A5002960715- Terahertz technology and applications
- Semiconductor Quantum Structures and Devices
- Photonic and Optical Devices
- Superconducting and THz Device Technology
- Spectroscopy and Laser Applications
- Photonic Crystals and Applications
- Luminescence Properties of Advanced Materials
- Semiconductor Lasers and Optical Devices
- Nanowire Synthesis and Applications
- Silicon Nanostructures and Photoluminescence
- Solid State Laser Technologies
- ZnO doping and properties
- Quantum and electron transport phenomena
- Semiconductor materials and interfaces
- Advanced Semiconductor Detectors and Materials
- Plasmonic and Surface Plasmon Research
- Acoustic Wave Resonator Technologies
- Atomic and Subatomic Physics Research
- Gas Sensing Nanomaterials and Sensors
- Radiation Detection and Scintillator Technologies
- Gyrotron and Vacuum Electronics Research
- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- Nuclear Physics and Applications
- Quantum Dots Synthesis And Properties
University of the Philippines Diliman
2015-2024
University of the Philippines System
2003-2021
Osaka University
2006-2020
University of Fukui
2011-2019
Institute for Laser Technology
2006-2010
Tohoku University
2008-2010
Fukuda Denshi (Japan)
2010
Japan Synchrotron Radiation Research Institute
2010
Tokuyama (Japan)
2008
Institute for Molecular Science
2005-2007
A hollow-core microstructured polymer optical fiber was analyzed in the terahertz (THz) region. Spectral analysis of time domain data shows propagation THz waves both and cladding with a delay ~20 ps. The frequency range shift transmission bands between different sized waveguides suggested photonic bandgap or resonant guidance. Finite-difference calculations agree relatively well to experimental results. Propagation losses were estimated be as low 0.9 dB/cm.
We experimentally demonstrate an efficient electro-optic sampling scheme based on Cherenkov phase matching of broadband terahertz radiation with 800-nm femtosecond probe beam in a 0.5 mm-thick LiNbO3 crystal coupled to Si prism. The signal from Cherenkov-phase-matched is found be comparable that 4 ZnTe using collinear matching. technique can achieved any wavelength and hence has advantage over the method.
A new electro-optic (EO) sampling scheme, which we refer to as "heterodyne EO sampling", for detection of pulsed terahertz (THz) waves is proposed and experimentally demonstrated. In this heterodyne the intensity change in optical probe pulse induced by a THz field nonlinear crystal measured without any polarization optics. Applied combination with non-collinear Cherenkov velocity matching technique, method allows one detect efficiently easily using simpler setup compared conventional...
Experimental results are presented on the neutron scintillating properties of a custom-designed Pr3+ (praseodymium)-doped lithium (Li) glass. Luminescence was observed at 278 nm wavelength, originating from 5d-4f transition. Time-resolved measurements yielded about 20 ns decay times for ultraviolet and x-ray excitation while much faster 6 were alpha particle excitation. Actual time-of-flight data in laser fusion experiments GEKKO XII facility Institute Laser Engineering, Osaka University...
For pump and probe experiments in x-ray free-electron laser (XFEL) facilities, accurate timing synchronization between short-wavelength femtosecond pulses from XFELs short optical other light sources is required. this purpose, the response time of a hydrothermal-method-grown ZnO improved by over one order magnitude via intentional iron ion doping. The fluorescence rise- decay-time constants are measured to be less than 10 100 ps, respectively. Owing its intense even for single pulse XFEL...
We report on the intense terahertz emission from InAs/GaAs quantum dot (QD) structures grown by molecular beam epitaxy. Results reveal that QD sample was as high 70% of a p-type InAs wafer, most semiconductor emitter to date. Excitation wavelength studies showed due absorption in strained undoped GaAs, and corresponds two order-of-magnitude enhancement. Moreover, it found multilayer QDs emit more strongly compared with single layer sample. At present, we ascribe radiation huge strain fields...
We report the vacuum ultraviolet luminescence characteristics of a micro-pulling down method grown Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> :LiCaAlF <sub xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> . Emission at 163 nm with lifetime 1.3-μs observed F xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser (157-nm) pumping. This is one shortest emission wavelengths reported from rare-earth doped fluoride room temperature.
Vacuum ultraviolet fluorescence from Czochralski method-grown Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> :LaF <sub xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> excited by 290 nm femtosecond pulses a Ti:sapphire laser is reported. Peak emission at 175 with 7 ns lifetime observed. This decay time would be one of the fastest among solid-state, inorganic scintillators. Laser in VUV region may also achievable pumping existing...
Terahertz (THz) emission from GaAs-AlGaAs core-shell nanowires (CSNW) on silicon (100) substrates was investigated using THz time-domain spectroscopy. The applied magnetic field polarity dependence strongly suggests that originated photo-carriers in the CSNWs. Optical excitation of yielded a wider bandwidth compared with just GaAs core material. This result is currently attributed to faster carrier lifetimes AlGaAs shell. spectral data are supported by time-resolved photoluminescence studies.
In this paper, we propose and experimentally demonstrate noncollinear EO sampling of terahertz pulses with a femtosecond fiber laser in cm-thick GaAs crystals. This technique provides more than an order magnitude improvement spectral resolution significant increase efficiency as compared to previously used collinear mm- sub-mm-thick The optimal incidence angle the probe beam on crystal is found be 42 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
The growth of low-temperature-grown GaAs (LTG-GaAs) on semi-insulating substrate with a 0.2 μm n-GaAs buffer demonstrated enhanced terahertz (THz) emission in reflection and transmission excitation geometries via time-domain spectroscopy. transient photocurrent the sample resulting from ultrafast yielded 215% 165% increase THz emission, respectively, as compared grown an undoped buffer. LTG-GaAs film exhibited significant its built-in field supported by calculations photoreflectance...
Nd3+:(La1-xBax)F3-x (x = 0.1) efficiently grown by the micro-pulling down method is explored. Transparency to 164 nm and broad fluorescence centered at 175 make it a novel vacuum ultraviolet scintillator potential tunable laser material with capability of short pulse amplification.
Details of the design and development a bright vacuum ultraviolet Seya–Namioka type spectrometer streak camera system with reflection-type input optics is presented. The has 40 mm by 45 holographic grating groove density 600 grooves/mm, linear dispersion 8 nm/mm, effective F-number 4.2. To eliminate loss light absorption, imaging unit uses Al MgF2 coated at least 80% reflection from 125–850 nm an 4. It equipped synchronized scan that can be tuned to 82 MHz slow speed measure up 2-MHz single...
We present the use of a "double optical pump" technique in terahertz time-domain emission spectroscopy as an alternative method to investigate lifetime photo-excited carriers semiconductors. Compared commonly employed pump-probe transient photo-reflectance, this non-contact and room temperature characterization allows relative ease achieving alignment. The was implemented evaluate carrier low temperature-grown gallium arsenide (LT-GaAs). values deduced from THz decay curves show good...
We report on increasing the sensitivity of electro-optic sampling detection terahertz pulses by using effect field enhancement in a tapered metallic waveguide. A thin Si prism, placed narrower section waveguide, is used to synchronize enhanced with probe laser pulse propagating LiNbO3 crystal attached obliquely cut end 40-µm-thick MgO-doped layer surface for guiding pulse. The developed structure demonstrates 20-fold higher than no-waveguide, Si-prism-coupled crystal.
A polymer-based, Cytop planar photonic crystal waveguide (PPCW) was designed for guiding terahertz radiation. Results indicate that the propagation and coupling losses in 0.2–1.1THz range are relatively small a sheetlike thickness design. Spectral analysis of transmission data reveals frequency selectivity PPCW. Calculations spatial distribution electric field through show evidence single-mode at 0.45THz central frequency. The highly transparent nature from deep ultraviolet to far infrared...
The azimuthal angle dependence in the terahertz radiation power of (100) InAs under 1T magnetic field is presented. Results show that although dominant mechanism surge current, azimuthal-angle-dependent due to nonlinear effect also observed. twofold symmetry p-polarized was modified a fourfold with transverse field. Moreover, results exhibited for s-polarized even no applied anisotropic intervalley scattering photocarriers tentatively proposed as origin quadrupole response and emission symmetry.
We describe the successful growth of a laser quality Ce3+:LiCaAlF6 crystal using micro-pulling down method. The is grown less than one gram raw material and pulling rate 0.1 mm/min. Ultraviolet emission at 290 nm with 23% slope efficiency 1 mJ pulse energy demonstrated from Brewster-cut crystal, which 30 mm in length 2 diameter. flexibility lower cost this technique will markedly reduce growing grade crystals.
Nd3+:(La1−x,Bax)F3−x(x=0.1) is efficiently grown by the micro-pulling-down method. Characterization of its optical properties reveals that it transparent in vacuum ultraviolet region with an absorption edge at around 180 nm. It has fluorescence centered 175 nm a bandwidth 12 and lifetime 6.1 ns as measured streak camera spectrometer combination. proposed to be suitable scintillator potential laser material.
β - Ba B 2 O 4 (BBO) was found to have huge birefringence in the 0.1–1.1THz frequency region. Polarized terahertz transmission spectroscopy revealed a Δn∕n value of about 0.12±0.02. This result could be related polarization-dependent absorption that observed at 0.65THz; close agreement with first principles-calculations, showing this due low-frequency phonon modes [B3O6]3-rings. These findings suggest utilization birefringent properties BBO for optical parametric devices including amplifiers...