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Analysis on Transition between Index- and Bandgap-guided Modes in Photonic Crystal Fiber
홍기석,임선도,박희수,김승관 한국광학회 2016 Current Optics and Photonics Vol.20 No.6
We calculate optical properties of guided modes of a hybrid-guiding photonic crystal fiber. The designand modeling of such hybrid-guiding PCF is made by replacing air holes with inserts of high refractiveindex material layer by layer in order. The optical properties such as mode intensity profile, modedispersion, optical birefringence, confinement loss, and chromatic dispersion during transition of the guidingmechanism are analyzed and discussed. The guided modes in the hybrid-guiding region are also comparedwith those of reference index-guiding and bandgap-guiding photonic crystal fibers.
배인호,임선도,유재근,이동훈,김승관 한국광학회 2019 Current Optics and Photonics Vol.3 No.1
We report development of a frequency-stabilized mid-infrared continuous-wave (cw) optical parametric oscillator (OPO) based on a fan-out grating MgO:PPLN crystal pumped at 1064 nm. The OPO resonator was designed as a pump-enhanced standing-wave cavity that resonates to the pump and signal beams. To realize stable operation of the OPO, we applied a modified Pound-Drever-Hall technique, which is a well-known method for powerful laser frequency stabilization. Tuning a poling period of the fan-out grating of the crystal allows wavelength-tunable OPO outputs from 1510 nm to 1852 nm and from 2500 nm to 3600 nm for signal and idler beams, respectively. At the idler wavelengths of 2500 nm, 3000 nm and 3500 nm, we achieved more than 50 mW of output powers at a pumping power of 1.1 W. The long-term stability of the OPO was confirmed by recording the power and wavelength variations of the idler for an hour.
배인호,유재근,임선도,김승관,이동훈 한국광학회 2019 Current Optics and Photonics Vol.3 No.6
We report on a continuous-wave (cw) optical parametric oscillator (OPO) optimized for mid-infrared emission above 5.0 µm. The OPO is based on a magnesium-oxide-doped periodically poled LiNbO 3(MgO:PPLN) crystal with a fan-out grating design. A linear two-mirror cavity resonating both at the pump and signal wavelengths is stabilized to the pump laser by using the modified Pound-Drever-Hall (PDH) method. The idler wavelength is continuously tunable from 4.7 µm up to 5.3 µm by varying the poling period of the fan-out grating crystal. Pumped by a diode-pumped solid state (DPSS) laser with a power of 1.1 W at 1064 nm, the maximum idler output power is measured to be 5.3 mW at 4.8 µm. The output power above 5.0 µm is reduced to the hundreds of µW level due to increased absorption in the crystal, but is stable and strong enough to be measured with a conventional detector.
Fabrication of High-purity Rb Vapor Cell for Electric Field Sensing
유재근,이덕영,임신혁,홍현규,임선도,김승관,홍영표,강노원,배인호 한국광학회 2023 Current Optics and Photonics Vol.7 No.2
In this paper, we introduce our system for manufacturing a Rb vapor cell and describe its fabrication process in a sequence of removing impurities, cold trapping, and sealing off. Saturated absorption spectroscopy was performed to verify the quality of our cell by comparing it to that of a commercial one. By using the lab-fabricated Rb vapor cell, we observed electromagnetically induced transparency in a ladder-type system corresponding to the 5S 1/2 -5P 3/2 -28D 5/2 transition of the 85 Rb atom. A highly excited Rydberg atomic system was prepared using two counter-propagating external cavity diode lasers with wavelengths of 780 nm and 480 nm. We also observed the Autler-Townes splitting signal while a radiofrequency source around 100 GHz incidents into the Rydberg atomic medium.
Evaluation of Co-C, Ni-C, Re-C and δ(MoC)-C Fixed Points Fabricated at KRISS
Abdallah Mohamad Karmalawi,Saber Gomaa Rabie Salim,Yong Shim Yoo,Mohamed Amin Soliman,Bong Hak Kim,임선도 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.4
This paper presents the recent work that has been carried out at the Korea Research Institute of Standards and Science (KRISS) to fabricate and evaluate high temperature eutectic/peritectic fixed points: Co-C, Ni-C, Re-C and δ(MoC)-C fixed points. The research has been conducted as part of an internal research project that aims at fabricating high quality eutectic fixed points and measuring their thermodynamic temperatures with the lowest possible uncertainty. The fabrication procedures and instruments used for fabrication and investigation are described in details. ITS-90 temperatures for the four fixed points measured are presented with a melting range, repeatability, and expanded uncertainty. The Co-C and the Re-C fixed points are compared with those made at All- Russian Research Institute of Optical and Physical Measurements Federal State Unitary Enterprise (VNIIOFI) to validate our works. The results are also presented.