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The Lasing Characteristics of a Passively Q-Switched Nd:YVO4 Laser Using a Cr:YAG Saturable Absorber
Jonghoon Yi,Jin Hyuk Kwon 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
A diode-pumped, passively Q-switched Nd:YVO$_4$ laser was fabricated. A composite crystal, 0.6 \% Nd doped YVO$_4$ crystal block bonded with an undoped YVO$_4$ crystal cap, was used. The end cap reduced thermal lensing as well as thermal stress, when the crystal was end pumped by using a fiber coupled diode laser. Cr:YAG crystals with initial transmission of 80 \% or 90 \% were used as saturable absorbers. For each Cr:YAG crystal, several output couplers with different reflectivity were tested. The variations in the pulsewidth, the pulse repetition rate, and the average output power of the passively Q-switched laser were measured while varying the diode pump power for each value of the output coupler reflectivity and the Cr:YAG initial transmission. The dependences of the lasing characteristics on the output coupler reflectivity and the Cr:YAG initial transmission were explained.
Study on the isotope shift and hyperfine structure measurements in Gd I by violet diode laser
Jonghoon Yi,Hyunmin Park,Duck-hee Kwon 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.42
We investigated the isotope shifts and the hyperne structures of the gadolinium atom by using a violet diode laser. The spectra were obtained by using Doppler-free saturated absorption spectroscopy on atoms in a hollow cathode lamp. The atom in the ground state was excited to the 4f75d26p 11G1 state by using a single-mode violet diode laser. Also, the transition from the metastable (4f75d6s2 9D4) state to the 4f75d26p 11G4 state was investigated. From the spectra of the transitions, the hyperne structure constants of both excited states were estimated. For both transitions, the span of the isotope shift ranged about 6 GHz and isotope shift of 155Gd from the nearest isotope, 156Gd, was larger than 1.1 GHz. The spread of the hyperne structure was about 150 380 MHz. These results show that a diode laser can be used for selective excitation of the odd isotopes of Gd.
A Ti:Sapphire laser with a Frequency Selector Consisting of a Transmission Grating and Mirror
Jonghoon Yi 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.2
The lasing characteristics of a Ti:Sapphire laser with a frequency selector is measured. The selector consists of a transmission grating and a mirror. The laser was longitudinally pumped by a ashlamp pumped, Q-switched, frequency-doubled Nd:YAG laser. The rst-order diracted beam from a transmission grating with a 600-lines/mm groove density was send back to the gain medium by the full mirror. The lasing bandwidth of the pulsed Ti:Sapphire laser without the selector was 24.3 nm, which was reduced to 0.31 nm by using the selector. The wavelength was tuned by rotating the mirror. The conversion eciency and the temporal prole were calculated by using a set of rate equations. The calculated lasing characteristics as functions of the diraction loss in the grating described the experimental results well.
이용우,이종훈,김광석 嶺南大學校基礎科學硏究所 2001 基礎科學硏究 Vol.21 No.-
Diode pumped solid-state laser has very long lifetime and high efficiency compared with flashlamp pumped laser. We developed a highly efficient and miniature size green laser using an intra-cavity frequency doubling scheme. A Nd:YVO_4 crystal was end-pumped by a single diode with 808 ㎚ wavelength to generate infrared beam. When we used a KTP crystal for frequency doubling, we obtained green power more than 100 mW.
이용우,이종훈 嶺南大學校基礎科學硏究所 2002 基礎科學硏究 Vol.22 No.-
We tried to reduce laser power fluctuation due to beating between multi longitudinal modes. Single longitudinal mode lasing was achieved by using a simple etalon made by cover-glass and it dramatically reduced laser fluctuation from 49% to 10%.
Son, Phil Kook,Yi, Jonghoon,Kwon, Jin Hyuk,Gwag, Jin Seog Optical Society of America 2011 Applied optics Vol.50 No.10
<P>We present a single-cell gap-transflective liquid crystal display (LCD) characterized by a ? cell having bulk-type liquid crystal (LC) bistability and an optical film configuration. The ? cell has two stable states, which are a twisted and a nontwisted LC state. We used the twisted LC state for the reflective part connected with nonpatterned electrodes, producing a vertical field in the proposed transflective LCD. Also the nontwisted LC state was for the transmissive part with interdigitated patterned electrodes driving an in-plane field in the device. The simulated and experimental results show good electro-optical characteristics in both the reflective and transmissive parts.</P>
Development of a 10-TW, 27-fs Ti:sapphire Laser System at KAERI
Lee Yong Woo,Yi Jonghoon,Cha Yong Ho,Han Jae Min,Jeong Young Uk,Lee Byoung Chul,Nam Sung Mo,Rhee Yong Joo,Yoo Byung Duk 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.1
We have developed a 10-TW Ti:sapphire laser system for the study of laser-driven radiation sources at Korea Atomic Energy Research Institute. The laser system utilized only one pump laser (1.5-J energy at 532 nm) for the amplifiers and produced 27-fs, 300-mJ pulses at a 10-Hz repetition rate. The whole laser system composed of an oscillator, a pulse stretcher, three amplifiers, and a pulse compressor was installed on a 1.5 m × 3.0 m optical table with a separate vacuum chamber for the pulse compressor. A broad amplified spectrum supporting a 20-fs pulse duration was obtained at 10-TW level and was compared with simulated results.頂?
An Optically Pumped Colloidal Quantum Dot Laser Using a Hollow Fiber
Park, Soo-Min,Yi, Jonghoon,Ju, Young-Gu American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.10
<P>We fabricated a colloidal quantum dot (CQD) cavity by packing CQDs into a hollow fiber and attempted optical pumping with an Nd:YAG pulse laser. CQDs loaded into a hollow fiber forms a Fabry-Perot cavity along the fiber axis. Photoluminescence (PL) measurement showed that the emission peak was at 647 nm and the linewidth was 60 nm. When the CQD cavity was optically pumped by an Nd: YAG pulse laser, the linewidth shrunk to 5 nm with an emission peak at 649 nm. The laser output power was proportional to the input pump power, and the threshold pump irradiance was less than 500 kW/cm(2).</P>