• Bulletin of the Korean Chemical Society
• /
• v.25 no.1
• /
• pp.101-105
• /
• 2004

The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ~1,500 for the ytterbium.

• Journal of the Optical Society of Korea
• /
• v.13 no.4
• /
• pp.416-422
• /
• 2009

We have demonstrated a highly efficient cladding-pumped ytterbium-doped fiber laser, generating $>$2.1 kW of continuous-wave output power at 1.1 μm with 74% slope efficiency with respect to launched pump power. The beam quality factor ($M^2$) was better than 1.2. The maximum output power was only limited by available pump power, showing no evidence of roll-over even at the highest output power. We present data on how the beam quality depends on the fiber parameter, based on our current and past fiber laser developments. We also discuss the ultimate power-capability of our fiber in terms of thermal management, Raman nonlinear scattering, and material damage, and estimate it to 10 kW.

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 2006.06a
• /
• pp.108-111
• /
• 2006

Recently, mobile information devices, such as cellular phone, PDA(Personal Digital Assistant, PDA) are getting smaller and thinner. Accordingly, ultra precision welding technology is required to manufacture the high performance system for use in the telecommunication industry. In this study, we propose the laser micro welding process. Using ytterbium fiber laser, a wide range of experiments have been carried out for the gold wire-to-gold thin film welding.

• Journal of the Optical Society of Korea
• /
• v.17 no.2
• /
• pp.182-187
• /
• 2013

We present a comparative experimental analysis of the thermal spectroscopic characteristics of a phosphosilicate (P)-based ytterbium-doped fiber (YDF) against an aluminosilicate (Al)-based YDF in the temperature range of 25 to $150^{\circ}C$. We also characterize the fibers as gain media in a cladding-pumped amplifier configuration. While both fibers exhibit comparable trends in their thermal characteristics, there are noticeable distinctions in the fluorescence lifetime reduction rate and the spectral dependence of the transition cross-sections. The P- and Al-based YDFs present thermal lifetime reduction rates of $0.012%/^{\circ}C$ and $0.026%/^{\circ}C$, respectively. In particular, in the spectral region at ~940 nm, the absorption cross-section of the P-based YDF undergoes significantly less thermal change compared to that of the Al-YDF. In the cladding-pumped amplifier configuration operating at a total gain of 10 dB, the Al-based YDF generally performs betters than the P-based YDF in the temperature range of 25 to $75^{\circ}C$. However, it is highlighted that in the high temperature range of over $75^{\circ}C$, the latter shows a less gain reduction rate than the former, thereby yielding higher relative output power by 3.3% for a 1060-nm signal, for example.

• Korean Journal of Optics and Photonics
• /
• v.24 no.2
• /
• pp.58-63
• /
• 2013

A theoretical analysis of the impact of rise time of a Q-switch on the output pulse performance is carried out in an Ytterbium-doped actively Q-switched fiber laser. The finite difference time domain (FDTD) method is used to numerically simulate the Q-switched fiber laser. It is shown that stable Gaussian-like pulse shape can be generated when the Q-switch rise time is increased and pulse repetition rate is enlarged.

• Korean Journal of Optics and Photonics
• /
• v.31 no.5
• /
• pp.223-230
• /
• 2020

In this paper, we have studied the characteristics of stimulated Brillouin scattering (SBS) and mode instability (MI) in a ytterbium-doped polarization-maintaining fiber laser with master oscillator power amplifier configuration. We measured the laser output power and back-reflection spectrum for a variety of ytterbium-doped fibers and seed lights, to investigate the power-scaling limits of fiber lasers. By optimizing the laser structure, we demonstrated an all-fiber high-power polarization-maintaining fiber laser with near-diffraction-limited beam quality. The output power of 1.5 kW was achieved with a linewidth of 10 GHz, generated by pseudo-random binary sequence (PRBS) phase modulation. The beam quality M² was about 1.15 at the maximum output power. The polarization extinction ratio (PER) was greater than 17 dB.

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.02a
• /
• pp.183-184
• /
• 2007

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.07a
• /
• pp.89-90
• /
• 2007

• Proceedings of the Optical Society of Korea Conference
• /
• 2005.07a
• /
• pp.316-317
• /
• 2005

• Korean Journal of Optics and Photonics
• /
• v.32 no.4
• /
• pp.147-152
• /
• 2021

We report high-power continuous-wave operation of a Yb-doped fiber laser at 1070 nm, pumped by high-power laser diodes at 976 nm. Based on theoretical calculation of the stimulated Raman scattering and temperature distribution in the fiber, we construct a bidirectionally pumped Yb-fiberlaser system incorporating a pair of fiber Bragg gratings and a cladding light stripper. The fiber laser yields 3.0 kW of continuous-wave output at 1070 nm in a diffraction-limited beam with M² ≈ 1.26 for 4.1 kW of incident pump power, corresponding to a slope efficiency of 81.5%. The prospects for further power scaling are discussed.