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Measurement of the Birefringence in Bulk Optical Media by Using Interferometric Methods
차명식,최희주,임환홍,김병주 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
Accurate knowledge of the index of refraction of an optical medium is of fundamental impor- tance in various optical applications. We applied a Michelson interferometer and Fabry-Perot-type interference methods to a wafer sample to estimate the difference between two orthogonal indices, Δn, of a LiNbO3 crystal wafer and we compared the results of the two methods. By measuring the transmittance with sample rotation, we obtained a beat pattern between the fringes of the ordinary and the extraordinary light waves. Fitting the node locations, we could determine the Δn value with an uncertainty of 10-3 with both methods. Since the Fabry-Perot method is insensitive to atmospheric turbulence and vibration and is very simple to implement, it alow a quick estimate of the birefringence in optical crystals.
Group Velocity Matched Second Harmonic Generation in Periodically Poled Potassium Niobate
차명식,유난이,Sunao Kurimura,Kenji Kitamura,Satoshi Ashihara,Takayuki Ohta,Tsutomu Shimura,Kazuo Kuroda,Oc-Teob Jeon 부산대학교 유전체물성연구소 2004 유전체 논문집 Vol.3 No.
We investigated the group velocity matched second harmonic generarion in periodically poled potassium niobate. The QPM wavelength bandwidth was 38 nm around 1520 nm at 35℃ in 14.4㎛ QPM period with 10.5 mm interaction length. We also observed ultra-fast pulse used type-ⅠSHG conversion efficiency. The SHG conversion efficiency of the PPKN crystal was about 3 times that of type-Ⅰ SHG in PPMgLN.
π-중심을 가진 유기 색소 분자의 비선형 흡수 과정 연구
최혜영,차명식,양현관,이광섭,이광희 한국물리학회 2004 새물리 Vol.48 No.1
We investigated nonlinear absorption processes in organic chromophores with thiophene and uorene À-centers. Laser pulses with durations of 7 ns and 35 ps were used to measure and compare the nonlinear absorption processes. Based on a ve level model for the molecules, we observed a much larger nonlinear absorption for the 7 ns pulse, which could be interpreted as being due to a two-photon absorption followed by an excited state absorption, We verifed that the strength of the nonlinear absorption increased not only with the two-photon absorption coecient but also with the lifetime of the excited state.
전옥엽,차명식,김병주,진민지 한국물리학회 2004 새물리 Vol.48 No.6
We investigated the optical properties of LiNbO3 crystal after annealed proton exchange with benzoic acid and high temperature water vapor. Especially, to qualify the eect of the proton exchange, we observed the OH vibration absorption peak at 2800 ~ 3000 nm, was observed. The change in the refractive index dispersion was also monitored by examining the phase-matched wavelength of type-I second harmonic generation.
전옥엽,차명식,김병주,Hwan-Hong Lim,Min-Ji Jin 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
We demonstrate broadband optical parametric generation in the telecommunication band and the associated simultaneous RGB generation by quasi-phase-matched parametric conversion processes in a periodically poled lithium niobate crystal pumped by picosecond pulses.
여러 회절광의 세기를 비슷하게 분배하는 회절격자의 제작
홍동리,차명식 한국물리학회 2007 새물리 Vol.54 No.3
A balanced or equal beam splitter is necessary in several optical experiments, such as complicated multi-beam pump-probe spectroscopy. We fabricated photoresist surface-relief gratings with different duty cycles in order to achieve relatively balanced intensities among the diffraction orders. A grating with a duty cycle of 1:3 gave relatively balanced beam splitting among the $\pm$0, $\pm$1, and $\pm$2 orders without significantly sacrificing the total diffraction efficiency. 한 개의 빔을 여러 개의 균일한 빔으로 나누는 beam 분배기는 복잡한 multi-beam pump-probe 분광학 실험 등의 광학 실험에 필요하다. 우리는 회절 차수들의 세기가 상대적으로 균일하게 나오게 하기 위해서 각각 다른 duty비로 photoresist 표면 위상 회절격자를 만들었다. Duty비 1:3의 회절격자는 전체 회절효율에 있어서 큰 손실 없이 $\pm$0, $\pm$1, $\pm$2차 회절광들의 세기를 비교적 균일하게 분배했다.