• Journal of Communications and Networks
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• v.10 no.1
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• pp.1-4
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• 2008

This paper reports the design of a multiwavelength fiber laser source that utilizes a linear cavity of hybrid Brillouin/Erbium fiber laser (BEFL). The output power, threshold power and free running cavity modes were investigated against the pump powers. The structure exhibited low threshold operation of 4 mW at 2.3 mW injected Brillouin pump power. The optimization of Brillouin pump wavelength, power and Erbium gain led to a maximum possible number of channels generated. Simultaneous and stable operation of 21 channels with 10.88 GHz channels spacing were obtained from this architecture at 1 mW injected Brillouin pump power and 90 m W Erbium doped fiber pump power in the 1555 nm region.

• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.196-201
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• 2007

A theoretical study of Brillouin optical time domain analysis (BOTDA) using two pulse lasers is performed. Even though a point detection is made for a pump pulse period, the dynamic range of BOTDA using two pulse lasers is approximately 5 dB more than that of a pulse and a CW laser when the fiber length is 140 km and the Stokes power is 1 mW.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.337-341
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• 2004

In this paper the effect of chaos induced instability in Brillouin-active fiber-ring sensor is described. The inherent optical feedback by the backscattered Stokes wave in optical fiber leads to instabilities in the form of optical chaos. The paradigm of optical chaos in fiber serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in communication and sensing. At weak power, the nature of the Brillouin instability can occur at before threshold. At strong power, the temporal evolution above threshold is periodic and at higher intensity can become chaotic. The threshold for the Brillouin instability in fiber-ring sensor is much lower than the threshold of the normal Brillouin instability process.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.434-441
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• 1993

Focusing geometry dependence of output Stokes energy in single pass methane Raman shifter is investigated. The experimental result shows that the threshold energy decreases as confocal parameter increases. This result can be explained by gain suppression caused by Stokes - anti-Stokes coupling. In this paper, we give simple analysis for the focusing geometry dependence of Stokes - anti-Stokes coupling and present the criterion of confocal parameter to reduce the gain suppression. Focusing geometry dependence of stimulated Brillouin scattering is measured and the result is in good agreement with theoretical prediction.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.162-166
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• 2014

The impact of booster section length made from passive erbium-doped fiber (EDF) on the L-band multiwavelength Brillouin-Erbium fiber laser (MBEFL) is studied experimentally in this paper. The influence on the performance of MBEFL in term of number of generated Stokes lines, tuning range and lasing threshold were investigated. A comparison was made between MBEFL without a booster section and with booster sections of different lengths. Through comparative study and at fixed BP power and 100mW of 1480 pump power, longer passive EDF length of 5m exhibits the highest average number of Stokes lines of 23 with tuning range of 14nm. In contrast, shorter passive EDF length of 1m shows the highest tuning range of 17nm and an average number of 21 Stokes lines.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.37-44
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• 1994

The characteristics of stimulated Brillouin scattering wave for applications to high power laser was experimentally investigated. The peak power reflectivity and the phase conjugation fidelity of Stokes wave with respect to the focal length of lens were measured, and the phase conjugation fidelity for a compressed part of the Stokes wave was also investigated. For the long focal length of lens.(f=100 cm), the peak power of the Stokes wave amounts to about twice as high as that of incident wave. The phase conjugation fidelity for the compressed leading pulse is up to 90%, better than that for other temporal parts of the Stokes pulse. In spatial distribution, the Stokes pulse from the axial region has the largest SBS gain, and it has been ascertained as a best candidate to the application due to excellent pulse compression, peak power reflectivity, and good phase conjugation fidelity.

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.142-143
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• 2000

파장분할 다중화 방식(WDM)이 광통신 시스템의 통신 속도를 획기적으로 향상시키는 방법으로 자리잡음에 따라 다파장 발생에 관한 많은 연구가 이어지고 있다. 지금까지의 연구 결과들은 크게 두가지로 나눌 수 있는 데, 넓은 대역의 이득 매질에서 다양한 방식의 파장선택 특성들을 이용하여 여러 개의 파장을 원하는 간격으로 발생시키는 방법$^{(1).(2)}$ 과 하나의 외부레이저 신호입사에 의한 유도산란을 통하여 일정한 파장간격을 가진 연속차수의 스토크스 신호를 발생시키는 방법$^{(3).(4).(5)}$ 이 있다. (중략)

• 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.