• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.60-65
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• 1996

Degradation of the optical communication system due to the stimulated Brillouin scattering effect in the optical fiber is measured, and its suppression is demonstrated. In the externally modulated 2.5 Gb/s transmission experiment, bit error rate is increased due to the stimulated Brillouin scattering effect when the signal power (linewidth 3 MHz) incident into the dispersion shifted fiber is larger than 10 dBm. SBS effect is suppressed completely, up to 15 dBm of transmission power, by broadening the source linewidth to 200 MHz.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.485-489
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• 2005

I have investigated a scheme for suppressing stimulated Brillouin scattering in optical fibers. The scheme makes use of a sampled Bragg grating fabricated within the fiber used for transmitting intense Q-switched pulses. The grating is designed such that the spectrum of the Stokes pulse generated through stimulated Brillouin scattering falls entirely within its stop band. I show numerically that the number of sampled fiber Bragg gratings in 1 m is applied directly to suppressing stimulated Brillouin scattering rather than the coupling coefficient. This prevents the build up of the backward-propagating Stokes wave and mitigates the deleterious effects of stimulated Brillouin scattering. The simulation shows that 15 ns pulses with 1 kW peak power can be transmitted though a 1 m-long fiber with little energy loss using this scheme.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.338-342
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• 2003

We have studied the properties of stimulated Brillouin scattering (SBS) in an optical fiber using optical pulses and continuous wave light. We find that the thresholds for SBS are the same when the averaged power of pulse light is the same as the power of cw light. From this result, the SBS threshold of pulse light can be deduced from that of continuous wave light, which can be obtained easily and accurately.

• Current Optics and Photonics
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• v.7 no.6
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• pp.665-672
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• 2023

This study focuses on investigating the impact of the spectral linewidth of a seed laser in a master-oscillator power amplifier (MOPA) configuration on stimulated Brillouin scattering and the beam quality of the output diffracted by a grating. To conduct the study, a distributed feedback (DFB) laser is modulated in a pseudorandom binary sequence (PRBS) and amplified by a two-stage Yb-doped fiber amplifier to achieve an output power of over 1 kW. The spectral linewidth of the seed laser is systematically varied from 1 to 12 GHz in the frequency domain by varying the PRBS modulation parameters. The experimental results reveal a tradeoff between suppressing stimulated Brillouin scattering and enhancing beam quality with increased spectral linewidth. Therefore, the study provides valuable insights into optimizing spectral beam combining to achieve high beam quality and scalable power upgrade in fiber lasers.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.324-330
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• 1995

Stimulated Brillouin scattering theory is described in an optical fiber. Frequency change with an optical heterodyne method is analyzed between reference signal of a source and stimulated Brillouin scattering signal in an optical fiber. By coupling a source with a few axial modes and an optical fiber ring resonator, Brillouin scattering is studied with a spectrum analyzer. Using reference beating signal of a source, we have reduced the Brillouin beating frequency from 13 GHz range to below GHz. Experimentally, we can see the Brillouin beating frequency from 13 GHz range to below GHz with a dispersion shifted fiber (1.32 GHz), Ti-doped fiber (900 MHz) and single mode optical fiber (870 MHz). MHz).

• Current Optics and Photonics
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• v.7 no.4
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• pp.378-386
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• 2023

A wideband instantaneous frequency measurement (IFM) system is been proposed, designed and analyzed. Phase modulation to intensity modulation conversion is implemented based on the stimulated Brillouin scattering (SBS) effect, and the microwave frequency can be measured by detecting the change in output power. Theoretical analysis shows that the frequency measurement range can be extended to 4f_b by adjusting the two sweeping signals of the phase modulators with a difference of 2f_b. The IFM system is set up using VPI transmission maker software and the performances are simulated and analyzed. The simulation results show that the measurement range is 0.5-45.96 GHz with a maximum measurement error of less than 9.9 MHz. The proposed IFM system has a wider measurement range than the existing SBS-based IFM system.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.232-233
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• 2002

비선형 광학 현상들 중 하나인 유도 브릴루앙 산란(Stimulated Brillouin Scattering; SBS)은 고체, 액체, 기체, 그리고 플라즈마 상태에서 광범위하게 관찰된다. 특히, 1990년대에 들어서면서 광섬유에서 나타나는 SBS가 주목을 받기 시작하면서 많은 연구가 이루어졌다(1-4). SBS 현상은 빔이 입사되는 방향의 반대방향일 때 가장 크게 일어나는데 일단 입사되는 빔의 출력이 SBS가 일어나기 위한 문턱 값을 넘을 때 지수적으로 증가한다(5). (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.335-336
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• 2008

We observe the distortion of the back scattered Stokes pulse and the complementary distortion of the transmitted pulse by the stimulated Brillouin scattering when a Q-switched Nd:YAG laser pulse injected into a single mode optical fiber. We determine the constant required energy for the SBS by comparing their temporal shapes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.92-97
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• 2008

This is a research to apply 1310nm single-mode optical fiber to a temperature sensor. The existing study of optical fiber sensor is complicated because it was made with various equipment. To vary scattering, the variation of optical frequency is measured by using Bragg(lattice) or pulse generator and also bulk system is created by YAG laser but there were some difficulties creating experimental environment and it was a problem that the stability of measured data was low. The temperature sensor system using the suggested sBs(stimulated Brillouin scattering:sBs) from this research is much more simplified straight-line system. To improve the trust and accuracy of noises from optical frequency and unclear results, it was analysed by using Neuro-Fuzzy algorithm. we tried to get more correct data than existing system. sBs measure that optical frequency changed due to the variation of temperature. The analyzed change rate of outcome by Fuzzy theory is 1.1 MHz.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.13-16
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• 2000

Since stimulated Brillouin scattering (SBS) impact wavelength division multiplexing (WDM) optical transmission systems, it is important to understand the implication of SBS in the design of such lightwave systems. Therefore, Brillouin gain spectrum (BGS) is measured to characterize the effect of SBS in optical fiber. The Brillouin gain coefficient is found to vary as the wavelength and linewidth of source. Theoretically measurement of BGS shows a dependence on wavelength(λ) and on linewidth(Δν), respectively.