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Photorefractive effect in a periodically poled Ti:LiNbO3 channel waveguides
Yeung Lak Lee,Changsoo Jung,Do-Kyeong Ko,Jongmin Lee,Young Chul Noh 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.2
The shift of the quasi-phase-matched wavelength and the degradation of the second harmonic power due to photorefractive damage (`optical damage') were investigated quantitatively as functions of the sample temperature and the coupled fundamental power in a Ti-diused periodically poled LiNbO3 channel waveguide. The all-optical wavelength conversion was successively demonstrated by using the cascaded dierence frequency generation process in a 76-mm Ti-diused periodically poled LiNbO3 channel waveguide at an operating temperature of 192 C. At that temperature, we observed no signicant degradation of the second harmonic power and a very small shift of the quasi-phase-matched wavelength. The wavelength conversion eciency was measured to be က8 dB, and the signal-to-noise ratio of the idler က35 dB.
최성철,이영락,노영철,이종민,고도경,이정훈,김강윤,김창종,이웅상,허명구,Choi, Sung-Chul,Lee, Yeung-Lak,Noh, Young-Chul,Lee, Jong-Min,Ko, Do-Kyeong,Lee, Jung-Hoon,Kim, Kang-Yoon,Kim, Chang-Jong,Lee, Ung-Sang,Heo, Myeong-Koo 한국광학회 2006 한국광학회지 Vol.17 No.2
펨토초 레이저 펄스를 이용하여 Slide glass 위에 코팅된 Al 박막표면에 나노패턴 구조를 생성하였다. 생성된 나노패턴 구조의 공간적 주기는 레이저 강도와 펄스 수에 의존함을 확인하였고, 레이저 강도와 펄스 수를 미세하게 조절함으로써 Al 샘플 표면에 균일한 나노패턴을 형성 시킬 수 있다. 이와 같은 현상은 레이저 입사빔과 샘플 표면에서 산란되는 빛의 광학적 간섭에서 야기 된다. 또한, Al 박막표면 위에 형성된 산화막이 짧은 주기의 나노패턴을 형성하는데 중요한 역할을 수행하는 것을 확인하였다. Femtosecond laser-induced nano-patterning of an Al surface coated on a slide glass is reported in this paper. It was found that the period of the laser-induced nano-patterning was much dependent on the incident laser power and pulse number. Through finely adjusting the laser power and pulse number, uniform nano-patterns could be formed on the Al surface. It is based on the interference of the incident laser beam with some form of a surface scatted electromagnetic wave. It was also found that an Al oxide layer played an important role in forming the nano-patterning on the Al surface.
Kang, Chul,Lee, Yeung Lak,Jung, Changsoo,Yoo, Hyung Keun,Kee, Chul-Sik The Optical Society 2010 Optics express Vol.18 No.20
<P>We investigated terahertz pulses from a rotating fan-out type poled lithium niobate (LiNbO(3)) pumped by femtosecond laser pulses. In particular, the rotating fan-out type poled sample produces an uncertain phase-matching wave vector perpendicular to input laser pulses. Such a wave vector allowed us to observe terahertz pulses normally unobservable from bulk or periodically poled LiNbO(3) at large rotation angles because of the terahertz wave critical angle of LiNbO(3). Further, we explained center frequency dependence on rotation angles by difference frequency generation process with the uncertain wave vector. We also discussed bandwidth dependence and terahertz pulse power regarding rotation angles.</P>
Nandam, Ashok,Jung, Minwan,Lee, Yeung Lak,Shin, Woojin IEEE 2016 IEEE photonics journal Vol.8 No.6
<P>We have proposed a reverse ridge strip waveguide and a slot waveguide structure for the dispersion compensation at 1550 nm wavelength. The resonance between strip-and slot-waveguide modes has been used to calculate the dispersion at the required wavelength. The effective indices of the proposed waveguide structure have been calculated by using the finite difference time-domain (FDTD) method. Our proposed structure shows a high negative dispersion of -1.46 x 10(5) ps/km-nm over a full width at half maximum (FWHM) of 14 nm at 1552-nm wavelength. The present structure should find applications in the design of integrated-optic dispersion compensators for optical telecommunication and ultrafast waveguide lasers.</P>
Yu, Nan-Ei,Lee, Yong-Hoon,Lee, Yeung-Lak,Jung, Chang-Soo,Ko, Do-Kyeong,Lee, Jong-Min Optical Society of Korea 2007 Current Optics and Photonics Vol.11 No.4
A high-conversion efficiency, nanosecond pulsed optical parametric generation and amplification with repetition rate of 20 kHz based on a periodically poled MgO-doped stoichiometric lithium tantalate was presented. Pumped by a Q-switched $Nd:YVO_4$ laser at 1064 nm with a pumping power of 4.8W, the generated output power was 1.6W for the signal and idler waves, achieving a slope efficiency of 50%. Using a seed source at signal wave the amplified signal output-pulse energy reached $65{\mu}J$. The obtained maximum gain was 72.4 dB.
Characteristics of Sŏlc Filters in X<sup>(2)</sup> Nonlinear Photonic Crystal
Kee, Chul-Sik,Lee, Jong-Min,Lee, Yeung-Lak Optical Society of Korea 2007 Current Optics and Photonics Vol.11 No.3
The characteristics of $S\breve{o}lc$ filters in $X^{(2)}$ nonlinear photonic crystals, periodically poled lithium niobate ($LiNbO_3$), were investigated by the Jones matrix method. The transmittance increases and the full width half maximum of the filter becomes narrow as the duty ratio increases. However, the filtering wavelength does not change. The transmittance at the filtering wavelength is over 95% when the duty ratio is larger than 0.35.