A5103015641- Terahertz technology and applications
- Physics of Superconductivity and Magnetism
- Photonic and Optical Devices
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Laser Applications
- Superconducting and THz Device Technology
- Semiconductor materials and devices
- Plant and animal studies
- Magnetic and transport properties of perovskites and related materials
- Acoustic Wave Resonator Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Silicon Nanostructures and Photoluminescence
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Integrated Circuits and Semiconductor Failure Analysis
- GaN-based semiconductor devices and materials
- Thin-Film Transistor Technologies
- Advanced Chemical Physics Studies
- Gyrotron and Vacuum Electronics Research
- Advanced Condensed Matter Physics
- Plasmonic and Surface Plasmon Research
- Ga2O3 and related materials
- Photonic Crystals and Applications
- Luminescence Properties of Advanced Materials
- Quantum and electron transport phenomena
Osaka University
2015-2024
University of Warsaw
2023
Kyoto University
2023
Laboratoire de l'Intégration du Matériau au Système
2021
Yamashina Institute for Ornithology
2020
Institute for Laser Technology
2005-2017
Rice University
2016
Hiroshima University
2000-2013
Kōchi University
2009
Institute for Molecular Science
2001-2007
The crystallographic anisotropy in electromagnetic terahertz radiation from multiferroic BiFeO3 (100), (110), and (111) films suggests the ultrafast depolarization of ferroelectric order as a new mechanism emission. This implies that spontaneous polarization materials can be manipulated time scale picoseconds, thus paving way to data-storage devices based on nonvolatile memories.
We have proposed and developed a scanning laser terahertz (THz) near-field imaging system using 1.56 μm femtosecond fiber for high spatial resolution high-speed measurement. To obtain the two-dimensional (2D) THz images of samples, pulses are scanned over 2D emitter plate [DASC: 4'-dimenthylamino-N-methyl-4- stilbazolium p-chlorobenzenesulfonate] by galvano meter. In this system, wave locally generated at irradiation spots transmit through sample set on emitter, amplitude transmitted pulse...
Adsorption of gas molecules on the surface atomically layered two-dimensional (2D) materials, including graphene and transition metal dichalcogenides, can significantly affect their electrical optical properties. Therefore, a microscopic quantitative understanding mechanism dynamics molecular adsorption desorption has to be achieved in order advance device applications based these materials. However, recent theoretical calculations have yielded contradictory results, particularly magnitude...
We present a nonlinear optical crystal (NLOC)-based terahertz (THz) microfluidic chip with few arrays of split ring resonators (SRRs) for ultra-trace and quantitative measurements liquid solutions. The proposed operates on the basis near-field coupling between SRRs local emission point like THz source that is generated in process rectification NLOCs sub-wavelength scale. solutions flowing inside microchannel modify resonance frequency peak attenuation transmission spectra. In contrast to...
We employed a laser terahertz (THz) emission microscope (LTEM) as novel tool for evaluating solar cells. LTEM images are obtained by exciting polycrystalline silicon cell with femtosecond illumination and visualizing the local distribution of optical response. THz signals also provide various types information, such screening effect built-in electrical field near pn junctions. These results indicate that this technique can be used to evaluate photoelectric conversion efficiency dynamic...
The laser terahertz (THz) emission microscope (LTEM) is a unique inspection tool which can directly two-dimensionally map the THz pulse from variety of electric materials and devices. Thus, two-dimensional mapping yields various physical information by visualizing distributions field, supercurrent, ferroelectric domain structures, magnetic fluxes, etc. Based on techniques created for conventional LTEM, we have developed more highly functional imaging system, including scanning (near-field)...
Biosensing with terahertz (THz) waves has received large amounts of attention due to its potential detect the functional expression biomolecules in a label-free fashion. However, many practical challenges against diffraction limit THz and strong absorption into polar solvents still remain development compact biosensors. Here, we present non-linear, optical, crystal-based THz-microfluidic chip few arrays asymmetric meta-atoms, an elementary unit metamaterials, for measurement trace solution...
We report on a new roadblock which will limit the gate oxide thickness scaling of MOSFETs. It is found that statistical distribution direct tunnel leakage current through 1.2 to 2.8 nm thick oxides induces significant fluctuations in threshold voltage and transconductance when resistance becomes comparable poly-Si resistance. By calculating measured based multiple scattering theory, it shown device characteristics be problematic scaled down less than 1 nm.
The structural dependence of magnetization in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ thin films deposited on ${(\mathrm{La}\mathrm{Al}{\mathrm{O}}_{3})}_{0.3}{({\mathrm{Sr}}_{2}\mathrm{Al}\mathrm{Ta}{\mathrm{O}}_{6})}_{0.7}$ (001) substrate has been investigated the film thickness $(t)$ range $40--500\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. High-resolution x-ray-diffraction studies reveal a dependent transition from fully strained tetragonal phase for with...
Based on the successful result of fast heating a shell target with cone for beam injection at Osaka University in 2002 using PW laser (Kodama et al Nature 418 933), FIREX-1 project was started 2004. Its goal is to demonstrate fuel up 5 keV an upgraded beam. For this purpose, LFEX laser, which can deliver energy to10 kJ 0.5–20 ps pulse its full spec, has been constructed addition Gekko-XII system Institute Laser Engineering, University. It activated and became operational since 2009....
We investigate the nonlinear effect of a planar superconducting metamaterial made from niobium nitride (NbN) at terahertz frequencies. As variation incident intense field alters intrinsic conductivity in NbN, consequent giant amplitude modulation is observed due to strong nonlinearities. The high sensitivity chosen even allows observing behaviors various temperatures, but resonance induced by was distinct that heating effect. presented results illustrate clever implementation strongly...
Excitons play major roles in optical processes modern semiconductors, such as single-wall carbon nanotubes (CNTs), transition metal dichalcogenides, and 2D perovskite quantum wells. They possess extremely large binding energies (>100 meV), dominating absorption emission spectra even at high temperatures. The imply that they are stable, is, hard to ionize, rendering them seemingly unsuited for optoelectronic devices require mobile charge carriers, especially terahertz emitters solar cells....
Abstract Imaging with terahertz (THz) waves has been expected as a non-invasive/non-staining visualization tool for breast cancer margins during surgeries. Breast is generic name heterogeneous lesion comprising invasive adenocarcinoma, in situ most frequently the form of ductal carcinoma (DCIS) and benign tissues. Until now, THz imaging focused on adenocarcinoma; however, analysis DCIS hardly performed. One reasons that size an individual lesion, ranging from 50 to 500 µ m, typically much...
We have measured the dielectric properties of pulsed-laser-deposited SrTiO3 (STO) thin films by terahertz (THz) time-domain spectroscopy in frequency range from 80GHzto1.5THz at temperatures 20to290K. The dispersion constant STO show a clear Lorentzian oscillator behavior below 180K and softening ferroelectric soft mode takes place with decreasing temperature. Both eigen damping phonon peak nearly 110K that can be attributed to effect on Ti–O–Ti bending film due starting tilting oxygen...
A new scheme of optical rectification (OR) femtosecond laser pulses in a periodically poled lithium niobate (PPLN) crystal, which generates high energy and bandwidth tunable multicycle THz pulses, is proposed demonstrated. We show that the number oscillation cycles electric field therefore generated spectrum can easily smoothly be tuned from few tens GHz to by changing pump spot size on PPLN crystal. The minimal 17 smallest ever reported generation OR at room temperature. Similar case...
Being an atomically thin material, graphene is known to be extremely susceptible its environment, including defects and phonons in the substrate on which it placed as well gas molecules that surround it. Thus, any device design using has take into consideration all surrounding components, performance needs evaluated terms of environmental influence. However, no methods have been established date readily measure density distribution external perturbations a quantitative non-destructive...
We developed a scanning laser terahertz (THz) near-field reflection imaging system using fiber-coupled femtosecond source for high spatial resolution measurements without any sub-wavelength probes. In this system, THz wave pulses generated at the focusing spot in non-linear optical crystal interact with sample set on crystal. Using we obtained images of metallic structures ∼λTHz/34 (λTHz = 680 μm) and also observed paraffin-embedded human breast tissue several 10 μm size. These results...
A recently developed laser terahertz (THz) emission microscope (LTEM) is a new type of inspection tool for semiconductor integrated circuits by 2-D mapping THz excited femtosecond (fs) pulse. For high-resolution imaging, we demonstrate the combination hemispherical solid immersion lens (SIL) and an LTEM with transmission-type detection mode. Unlike reflective geometries, in which both probing fs pulses generated emissions utilize same optical components, transmission system enables...
We present the nonlinear response of superconducting niobium nitride (NbN) thin film and NbN metamaterial with different thicknesses under intense terahertz pulses. For film, nonlinearity emerges superconductivity is suppressed increasing incident electric field, suppression extent weakens as thickness increases from 15 to 50 nm. As variation in fields alters intrinsic conductivity NbN, a consequent remarkable amplitude modulation observed due strong nonlinearity. Absorbed photo density...
Abstract Far-UV light sources have attracted much attention for human-safe viral inactivation and bacterial disinfection. Due to large optical nonlinearity transparency this wavelength region, AlN is a promising material compact low-cost far-UV second harmonic generation (SHG) devices. In study, transverse quasi-phase-matched channel waveguide with vertical polarity inversion was designed fabricated. From spectra pump power dependence of an SH intensity, SHG via the largest nonlinear tensor...
Low temperature STM/STS observation for BSCCO single crystal was carried out to investigate an intrinsic superconducting gap state of CuO 2 layer. The STM revealed a mid-level-layer between the top and bottom BiO surfaces half unit cell in c-axis direction. STS study on this mid-level surface brought reproducible definite structure which shows finite region with low conductance level about 5%, also nature wide range parameter Δ max /Δ min ∼4 ∼10 meV. This is considered be more direct...