We found for the first time that order dependence fluence on intensity is,...
Three-dimensional bulk metamaterials that operate in the terahertz (THz) frequency range were fabricated by stacking 100 two-dimensional sheets containing metallic split-ring resonators (SRR) on thin polyethylene terephthalate film substrates. The THz magnetic resonance for incident field perpendicular to plane of SRR structure was measured. We also investigated dependence resonant strength metal thickness.
Terahertz (THz) transmission modulation through copper phthalocyanine (CuPc)-coated Si under various laser light irradiation conditions was investigated using THz time-domain spectroscopy. The charge carrier transfer from to CuPc is crucial for photo-induced metallization, and the thickness of layer a critical parameter achieving high density metallization. Transmission split-ring resonator array metamaterial, fabricated on CuPc-coated Si, can be efficiently modulated by irradiation. Our...
We demonstrate a new method to detect terahertz (THz) power using temperature-supersensitive capsulized cholesteric liquid crystal film based on the thermochromic and thermodiffusion effect, which is clearly observed. A quantitative visualization of THz intensity up 4.0 × 103 mW/cm2 presented. The diameter color change area linearly dependent radiation above 0.07 mW in steady state. Moreover, can be detected for 1 sec with parabolic relation area. meter robust, cost-effective, portable, even...
Absorption spectra of polycrystalline L-, D-, and DL-tartaric acid have been measured by terahertz time domain spectroscopy (THz-TDS). Different absorption bands are observed for its enantiomers (L- D-tartaric acid). This result shows that the THz-TDS can be used distinguishing between Moreover, partial least square (PLS) found to improve quantitation L-tartaric in L- mixture THz-TDS.
In this work, shape-dependent mid-infrared properties of novel split ring resonator (SRR) metamaterials composed single-walled carbon nanotube (CNT) forest are investigated. The introduction the gap and dip shape to closed geometry reduced total reflectance by 15%, due generation circular currents LC resonances in SRRs. increase SRR height IR 25%. Unique one-dimensional anisotropic electric photonic CNTs, combined with an artificial refractive index induced circuits, will stimulate...
We present the recent progress in HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -based ferroelectric FET (FeFET) and tunnel junction (FTJ) memory towards low-power high-density storage AI applications. A huge amount of interface trap charges coupled to spontaneous polarization significantly alters operating model improvement guideline FeFET irrespective elements doped into . Performance reliability in-memory reinforcement learning...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation K. Kan, J. Yang, A. Ogata, S. Sakakihara, T. Kondoh, Norizawa, I. Nozawa, Toigawa, Y. Yoshida, H. Kitahara, Takano, M. Hangyo, R. Kuroda, Toyokawa; Radially polarized terahertz waves from a photoconductive antenna with microstructures. Appl. Phys. Lett. 3 June 2013; 102 (22): 221118....
Optical switching of the spectrum and polarization terahertz radiation from split-ring resonator-loaded photoconductive antennas has been demonstrated. The is based on sensitivity resonance a resonator substrate to change in capacitance induced by optical pulse irradiation. spectral characteristics are discussed terms coupling between electric dipole pump laser eigenmodes resonators.
Transmission spectra of near-self-complementary metallic checkerboard patterns (MCPs) exhibit a drastic change when the metal squares are brought into contact with each other from noncontact state. samples, which fabricated by printing technology, show rather gradual systematic changing nominal square size while keeping period because randomness naturally introduced limited accuracy printer. The have transmission-invariant frequencies, means that superposition two types spectra, ratio...
We establish an accurate picture of cycling degradation in HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -FeFET based on the dynamics various kinds trap charges (e:electron/h+:hole, stable/unstable, program-induced/read-induced) revealed by fast charge centroid analysis. A part e trapped at /SiO interface, which is unrelated to ferroelectricity and unstable before degradation, becomes unrecoverable after cycling. By calculating its...