• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.264-265
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• 2001

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.150-151
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.299-300
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• 2006

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.548-553
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• 2002

We have investigated the output characteristics of a Nd:YAG oscillator with a Stimulated Brillouin Scattering phase conjugation mirror (SBS-PCM). FC-75 is used as an SBS gain medium and Cr:YAG (T=50%) as a Q-switcher. The SBS-PCM consists of an SBS-cell and a simple plano-convex focusing lens system. For the case of not using a Q-switcher, an SBS-cell doesn't work as a phase conjugation mirror. For the case of using a Q-switcher, the energy characteristics remains nearly the same whether using the SBS-cell or not using it. The pulse width is reduced from 50 ns to 40 ns by an SBS-PCM. When the SBS-cell is used with a Q- switcher, the SBS-cell works very well as a phase conjugation mirror and its beam-profile is improved dramatically. And in order to explain the progression of beam-profile, we propose a simple model based on the nonlinear reflectivity of the SBS-PCM, whose reflectivity is dependent on the pumping intensity at the focal plane.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.167-173
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• 2019

In this paper, we studied characteristics of stimulated Brillouin scattering (SBS) suppression in high-power fiber lasers by using apparatuses applying a temperature gradient (i.e. a step, a sine shape, and random temperature distribution) along the fiber. From the ytterbium-doped polarization-maintaining fiber master oscillator power amplifier built in house, we measured the back-reflection spectrum and power for each temperature gradient, showing that the step shape temperature distribution was the most effective way to suppress SBS. In addition, we investigated the interaction of pseudo-random binary sequence phase modulation conditions and temperature gradients for SBS suppression.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.187-194
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• 2021

This paper presents a study of laser output characteristics. We fabricated a MOPA (master oscillator power amplifier)-type high-power, narrowbandwidth fiber laser with a bidirectional pumping configuration in its main amplifier. As signal beams, light sources with bandwidths of 3 GHz and 10 GHz-phase-modulated through a PRBS (pseudo-random binary sequence)-were used interchangeably. Furthermore, the characteristics of the SBS (stimulated Brillouin scattering) were analyzed using a signal beam with 3 GHz bandwidth, by adjusting the forward to backward pumppower ratio. Moreover, the characteristics of the transverse mode instability were analyzed by adjusting the forward to backward pump-power ratio, using a signal beam with 10-GHz bandwidth. Finally, the output power from 10 GHz bandwidth was amplified to more than 1 kW using a forward to backward pump-power ratio of 1.6. The beam quality M² was measured to be approximately 1.36, and the optical-to-optical efficiency was 80% at maximum output power.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.4
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• pp.272-277
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• 2013

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.1
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• pp.61-66
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• 2008

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.274-274
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 2005.02a
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• pp.39-39
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• 2005