• Analytical Science and Technology
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• v.7 no.1
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• pp.1-10
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• 1994

A survey was made on detection limit, reproducibility, matrix effect, linear dynamic range and the memory effect of yttrium and europium in order to analyze rare earth elements which exist as impurities in the rare earth oxide which is raw materials of fluorescent substance. When analysing a certain amount of thulium quantitatively using inductively coupled plasma mass spectrometry, it was found that the analysis was interfered with $EuO^+$ which is one of polyatomic ions caused by plasma. As the intensity of thulium linearly proportional to the europium concentration, it was possible to the determine the actual concentration of thulium.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.439-441
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• 2003

본 연구에서는 Thulium(Tm$^{3+}$ )이 첨가된 광섬유를 이용, Upconversion blue 레이저의 개발을 위해 fiber 길이 및 파워 변화에 따른 최적화된 설계 기준 값을 찾기 위한 시뮬레이션 코드를 개발하고 그 해석을 행하였다. 1140nm의 여기광원을 이용하여 여기하였을 때 광섬유 길이 40cm에서 약 100mW의 발진 문턱값을 갖으며 1W의 여기 광원에 대해 60mW의 출력 특성이 예상된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.349-352
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• 2001

The transient response in TDFA(Thulium-Doped Fiber Amplifier) is theoretically investigated. The TDFA has the spectral gain band in 1.47 ${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, the signal power and their transient variation along the fiber amplifier. The results of numerical analysis can predict the gain saturation and recovery time at the fiber amplifier. It also shows the gain saturation and recovery effect depending on the pumping and saturation rate.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.17-21
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• 2004

We demonstrate an S/S＋band discretely tunable thulium doped fiber laser (TTDFL), anchored on a 50-㎓ ITU-T grid. Investigating the inversion analysis of the thulium doped fiber (TDF) in applying a dual wavelength (1.4 m and 1.5 m) pumping scheme, a laser whose tuning range covers most of the S/S＋band has been obtained. Within the wide 3-㏈ bandwidth of 65.1 nm, the output power of the tunable laser exceeds 6.1 ㏈m with very flat spectral profile and the number of DWDM channels generated is as large as 178. If we increase the subsidiary pump power to 22 ㎽, the bandwidth is expanded up to 66.2 nm. By controlling the temperature of the fine grid filter, we have also shown that the frequency locking capability of the laser can be improved. The laser developed in this work is expected to be utilized as a practical optical source providing reference wavelengths in the S/S＋band.

• Current Optics and Photonics
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• v.3 no.1
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• pp.1-7
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• 2019

Optical stimulation provides a promising alternative to electrical stimulation to selectively modulate tissue. However, developing noninvasive techniques to directly stimulate excitable tissue without introducing genetic modifications and minimizing cellular stress remains an ongoing challenge. Infrared (IR) light has been used to achieve optical pacing for electrophysiological studies in embryonic quail and mammalian hearts. Here, we demonstrate optical stimulation and pacing of the embryonic chicken heart using a pulsed infrared thulium laser with a wavelength of 1927 nm. By recording stereomicroscope outputs and quantifying heart rates and movements through video processing, we found that heart rate increases instantly following irradiation with a large spot size and high radiant exposure. Targeting the atrium using a smaller spot size and lower radiant exposure achieved pacing, as the heart rate synchronized with the laser to 2 Hz. This study demonstrates the viability of using the 1927 nm thulium laser for cardiac stimulation and optical pacing, expanding the optical parameters and IR lasers that can be used to modulate cardiac dynamics.

• Current Optics and Photonics
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• v.5 no.3
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• pp.306-310
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• 2021

A 200-W continuous-wave thulium-doped all-fiber laser at 2050 nm was developed with a master oscillator power amplifier configuration. For the master oscillator, a single-mode thulium-doped fiber laser was built with fiber Bragg gratings. The operating power of the oscillator was 10.1 W at a pump power of 20.9 W, and the slope efficiency was measured to be 53.0%. All emitted wavelengths of the oscillator were located between 2049.2 nm and 2049.9 nm, and no other peaks in different wavelength ranges were observed. The maximum output power of the final amplified beam was 204.6 W at a pump power of 350.4 W. The slope efficiency of the amplifier was measured to be 58.4%.

• Korean Journal of Optics and Photonics
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• v.25 no.6
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• pp.340-345
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• 2014

We experimentally demonstrate the use of a gold-deposited side-polished fiber as a $2-{\mu}m$-band polarizing device to produce mode-locked pulses from a thulium/holmium-codoped fiber ring cavity. The mode-locking effect was induced by nonlinear transmission caused by the gold-deposited side-polished fiber, due to nonlinear polarization rotation of the oscillated beam within the fiberized cavity. It is also shown that ~558-fs pulses with a peak power of ~6.7 kW could readily be produced at a wavelength of 1935 nm through subsequent thulium/holmium-codoped fiber amplification, due to the higher-order soliton compression effect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.533-534
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• 2002

In this paper, we studied the transient gain response in TDFA(Thulium-Doped Fiber Amplifier) theoretically. We also investigated the limitation of the gain saturation and recovery time when the short pulse trains are incident into the TDFA with the spectral gain band in 1.47${\mu}{\textrm}{m}$ for using at WDM. We can predict the interval between the pulse train, pump power and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.

• Current Optics and Photonics
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• v.5 no.5
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• pp.544-553
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• 2021

A 40-W 200-ns 300-kHz thulium-doped fiber laser at 2050 nm with a master oscillator power amplifier configuration was developed, for application to lithium-isotope separation. The master oscillator generated a 5.35 W continuous-wave beam, which the pulse generator then broke into 200-ns pulses at 300 kHz. Then, the laser beam was amplified by passing through a two-stage amplifier. The output power finally obtained was 42.0 W at 2050 nm, and was stable for a long time, over 2 hours. In spite of this achievement, mode instability was observed in the output beam. This can be solved in the future by using a method such as tight coiling.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.679-681
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• 2007