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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.
Nonlinear Absortption processes in Triphenyamine-dithienothiophene-Triphyenylamine
Haeyoung Choi,Myoungsik Cha,han-Young Woo,Jong-Hyup Lee,kwanghee Lee,Kwang-sup Lee,Oh-Kil Kim 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
We investigated the nonlinear absorption mechanism in the triphenylamine-dithienothiophenetriphenylamine molecule by using laser pulses with two different pulse widths, 7 ns and 35 ps. The single-beam transmission measurement with a 7-ns pulse resulted in a larger nonlinear absorption than that with a 35-ps pulse and saturated at high input intensities due to the excited state absorption (ESA) initiated by two-photon absorption (TPA). For a quantitative characterization of the TPA and ESA contributions to the nonlinear absorption, we estimated the ESA spectrum and lifetime by using a pump-probe transmission measurement with a 35-ps pulse. A 5-level model was used to explain both the nonlinear absorption and the one-photon and the two-photon pumped fluorescence.
Real-time imaging by use of second-harmonic generation in a beta-barium borate crystal
Jaekwon Kim,Myoungsik Cha,Chang Won Kim,Gyerok Jeon,Hwan Hong Lim,Jung Hoon Ro,Oc-Yeub Jeon 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.6
Non-collinear second-harmonic generation (SHG) was performed using a beta-barium-borate crystal, aiming at real-time imaging through a scattering medium. In the present experiment, we successfully obtained a high resolution real-time image of the second-harmonic beam. Detailed analyses are given for the thickness of the nonlinear crystal and our resolution of the SHG imaging system.
third harmonic generation in organic octupole molecule with small absorption at 3ω
Park Jae hyun,Cha Myoungsik,Bong Rae Cho,Mi-Yun Jeong 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.2
The nonlinear optical properties of 1,3,5-tricyano-2,4,6-tri (p-diethylaminostyryl) benzene (TTB) thin lms have been measured by using third-harmonic generation (THG) at the fundamental wavelength of 1064 nm. By comparing the THG intensity with that of fused silica, we estimated the third-order electrical susceptibility of the organic lm to be 1.2 1011 esu, which is about 400 times larger than that of fused silica glass. Due to the unique properties of the TTB lms, such as anomalous dispersion and small re-absorption of the third harmonic wave, a thick lm is expected to give a more ecient THG, which can be applied to ultrafast optical correlators.
Min-Ji Jin,Myoungsik Cha,Byeong-Joo Kim,Oc-Yeub Jeon 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.2
Periodically poled lithium niobate (PPLN) is the most widely used crystal for practical implementation of quasi-phase matching (QPM). We periodically poled LiNbO3 single crystals by using an electric-field poling method. A series of PPLN samples with varying duty cycle was fabricated, and one of the faces was etched out to reveal a surface relief pattern. We measured the far-field pattern diffracted from the surface grating, and successfully evaluated the quality of the QPM grating, such as period stability and duty cycle. We could establish a quantitative relation between duty cycle information obtained from the diffraction measurement and the charge provided during the poling stage.
Choi, Hee Joo,Cha, Myoungsik The Optical Society 2014 Applied Optics Vol.53 No.24
<P>We developed an efficient method for measuring the principal refractive indices and thickness of an optically anisotropic wafer that involves the analysis of Fabry-Perot interference fringes. Utilizing the birefringence of the medium, the 2π phase ambiguity was readily resolved in single-wavelength measurements of the birefringent medium index. Although the accuracy of the index measurements is limited due to the innate ambiguity, our analysis method overcame this limit and could determine the principal refractive indices and thickness with an uncertainty of 10(-5). Our method was validated against measurements of a lithium niobate wafer for which the values of the indices are precisely known.</P>
Tunable all-optical wavelength broadcasting in a PPLN with multiple QPM peaks.
Ahlawat, Meenu,Tehranchi, Amirhossein,Pandiyan, Krishnamoorthy,Cha, Myoungsik,Kashyap, Raman Optical Society of America 2012 Optics express Vol.20 No.24
<P>We experimentally demonstrate tunable multiple-idler wavelength broadcasting of a signal to selective channels for wavelength division multiplexing (WDM). This is based on cascaded χ(2) nonlinear mixing process in a novel multiple-QPM 10-mm-long periodically poled LiNbO3 having an aperiodic domain in the center. The idlers' spacing is varied utilizing detuning of the pump wavelength within the SHG bandwidth. The temperature-assisted tuning of QPM pump wavelengths allows shifting the idlers together to different set of WDM channels. Our experimental results indicate that an overall idler wavelength shift of less than 10 nm realized by selecting pump wavelengths via temperature tuning, is sufficient to cover up to 40 WDM channels for multiple idlers broadcasting.</P>
Measurement of refractive index dispersion of a fused silica plate using Fabry-Perot interference
Lee, Choonghwan,Choi, Heejoo,Jin, Jonghan,Cha, Myoungsik The Optical Society 2016 Applied Optics Vol.55 No.23
<P>We used Fabry-Perot interferometry to measure the refractive indices of a fused silica plate at four different wavelengths ranging from 544 to 1550 nm, giving a detailed analysis on the uncertainty of this experimental method. Because of a small expanded uncertainty of 2.7 x 10(-5) (k = 1.96) obtained using the experimental method, it was possible to make corrections to the existing Sellmeier formula [J. Opt. Soc. Am. 55, 1205 (1965)] for our fused silica sample. The corrected Sellmeier formula resulted in a group index value larger than that evaluated using the Malitson's Sellmeier formula by 3 x 10(-4). We verified this by comparing it with the group index measured with spectral domain interferometry at 1530 nm. (C) 2016 Optical Society of America</P>
Measurement of thickness profiles of glass plates by analyzing Haidinger fringes
Park, Ju Eun,Kim, Jiung,Cha, Myoungsik The Optical Society 2017 Applied optics Vol.56 No.7
<P>We report what we believe is a novel method for measuring the thickness profiles of plane parallel plates by analyzing their Haidinger fringes. When an extended monochromatic source is viewed through a similar to 1-mm-thick plate, concentric transmission-type Haidinger fringes can easily be observed. Small variations in the plate thickness result in changes in the radii of the ring fringes. In this study, we scanned 20-mm-diameter fused silica and BK7 plates while tracing a specific ring in each fringe pattern to measure the thickness profiles of the plates, achieving an uncertainty of 2 nm in the measurements of the thickness differences between two locations on each plate. (C) 2017 Optical Society of America</P>