Kiwon Moon

Kiwon Moon
Electronics and Telecommunications Research Institute | ETRI · Creative Research Center

Ph. D

About

59
Publications
5,711
Reads
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538
Citations
Additional affiliations
February 2000 - April 2005
Samsung Electro-Mechanics
Position
  • Senior Researcher

Publications

Publications (59)
Article
Full-text available
Terahertz (THz) technology offers unique see-through imaging capability for various non-destructive inspection applications. In this work, we implemented a broadband continuous-wave THz imaging system to study technical issues related to the see-through imaging, including frequency-dependent resolution, material loss, and interference-induced artif...
Article
Nondestructive THz imaging technology is a promising technology in several industrial applications such as process monitoring and quality control. To further popularize the application of this technique in the industry, we developed photonics-based devices such as a dual-mode laser, uni-travelling carrier photodiode, and Schottky-barrier diode that...
Article
Full-text available
Terahertz near-field microscopy (THz-NFM) could locally probe low-energy molecular vibration dynamics below diffraction limits, showing promise to decipher intermolecular interactions of biomolecules and quantum matters with unique THz vibrational fingerprints. However, its realization has been impeded by low spatial and spectral resolutions and la...
Article
We modified our 910-m long path THz system to increase the signal-to-noise ratio (S/N) with a nanostructure plasmonic THz transmitter (Tx) chip and a seven-mirror array reflector with 1 m diameter. When the THz pulse propagates the 910-m distance in the atmosphere, the S/N is up to 1170:1, which made the THz pulse measurable at a high water vapor d...
Article
Full-text available
A terahertz continuous wave system is demonstrated for thickness measurement using Gouy phase shift interferometry without frequency sweep. One arm of the interferometer utilizes a collimated wave as a reference, and the other arm applies a focused beam for sample investigation. When the optical path difference (OPD) of the arms is zero, a destruct...
Article
Rectifiers have been used to detect electromagnetic waves with very low photon energies. In these rectifying devices, different methods have been utilized, such as adjusting the bandgap and the doping profile, or utilizing the contact potential of the metal-semiconductor junction to produce current flow depending on the direction of the electric fi...
Article
Full-text available
Time-domain and frequency-domain terahertz (THz) spectroscopy systems often use materials fabricated with exotic and expensive methods that intentionally introduce defects to meet short carrier lifetime requirements. In this study, we demonstrate the development of a nano-photomixer that meets response speed requirements without using defect-incorp...
Conference Paper
With a vision of easily-accessible terahertz industrial applications, we are in pursuit of small and cost-effective terahertz technologies. Our various approaches for the enhanced performances, including arrayed devices and nano-based devices will be presented.
Conference Paper
Recently, nano-structures have been adopted for the photonics-based THz emitters and detectors to enhance their output power and detection sensitivity. The notable improvements have been attributed to the plasmon enhanced absorption. However, we found that the field enhancement at the extremities of the nano-structure dominates over the plasmon eff...
Article
Plasmonic field enhancement in terahertz (THz) generation is one of the recently arisen techniques in the THz field that has attracted considerable interest. However, the reported levels of enhancement of THz output power in the literature are significantly different from each other, from less than two times to about two orders of magnitude of enha...
Conference Paper
We successfully demonstrate a THz generation using an ytterbium (Yb)-doped mode-locked femtosecond fiber laser and a home-made low-temperature grown (LTG) InGaAs Photoconductive antenna (PCA) module for THz Time-domain spectroscopy (TDS) systems. The Yb-doped fiber ring laser consists of a pump laser diode (PLD), a wavelength division multiplexer (...
Article
Full-text available
We demonstrate a terahertz (THz) radiation using log-spiral-based low-temperature-grown (LTG) InGaAs photoconductive antenna (PCA) modules and a passively mode-locked 1030 nm Yb-doped fiber laser. The passively mode-locked Yb-doped fiber laser is easily implemented with nonlinear polarization rotation in the normal dispersion using a 10-nm spectral...
Article
Full-text available
We designed and fabricated a semiconductor optical amplifier-integrated dual-mode laser (SOA-DML) as a compact and widely tunable continuous-wave terahertz (CW THz) beat source, and a pin-photodiode (pin-PD) integrated with a log-periodic planar antenna as a CW THz emitter. The SOA-DML chip consists of two distributed feedback lasers, a phase secti...
Article
In this study, we design a compact terahertz (THz) reflection scanner with a scan rate of 20 frames/s. This scanner is based on a benzocyclobutene-embedded InGaAs Schottky barrier diode detector having a maximum responsivity of 300V/W at 250GHz and a minimum noise equivalent power of 38pW/Hz p. With this scanner, details such as sharp head and tail...
Conference Paper
By using nano-electrodes, the THz emission power was improved by four times and more than 50 times for the pulse and continuous-wave terahertz emitter. Comparisons are made in terms of local carrier dynamics.
Article
Full-text available
Photoconductive antennas with nano-structured electrodes and which show significantly improved performances have been proposed to satisfy the demand for compact and efficient terahertz (THz) sources. Plasmonic field enhancement was previously considered the dominant mechanism accounting for the improvements in the underlying physics. However, we di...
Conference Paper
Metallic nano-electrodes improve the emission efficiency of THz photo-conductive antennas. But the main enhancement mechanism has not been systematically studied. In this study, we experimentally compared the effect of plasmonic enhanced absorption and bias field enhancement at the apex of nano-fingers. We concluded that the bias field enhancement...
Article
An active terahertz (THz) wave hybrid grating structure of Au/Ti metallic grating on VO2/Al2O3 (0001) was fabricated and evaluated. In our structure, it is shown that the metallic gratings on the VO2 layer strengthen the metallic characteristics to enhance the contrast of the metallic and dielectric phases of a VO2-based device. Especially, the met...
Article
Our recent studies in regards of developing portable THz scanner for imaging and spectroscopy systems are presented. In the course, high power tunable continuous wave (CW) THz emitter and high sensitivity THz receiver platforms are presented. Those platforms can be realized with tunable optical beating source, broadband photomixer, arrayed photomix...
Article
Full-text available
In this study, inspired by the frequency-modulated continuous-wave (FMCW) method, an operation scheme of continuous-wave (CW) terahertz (THz) homodyne system is proposed and evaluated. For this purpose, we utilized the fast and stable wavelength tuning characteristics of a dual-mode laser (DML) as a beating source. Using the frequency-modulated THz...
Conference Paper
We successfully demonstrate a THz generation using low-temperature grown InGaAs photoconductive antenna pumped by an Yb-doped mode-locked femtosecond fiber laser. We achieved fast Fourier transform amplitude spectrum with a bandwidth of 1.5 THz.
Article
Combined with THz time-domain spectroscopy, THz near-field microscopy based on an atomic force microscope is a technique that, while challenging to implement, is invaluable for probing low-energy light-matter interactions of solid-state and biomolecular nanostructures, which are usually embedded in background media. Here, we experimentally demonstr...
Article
We demonstrate real-time continuous-wave terahertz (THz) line-scanned imaging based on a 1 × 240 InGaAs Schottky barrier diode (SBD) array detector with a scan velocity of 25 cm/s, a scan line length of 12 cm, and a pixel size of 0.5 × 0.5 mm2. Foreign substances, such as a paper clip with a spatial resolution of approximately 1 mm that is hidden u...
Article
A wire-grid polarizer based on VO2/Al2O3 (0001) is fabricated. It is experimentally confirmed that the polarizer controls the amplitude of the transmitted THz wave by changing the temperature. The device performance was estimated through degree of polarization (DOP), extinction ratio (ER), and the temperature dependence of field amplitude modulatio...
Article
Semiconductor devices based on photonics for the tunable continuous-wave THz generation and detection are explored. A tunable single-chip terahertz transceiver consists of beating source, broadband photomixer, and THz detector is developed. The realizable possibility of monolithically integrated single-chip THz transceiver which is main building bl...
Conference Paper
We fabricated a nano-gap electrode large area THz emitter and measured the THz emission using a femtosecond laser based THz time-domain spectroscopy system. As a result of adopting the large-area emitter structure, the optical power density was significantly reduced at the active region, and the emission power was improved by 20 times.
Conference Paper
A 1.3-µm dual-mode laser diode with an integrated semiconductor optical amplifier with high output power of over 80 mW has been developed as an optical beat source for a continuous wave terahertz system
Article
We have demonstrated a terahertz (THz) time-domain spectroscopy and imaging system using compact fiber-coupled THz modules. Using this THz spectroscopy system we have measured the absorption spectrum of water vapor in free space over 3 THz, as well as the refractive indices of various substrates such as Si, , and GaAs using the transfer-function me...
Article
A novel type of semiconductor beating source, a monolithically integrated dual-mode laser, and continuous-wave terahertz (THz) system adopting it will be investigated. The combined system of the beating source with broadbandantenna- integrated low-temperature-grown semiconductor photomixers shows the possibility of the realization of the cost-effec...
Article
In this letter, we present low-temperature grown GaAs (LTG-GaAs)-based photoconductive antennas for the generation and detection of terahertz (THz) waves. The growth of LTG-GaAs and the annealing temperatures are systematically discussed based on the material characteristics and the properties of THz emission and detection. The optimum annealing te...
Article
Terahertz (THz) waves have been exploited for the non-contact measurements of thickness and refractive index, which has enormous industrial applicability. In this work, we demonstrate a 1.3-μm dual-mode laser (DML)-based continuous-wave THz system for the real-time measurement of a commercial indium-tin-oxide (ITO)-coated glass. The system is compa...
Conference Paper
A simple and compact method of generating modulated beating signals from a dual-mode laser via bias modulation of integrated micro-heaters is proposed and successfully demonstrated. The proposed scheme will enrich the continuous-wave terahertz system applications.
Article
Full-text available
A novel buried photomixer for integrated photonic terahertz devices is proposed. The active region of the mesa-structure InGaAs photomixer is buried in an InP layer grown by metalorganic chemical vapor deposition (MOCVD) to improve heat dissipation, which is an important problem for terahertz photomixers. The proposed photomixer shows good thermal...
Conference Paper
The photomixers enables continuous-wave, frequency-tunable terahertz (THz) emitter and detector by using conventional photonics technology. To increase the emission and detection efficiency, various antennas have been adopted. In this work, we provide experimental characterizations of various kinds of antenna-integrated photomixers by measuring ref...
Conference Paper
We have investigated the direct modulation characteristics of a phase-shifted 1.3-μm dual-mode laser diode. Stable dual-mode operation and high spectral purity are maintained under 2.5-Gbps direct modulation.
Conference Paper
We characterize InGaAs Schottky barrier diodes (SBDs) with a variation in the anode size. High-efficiency terahertz (THz) pulse detection of the InGaAs SBDs is performed in the cases of anode diameters of 2 μm and 3 μm. The uniformity of the fabricated 1 × 20 InGaAs SBD array is measured to be fine. The THz imaging results using the 1 × 20 InGaAs S...
Conference Paper
A travelling-wave photomixer was realized. The responsivity was 0.42A/W for 15μm length device. It showed a 3dB bandwidth of more than 200GHz, limited by transit-time of photo-generated carriers. Also, it showed a successful THz wave generation up to frequency range of more than 500GHz.
Article
We have developed a 1.3 μm phase-shifted dual-mode laser diode (pDML) for a tunable continuous-wave terahertz (CW THz) emitter. The mode beat frequency of the pDML is continuously tuned from 250 to 1480 GHz by introducing monolithically integrated micro-heaters and multiple sections to an all-active structure. The pDML shows a narrow spectral linew...
Conference Paper
We have developed a semiconductor optical amplifier integrated λ/4 phase-shifted 1.3-μm dual-mode laser as an optical beat source for continuous-wave (CW) terahertz (THz) generation. The CW THz system is also demonstrated with low-temperature-grown InGaAs photomixers.
Article
We demonstrate the tunable continuous-wave (CW) terahertz generator based on the λ/4 phase-shifted 1.3 μm dual-mode laser diode (DML) and travelling-wave photodiode (TWPD). The DML and TWPD operate as an optical beat source and terahertz photomixer, respectively. The laser diodes (LDs) operating at the 1.3 μm have more suitable characteristics as o...
Article
Full-text available
A simple thickness measurement method based on the coherent homodyne CW THz system was demonstrated; it does not require precise control of the frequencies of the beat source, and only accurate scanning of the optical delay line is needed. Three beat frequencies are sufficient for measuring the thickness of a sample without considering the modulo 2...
Conference Paper
We present a THz scattering-type scanning near-field optical microscope (THz s-SNOM) system. To estimate pure material resolution of our THz s-SNOM system, near-field images were obtained for embedded metallic grating. The pure material resolution of our THz s-SNOM system was estimated to be less than 100 nm.
Article
Full-text available
We present quantitative coherent measurements of scattering pulses and spectra in terahertz apertureless near-field microscopes. Broadband near-field image contrasts for both amplitude and phase spectra are measured directly from time-domain scattering signals with an unprecedentedly high single-scan signal-to-noise ratio (∼48 dB), with approach cu...
Article
Articular cartilage forms a thin layer and has a specialized molecular composition and structural organization along its depth, which consists of superficial, transitional, deep, and calcified zones. Terahertz (THz) pulse imaging is an emerging technique that was developed as a result of recent advances in THz technology. THz pulse imaging is a coh...
Article
Full-text available
We present the analysis and measurements of scattering signals of a terahertz pulse scattering-type near-field microscope. We used a self-consistent line dipole image method for the quantitative analysis of the THz near-field interaction. The line scan across a gold film demonstrated that the terahertz microscope has a nanoscale resolution of ~80 n...
Article
Full-text available
We demonstrated quantitative analysis and measurements of near-fields interactions in a terahertz pulse near-field microscope. We developed a self-consistent line dipole image method for the quantitative analysis of the near-field interaction in THz scattering-type scanning optical microscopes. The measurements of approach curves and relative contr...
Article
Full-text available
Lymph node metastasis is an important prognostic factor in cervical cancer patients. We report THz imaging for detecting micro-metastatic foci in the lymph nodes of early-stage uterine cervical cancer patients. Five paraffin-embedded metastatic lymph nodes from two cervical cancer patients were imaged using a THz time-domain spectroscopy system in...