• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.23-24
• /
• 2007

• Current Optics and Photonics
• /
• v.1 no.5
• /
• pp.525-528
• /
• 2017

High-energy, high-power, quasi-continuous wave (QCW) operation of double-clad Yb fiber lasers incorporating an incoherent signal combiner is reported. We constructed four efficient, high-power Yb fiber lasers, each of which produced rectangular pulses at 1080 nm with a pulse energy greater than 15 J, and a pulse duration of 10 ms at a repetition rate of 10 Hz, corresponding to an average power of over 150 W and a peak power of over 1.5 kW for ~200 W of incident pump power at 915 nm. These laser outputs were combined by a homemade incoherent fiber signal combiner with low loss, yielding a maximum peak power of ~6.0 kW in a beam with $M^2{\approx}12.5$. The detailed laser characteristics and prospects for further power scaling in QCW operation are discussed.

• Korean Journal of Optics and Photonics
• /
• v.4 no.1
• /
• pp.101-107
• /
• 1993

We carried out the useful theoretical calculation for the optimum design of a 1.48 ${\mu}m$ diode laser pumped E$r^{3+}$ doped fiber amplifier. The model we established is based on the rate equations of three level laser system and the overlap integral between fundamental mode L$P_{01}$ and E$r^{3+}$ doped area. We determined several fiber parameters (N.A., V value, fiber length, E$r^{3+}$ concentration, cutoff wavelength etc.) for the optimum design of a high optical gain. We found that our theoretical results are very useful to the design of E$r^{3+}$ doped fiber used in EDFA.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.468-470
• /
• 2005

본 연구에서는 NSOM(Near-field Scanning Optical Microscope)에서 정밀도의 중요한 요소로 작용하는 100 ~ 200nm Scale의 Optical aperture를 제작하기 위해 Optical Fiber를 이용하여 $CO_2$ Laser Heating Pulling Method에 의하여 제작하고자 한다. Heating Pulling Method 에서 Fiber Tip의 정밀도 및 제작 재현성에 영향을 미치는 중요한 기존의 여러 Fiber Tip 구현방법 중 본 연구에서는 Pulse Width[$PW_{(SEC)}$] 와 Pulling Force 두 요소에 있어서 상호관계를 연구하였으며, 연구 결과 두 변수간의 최적화된 파라미터인 PW 0.07 ~ $0.10_{(SEC)}$ 와 Pulling force 0.2 ~ 0.81b의 구간에서 error율이 최소화되는 범위를 찾을 수 있었고, 그 결과 최적의 상태는 $0.08_{(SEC)}$와 0.21b에서 팁들은 첨예화 되었고 95% 이상의 재현성 및 신뢰성을 얻을 수 있었다.

• Journal of Industrial Technology
• /
• v.28 no.B
• /
• pp.235-238
• /
• 2008

In this paper, we have developed wavelength swept laser system for the swept source optical coherence tomography(SS-OCT). A laser is constructed by using the two SOAs parallel configuration, fiber Fabry-Perot tunable filter(FFP-TF). The wavelength sweeps are repetitively generated with the repetition period of 50Hz. The wavelength tuning range of the laser is more than FWHM of 80nm centered at the wavelength of 1310nm and the line-width of the source is 0.12 nm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.727-728
• /
• 2013

• Proceedings of the Optical Society of Korea Conference
• /
• 1996.09a
• /
• pp.66-66
• /
• 1996

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.1
• /
• pp.33-41
• /
• 2011

To substitute TLS in the hybrid system which is combined with Sagnac interferometer and fiber bragg grating (FBG) it is necessary to investigate how the laser source (TLS and CW) and sensor material variate the response of fiber optic sensor. Two different hollow cylinder type mandrel materials are proposed which are PTFE and PTFE+carbon and 18 m optical fiber is wounded at the mandrel surface. CW laser source experiments had been done in the oil tank which is filled with transformer oil in the 1 kHz~20 kHz frequency range. Also Sagnac interferometer fiber optic sensor is combined with FBG called hybrid system and TLS used as a light source. Based on the experimental results PTFE sensor showed more higher magnitude of detection signal rather than carbon sensor and this result is agreement with the McMahon's theoretical results. Phase variation is inversely proportional to the elastic modulus of the mandrel material. In PTFE fiber sensor, tunable laser source showed more higher performance rather than CW case. Therefore, TLS fiber optic sensor can be applied to the hybrid system which is combined with Sagnac and FBG.

• The Journal of the Korean dental association
• /
• v.47 no.8
• /
• pp.479-486
• /
• 2009

Purpose: The aim of this study was to show the clinical results of combination of Nd-YAP (1340nm) laser therapy with conventional endodontic and periodontal treatment. Materials and Methods: Four patients with chronic advanced periodontitis and endodontic infection were treated with conventional treatment and Nd-YAP laser therapy. Occlusal adjustment and splinting were done for stabilization of the teeth with severe horizontal and vertical mobility. The protocol for periodontal treatment was followed as scaling and root planing, pocket irrigation with 3% $H_2O_2$ and exposure of Nd-YAP laser using 320${\mu}m$ optical fiber with 160mJ/pluse, 30Hz. The other protocol for endodontic treatment was followed as access opening, canal preparation by hand and rotary instrument, canal filling, and exposure of Nd-YAP laser using 200${\mu}m$ optical fiber with 200mJ/pluse, 10Hz and 180mJ/pluse, 5Hz which were used respectively for disinfection and canal filling. The assessments of probing depth, mobility, and radiography were made prior to and after treatment. Result: All of these four clinical cases showed good healing of periodontium, which presented decrease of mobility and pocket depth, and increase of bone regeneration and bone density on the radiography. Conclusion: The bactericidal effect of Nd-YAP laser would provide benefits for improving clinical results that are obtained from conventional therapy.

• Korean Journal of Optics and Photonics
• /
• v.21 no.6
• /
• pp.254-258
• /
• 2010

We investigate an optical technique for beam shaping and optical amplification of a pulsed laser diode without variation of its original properties, such as repetition rate and pulse duration. The horizontal and longitudinal sizes of the pulsed laser diode are 300 and $2{\mu}m$, respectively, and its output power is $1.1mW/cm^2$. The multimodal and elliptical pulse shape of the laser diode is converted to the single-modal and Gaussian pulse shape by using a lensed optical fiber. Since the single-modal lensed fiber coupling from the multimodal pulsed laser diode degrades the output power severely, the output power of the pulsed laser diode is dramatically enhanced by using an optical amplification method based on master oscillated power amplification (MOPA). The pulse qualities of the laser diode are not changed after amplifying the pulse power and the output power was finally measured to be $29mW/cm^2$.