A5019084584- Terahertz technology and applications
- Photonic and Optical Devices
- Optical Coatings and Gratings
- Microwave Engineering and Waveguides
- Photonic Crystals and Applications
- Gyrotron and Vacuum Electronics Research
- Spectroscopy and Laser Applications
- Particle Accelerators and Free-Electron Lasers
- Acoustic Wave Resonator Technologies
- Allergic Rhinitis and Sensitization
- Advanced Chemical Sensor Technologies
- Plasmonic and Surface Plasmon Research
- Advanced Electron Microscopy Techniques and Applications
- Laser-Matter Interactions and Applications
- Crystallography and Radiation Phenomena
- Superconducting and THz Device Technology
- Radiomics and Machine Learning in Medical Imaging
- Semiconductor Quantum Structures and Devices
- Thermography and Photoacoustic Techniques
- Synthesis and properties of polymers
- Photoacoustic and Ultrasonic Imaging
- Near-Field Optical Microscopy
- Semiconductor materials and devices
- Millimeter-Wave Propagation and Modeling
- Microfluidic and Bio-sensing Technologies
Korea Atomic Energy Research Institute
2017-2024
Gwangju Institute of Science and Technology
2023-2024
Korea Photonics Technology Institute
2024
Korea Maritime and Ocean University
2014-2021
Budker Institute of Nuclear Physics
2020
In this study we report the first on terahertz (THz) transmission characteristics of a guided-mode resonance (GMR) filter made all-dielectric material. Two strong transverse electric (TE) modes, TE0,1 and TE1,1, one magnetic (TM) mode, TM0,1, were detected. The measured resonances can be explained by diffraction from grating surface GMR filter, guiding along inside (slab waveguide). Because two identical filters employed to overcome limited numbers, Q-factors TM0,1 modes as high 62.9, 71.0,...
A variable grating period made of quartz has been applied to fabricate a tunable guided mode resonance (TGMR) filter with transverse-electric (TE) and -magnetic (TM) modes in the terahertz (THz) region. We prepared three TGMR filters periods 5.0, 3.3, 1.7 μm/mm over length filter. For 5.0 μm/mm, resolution frequency shift TE0,1, TE1.1, TM0,1 was 3.6, 4.0, 3.4 GHz/mm, respectively. With metal slit spacing 2 mm located front filter, movable range 24 mm, could be shifted up 87, 96, 82 GHz,...
Abstract In this paper, we propose a terahertz (THz) guided-mode resonance (GMR) notch filter made of monolithic polyethylene terephthalate (PET) film, which has monolayer grating structure. The proposed configuration shows both polarization-dependent and polarization-independent characteristics for the incident THz wave depending on rotation angle second film. When is 0°, filtering strength (transmittance) at frequency changes from 0.4 (0.996) to 99.0% (0.010) according polarization....
We designed and fabricated a novel terahertz (THz) otoscope to help physicians diagnose otitis media (OM) with both THz diagnostics conventional optical diagnostics. verified the potential of this tool for diagnosing OM using mouse skin tissue human tympanic membrane samples prior clinical application.
We propose an all-dielectric single-layer guided-mode resonance filter (GMRF) operating in the high-frequency terahertz (THz) region. For fabrication of thin gratings to achieve strong region, refractive index and absorption must be small, while tensile strength high. Cyclic olefin copolymer (COC) films have a lower than polyethylene terephthalate (PET) higher yield polytetrafluoroethylene (PTFE) films. Therefore, COC film was found suitable fabricate GMRF THz fabricated COC-based GMRFs with...
All-dielectric binary gratings, with and without slab waveguides, are designed to generate polarization-independent guided-mode resonance filters (GMRFs) operating in the THz frequency region using rigorous coupled-wave analysis (RCWA) method. The filling factor thickness of grating were adjusted have equal frequencies transverse electric (TE)- magnetic (TM)-polarized beams. single for a waveguide was obtained at 0.459 full width half maximum (FWHM) values 8.3 8.5 GHz TE TM modes,...
Guided-mode resonance (GMR) filters were implemented by combining a monolayer grating made of polyethylene terephthalate (PET) and slab waveguide (dielectric film) quartz, PET, Teflon. The terahertz (THz) GMRs measured simulated for films with thickness change from 0 to 500 µm. As the increased, transverse-electric (TE) mode such as TE0,1, TE1,1, TE2,1, TE3,1 appeared sequentially. Because magnitude frequency depend on films' absorption thickness, we applied in order sense film's film. When...
We propose a multilayer slab waveguide (SWG) to enhance the resonance of transmittance with guided-mode (GMR) filter. The characteristics GMR filter were studied in three types according method attaching grating film SWG, which consists 25 µm thick polyethylene terephthalate (PET) layers separated by air layers. depth SWG was improved over that monolayer because refractive index and absorption reduced. However, high Q-factor has large attenuation loss due material absorption, enhancement...
Abstract The deflection of charged particles is an intuitive way to visualize electromagnetic oscillation coherent light. Here, we present a real-time ultrafast oscilloscope for time-frozen visualization terahertz (THz) optical wave by probing light-driven motion relativistic electrons. We found the unique condition subwavelength metal slit waveguide preserving distortion-free waveform during its propagation. Momentary stamping wave, transversely travelling inside slit, on ultrashort wide...
We investigated the spectral property changes in anti-adhesion films, which were cross-linked and surface-modified through electron beam irradiation, using terahertz time-domain spectroscopy (THz-TDS). Polyethylene oxide (PEO), is a biocompatible biodegradable polymer, was main component of these films being manufactured for testing. The characteristics affected by porosity generated during freeze-drying compression processes sample preparation, this confirmed optical coherence tomography...
The experimental observation of femtosecond dynamics in atoms and molecules by stroboscopic technologies utilizing x ray or electron flashes has attracted much attention rapidly developed. We propose a feasible ultrafast diffraction (UED) technology with high brightness sub-10 fs temporal resolution. previously demonstrated UED system an overall resolution 31 using RF photoelectron gun 90° achromatic bending structure. This structure enabled bunch duration 25 low timing jitter less than 10...
Abstract Ultrafast electron diffraction (UED) has evolved to be a powerful tool for the study of structural dynamics with subpicosecond temporal resolution and subatomic spatial resolution. Recently, there have been intense research efforts toward femtosecond timing jitter stability improving UEDs, however, so far no work showing long‐term (e.g., >1 h) stable MeV‐level UED systems. In this article, comprehensive synchronization method, based on optical‐radiofrequency THz streaking, is...
We report on the highly sensitive terahertz measurement of a thin, dielectric layer using two channels formed by inserting single slit sheet in parallel-plate waveguides (PPWGs). When thin is applied to coat upper surface channel, resonance frequency caused two-channel PPWGs shifted as result layer's properties, including length, thickness, and refractive index. The measured tuning sensitivities (FTS) throughout 20-mm length are 2.41 -1.95 GHz/mm at open lower channels, respectively....
<title>Abstract</title> We investigated an asymmetric slab grating structure to achieve significant tuning of the quality (Q) factor for a leaky mode while minimizing frequency variation. This comprises two identical gratings placed on top and bottom waveguide, with one laterally shifted introduce asymmetry. Simulations demonstrate that lateral shifting induces extensive changes in Q-factor minimal variation, particularly near band-flip filling fraction because remains unaffected by...
Objective 
Achieving ultra-precise temporal resolution in ionizing radiation detection is essential, particularly positron emission tomography, where precise timing enhances signal-to-noise ratios and may enable reconstruction-less imaging. A promising approach involves utilizing ultrafast modulation of the complex refractive index, sending probe pulses to crystals will result changes picoseconds (ps), thus a sub - 10 ps coincidence time can be realized. Towards this goal, here, we aim...
Abstract In this study, terahertz time‐domain spectroscopy (THz‐TDS) is employed for the first time to explore characteristics of mono‐, bi‐, and tri‐layer graphene coated on guided‐mode resonance filters (GMRFs). Owing high quality‐factor (Q‐factor) resonances GMRF, proposed method significantly enhances depth variation by up 9.3, 5.1, 4.2 times at 0.58 THz in TE mode graphene, respectively, contrast conventional THz‐TDS methods relying amplitude 0.50 mode. Excellent agreement observed...
We used deep learning methods to develop an AI model capable of autonomously delineating cancerous regions in digital pathology images (H&E-stained images). By using a transgenic brain tumor derived from the TS13-64 cell line, we digitized total 187 H&E-stained and annotated these compile dataset. A approach was executed through DEEP:PHI, which abstracts Python coding complexities, thereby simplifying execution training protocols for users. employing Image Crop with Mask technique patch...
We investigated an asymmetric slab grating structure to achieve significant tuning of the quality (Q) factor for a leaky mode while minimizing frequency variation. This comprises two identical gratings placed on top and bottom waveguide, with one laterally shifted introduce asymmetry. Simulations demonstrate that lateral shifting induces extensive changes in Q-factor minimal variation, particularly near band-flip filling fraction because remains unaffected by shifting. The independence from...
Recently, optical fiber coupled terahertz (THz) transceiver module has been developed. The THz chip in the twin dipole antennas which are independently aligned by femtosecond laser beam using polarization maintaining (PM) fiber. measured pulse is 1 nA peak-to-peak amplitude, 1,000:1 signal-to-noise ratio, and 2.0 bandwidth when reflected metal surface.