• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.507-511
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• 1999

A 10 GHz timing extracted signal which is phase-locked to a 10 Gbit/s mode-locked optical fiber laser pulse train is obtained using a tour-wave-mixing signal in semiconductor optical amplifier. The phase-locked loop wm, demonstrated ~Llccessful1y over 8 hours and found to have the lock-in frequency range of 30 KHz. 0 KHz.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.156-162
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• 2004

The spectroscopic model is proposed to analyze the gain bandwidth of a fiber Raman amplifier (FRA) with a multiple wavelength pumping scheme based on Raman gain theory. The oscillatory lineshape, which is the analytic function to analyze Raman gain spectra, allows us to estimate the gain bandwidth of the FRA. Based on the proposed theoretical modeling, we design and analyze the characteristics of the FRA using the combined multiwavelength pumping sources. We achieved the extended gain bandwidth of the FRA over 80 nm with the small gain ripple less than 0.5 dB. Threshold pumping power and effective noise figure for the FRA can be also analyzed by using the proposed model, which is also applicable for versatile fibers with other doping materials. The proposed analysis method can be useful for the design of FRA with the multiwavelength pumping scheme.

• Current Optics and Photonics
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• v.3 no.2
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• pp.105-110
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• 2019

The visible-light communication (VLC) system is a promising candidate to fulfill the present and future demands for a high-speed, cost-effective, and larger-bandwidth communication system. VLC modulates the visible-light signals from solid-state LEDs to transmit data between transmitter and receiver, but the broadcasting and the line-of-sight propagation nature of visible-light signals make VLC a communication system with a limited operating range. We present a novel architecture to increase the operating range of VLC. In our proposed architecture, we guide the visible-light signals through the fiber and amplify the dissipated signals using visible-light fiber amplifiers (VLFAs), which are the most important and the novel devices needed for the proposed architecture of the VLC. Therefore, we design, analyze, and apply a VLFA to VLC, to overcome the inherent drawbacks of VLC. Numerical results show that under given constant conditions, the VLFA can amplify the signal up to 35.0 dB. We have analyzed the effects of fiber length, active ion concentration, pump power, and input signal power on the gain and the noise figure (NF).

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.33-38
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• 2007

In this study, one-dimensional fiber-optic radiation sensor with an organic scintillator tip is fabricated to measure high energy X-ray beam profile of CLINAC. According to the energy and field size of X-ray, scintillating light signal from one-dimensional fiber-optic sensor is measured using a photodiode-amplifier system. This sensor has many advantages such as high resolution, real-time measurement and ease calibration over conventional ion chamber and film.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.1-9
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• 2005

We have studied the dispersion properties of a 40 channel x 10 Gbit/s wavelength division multiplexer(WDM) transmission link using standard single mode fiber with all EDFA amplification over 30 x 100 km spans. The dispersion map of the link was investigated by adding fiber sections with positive or negative dispersion at the transmitter, within each amplifier span, and at the receiver. Optimum combinations of these dispersive fiber lengths were attained to significantly enhance the overall transmission performance.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.396-400
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• 2006

We present a weather-insensitive optical free-space communication method supporting optical packet channels. It operates optical fiber amplifiers in gain-saturation regions. When the propagation loss gets too high, it decreases the average packet rate, or the average packet length, or both, to increase the optical power level launched into the free-space. As a demonstration, we transmit $8{\times}10$ Gigabit Ethernet channels over a terrestrial distance of 2.4 km. One gain-saturated free-space optical repeater is used at the halfway point.

• Journal of the Optical Society of Korea
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• v.11 no.4
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• pp.158-161
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• 2007

We proposed a novel linearization technique for a DFB LD in the RoF link. The proposed scheme is based on the cross gain modulation(XGM) effect of a reflective semiconductor optical amplifier(RSOA) with light injection. We experimentally demonstrated and evaluated the enhanced CIR performance using the proposed linearization scheme.

• Journal of the Optical Society of Korea
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• v.11 no.1
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• pp.44-48
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• 2007

A two-stage gain-clamped erbium doped fiber amplifier (GC-EDFA) using a pump laser diode and a 16 channel wavelength division multiplexing (WDM) with 0.8 nm spacing in C band of $1,545{\sim}1,560nm$ wavelength is experimentally demonstrated for a burst packet mode optical switching system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1203-1208
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• 2001

1545∼1560nm 파장의 C 대역에서 0.8nm 간격의 16 채널 WDM을 갖는 펌프 LD 타입의 2단 이득 제어 어븀 첨가 광섬유증폭기(GC-EDFA)를 버스트 패킷 모드 광스위칭 시스템에 사용하기 위하여 실험을 통해 입증하였다.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.140-142
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• 1989

1.54um 파장에서 최대 형광을 나타내는 ZrF4-BaF2-LaF3-AlF3-NaF : ErF3 유리를 built-in-casting 법에 의해 제조하였다. Er+3 이온을 0.2몰부터 4몰까지 첨가하였으며, Er+3 이온의 4I13/2 준위의 lifetime 은 Er+3 이온 0.2몰부터 2몰까지 28msec로 최대값을 갖으며 4몰일때는 급격히 감소하였다.