A5025871219- Photonic and Optical Devices
- Terahertz technology and applications
- Photonic Crystals and Applications
- Superconducting and THz Device Technology
- Optical Coatings and Gratings
- Laser Material Processing Techniques
- Metamaterials and Metasurfaces Applications
- Plasmonic and Surface Plasmon Research
- Microwave Engineering and Waveguides
- Radio Astronomy Observations and Technology
- Advanced Fiber Laser Technologies
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Orbital Angular Momentum in Optics
- Particle accelerators and beam dynamics
- Laser-Matter Interactions and Applications
- Semiconductor Quantum Structures and Devices
- Ocular and Laser Science Research
- Spectroscopy and Laser Applications
- Astronomy and Astrophysical Research
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Semiconductor Lasers and Optical Devices
- Advanced Antenna and Metasurface Technologies
- Magneto-Optical Properties and Applications
The University of Tokyo
2016-2025
Shimadzu (Japan)
2023
Graduate School USA
2018-2021
Japan Aerospace Exploration Agency
2020
Institute of Space and Astronautical Science
2020
Japan Science and Technology Agency
2009-2020
Institut d'Astrophysique Spatiale
2018-2020
Université Paris-Sud
2018-2020
Centre National de la Recherche Scientifique
2018-2020
Stockholm University
2020
Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of 20th Century, radiation, then referred to as sub-millimeter wave or far-infrared was mainly utilized by astronomers some spectroscopists. Following development laser time-domain spectroscopy in 1980s 1990s field THz science technology expanded rapidly, extent that it now touches many areas from fundamental 'real world' applications....
Abstract Active modulation of the polarization states terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In region, lack a modulator similar to photoelastic in visible range hampers expansion spectroscopy. A chiral metamaterial has huge optical activity unavailable nature; nevertheless, its still challenging. Here we demonstrate...
We demonstrate circularly polarized light emission from InAs quantum dots embedded in the waveguide region of a GaAs-based chiral nanostructure. The observed phenomenon originates due to strong imbalance between left- and right-circularly components vacuum field results degree polarization as high 26% at room temperature. A circular anisotropy modes inside nanostructure is visualized using numerical simulation. simulation agree well with experimental results.
Application of coherent light–matter interactions has recently been extended to the ultrafast control magnetization. An important but unrealized technique is manipulation magnetization vector motion make it follow an arbitrarily designed multidimensional trajectory. Here we demonstrate a full two-dimensional magnetic oscillations in antiferromagnetic NiO with pair polarization-twisted femtosecond laser pulses. We employ Raman-type nonlinear optical processes, wherein are impulsively induced...
The discrete rotational symmetry of nanostructures provides a powerful and simple guiding principle for designing the second-harmonic generation process in nonlinear metamaterials. We demonstrate that, achiral with threefold symmetries, circularly polarized fundamental beam produces countercircularly beam. In this case, polarization state second harmonic is determined very manner. also how symmetries metamaterials manifest themselves SHG selection rules.
Deep-ultraviolet (DUV) light is essential for applications including fabrication, molecular research, and biomedical imaging. Compact metalenses have the potential to drive further innovation in these fields, provided they utilize a material platform that cost-effective, durable, scalable. In this work, we present aluminum nitride (AlN) as an efficient solution DUV applications. These metalenses, with thickness of only 380 nm, deliver focusing imaging capabilities close theoretical...
Single-layer absorbers composed of sintered planar hexagonal ferrites were developed. The have 50/spl sim/90% relative bandwidth at microwave frequencies. broadband characteristics successfully analyzed by a quarter-wavelength resonator model, which took into account both wavelength reduction due to 1//spl radic/(/spl epsiv//sub r//spl mu//sub r/) and resonant frequency shift depending on tan /spl delta//sub mu//, where r/ are permittivity permeability, respectively, for the material.
We propose and demonstrate polarization rotation of a terahertz (THz) electromagnetic wave by using two-dimensional gratings consisting two displaced layers gold film with complimentary chiral patterns four-fold symmetry. develop time domain THz polarimetry method three wire grid polarizers distinguish optical activity from anisotropy. obtain the isotropic free birefringence structures. Results indicate possibility controlling artificial structures fabricated thin metal films.
We propose and demonstrate a method for generating broadband terahertz (THz) vortex beams. convert THz radially polarized beam into via achromatic polarization optical elements waves characterize the topological charge of generated by measuring spatial distribution phase wave at its focal plane. For example, uniform +1 is achieved over wide frequency range. also that sign can be easily controlled. By utilizing orbital angular momentum beam, these results open new technologies sensing,...
We report the investigation of a strong interband photon drag effect in multilayer graphene leading to efficient emission terahertz radiation. The obtained photoresponse layers exhibits peculiarities fundamentally predicted for free carrier transport two-dimensional electronic systems. Owing significant light absorption gapless graphene, where each absorbed produces an electron-hole pair with highest possible kinetic energy, mechanism provides possibility achieve conversion into broadband...
We propose and demonstrate a simple method for cylindrical vector beam generation in the terahertz frequency region using optical rectification segmented nonlinear crystals with threefold rotational symmetry. used GaP(111) plates to generate beam, obtained clear evidence of camera. By this method, broadband can be generated, radial azimuth modes easily switched. also report on direct observation longitudinal electric field components at focal point time-domain spectroscopy technique.
We propose an electrostatically actuated spiral structure as a metamaterial for circularly polarized light in the terahertz (THz) frequency range. An array of planar structures was fabricated with micro electro mechanical system technology, and geometry can be changed by electrostatic actuation. The actuation transforms spirals into three-dimensional helices, resulting optical activity which differential polarization response material depends on whether incident is left- or right-circularly...
For the first time, 3D printed metal-pipe rectangular waveguides (MPRWGs) have been demonstrated in WM-380 (500–750 GHz) and WM-250 (750 GHz–1.1 THz) waveguide bands. The ultra-high spatial resolution offered by new RECILS additive manufacturing technology enables precision fabrication of these prototype MPRWGs at such high frequencies. This enabling avoids need for access to expensive microfabrication resources and, thus, opens up terahertz spectrum low-cost manufacture passive components.
Light-field-driven processes occurring under conditions far beyond the diffraction limit of light can be manipulated by harnessing spatiotemporally tunable near fields. A tailor-made carrier envelope phase in a tunnel junction formed between nanogap electrodes allows precisely controlled manipulation these processes. In particular, characterization and active control fields are essential for advancing elaborate light-field-driven at atomic-scale. Here, we demonstrate that desirable...
Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application future satellite CMB polarization experiments. LiteBIRD is most advanced phase among such satellites, targeting its launch Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs focal planes reflective low-frequency and refractive medium-and-high-frequency...
Terahertz (THz) imaging has a strong potential for applications because many molecules have fingerprint spectra in this frequency region. Spectroscopic the THz region is promising technique to fully exploit characteristic. However, performance of conventional techniques restricted by requirement multidimensional scanning, which implies an image data acquisition time several minutes. In study, we propose and demonstrate novel broadband spectroscopic method that enables real-time using...
We have developed an electro-optic (EO) sampling method with polarization modulation of probe pulses; this allows us to measure the direction a terahertz (THz) electric-field vector precision 0.1 mrad in data acquisition time 660 ms using 14.0-kHz repetition rate pulsed light source. Through combination THz time-domain spectroscopy technique, time-dependent two-dimensional electric field was obtained. used photoelastic modulator for probe-polarization and (111)-oriented zincblende crystal as...
Terahertz (THz) cameras comprising an uncooled micro-bolometer array have been developed for simple THz imaging, and the improvement of their sensitivity is one important issues. We fabricated a new with resonant cavity structure real-time camera, alongside method evaluating across wide range frequency region. The dependence camera measured in 0.5-2.0-THz taking polarization into account. It was found that effectively increased and, actually, by order magnitude achieved below 1 THz. much...
Abstract Methylammonium lead iodide is a benchmark hybrid organic perovskite material used for low-cost printed solar cells with power conversion efficiency of over 20%. Nevertheless, the nature light–matter interaction in perovskites and exact physical mechanism underlying device operation are currently debated. Here, we report room temperature, ultrafast photocurrent generation, free-space terahertz emission from unbiased induced by femtosecond light pulses. The polarization dependence...
Abstract Light manipulation and control are essential in various contemporary technologies, as these technologies evolve, the demand for miniaturized optical components increases. Planar-lens such metasurfaces diffractive elements, have gained attention recent years their potential to dramatically reduce thickness of traditional refractive systems. However, fabrication, particularly visible wavelengths, involves complex costly processes, high-resolution lithography dry-etching, which has...