http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
백인형,강봉주,정영욱,Fabian Rotermund 한국광학회 2014 Current Optics and Photonics Vol.18 No.1
We report the generation of 3.3-mW single-cycle terahertz (THz) pulses at 1-kHz repetition rate via optical rectification in MgO-doped prism-cut stoichiometric LiNbO3. Efficient pulse-front tilting of 800-nm pulses was realized by an optimized single-lens focusing scheme for radially-symmetric propagation of THz beams. In this geometry, nearly-diffraction-limited THz Gaussian beams with electric field strength as high as 350 kV/cm were generated. The pump-to-THz energy conversion efficiency of 1.36 × 10 -3 and the extremely high signal-to-noise ratio of ~1:15000 achieved are among the best results for 1-kHz singlecycle terahertz pulse generation ever demonstrated in room temperature operation.
강봉주,백인형,정재혁,김지수,이승헌,권오필,이상민 한국물리학회 2014 Current Applied Physics Vol.14 No.3
We investigated efficient terahertz wave generation by optical rectification in as-grown nonlinear organic single crystal HMQ-T (2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 4-methylbenzene sulfonate). Optimal thickness of crystals directly available by a slow cooling method in methanol solution enabled us to achieve high-field few-cycle THz waves at 800-nm pumping. With 95-mW pumping at 1-kHz repetition rate, an optical-to-THz conversion efficiency of 2.7 104 was achieved and the THz electric field strength, measured by electro-optic sampling, was as high as 110.1 kV/cm. Such an efficient THz source based on as-grown HMQ-T crystals can be used for investigation of various nonlinear phenomena in the THz spectral region.
김현우,장규하,백인형,이기태,정영욱,남진희,채문식,김미혜,김영찬,왕기영,박선정,한장희,Nikolay A. Vinokurov 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.1
We have developed a one-and-half -cell S-band radio-frequency (RF) photoelectron gun (pho- togun) fed by a coaxial coupler. The RF photogun is dedicated to ultrafast-electron-diraction experiments by generating electron bunches of 3-MeV energy and a-few-pC charge, which is not strict condition compared to those for X-ray free-electron lasers. Brazing of RF cavities is well- developed process for making RF guns or RF accelerators. Sometimes, however, a failure occurs in the brazing process, causing the entire electron gun or accelerating cavity to spoil. Axial-symmetric design of the RF photogun permits indium sealing for cavity cells, a photocathode plate, and a coupling RF part. We rstly report that the indium-sealed RF photogun successfully meets the required performance and long-term stability for ultrafast electron diraction experiments. We have stably operated the RF photogun for more than three years with the electron beam conditions of 3-MeV energy, up-to-10-pC charge, and a repetition rate of 50 Hz. The quantum eciency of the copper photocathode had improved from 106 to 105 depending on vacuum condition from 108 to 5 1010 Torr, respectively. Measured emittance and energy spread of the generated electron beam showed 0.3 mm-mrad and less than 0.25%, respectively, for a bunch charge of 2 pC, which agree well with those obtained by ASTRA simulation.