• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.291-297
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• 1994

A feedback loop with bandpass filter is introduced in erbium-doped fiber amplifier to clamp the amplifier gain by lasing the amplifier at a selected wavelength. The gain and the ASE (amplified spontaneous emission) output spectra are found to be independent of input signal power and pump power variation so long as the amplifier is lasing. Also they are found to be dependent only on the overall loss of the feedback loop. Even in the case of slowly modulated large signal input, signal distortion due to gain saturation is not observed.served.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.105-111
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• 2000

To realize a desired characteristics of an optical transversal fitters, The number of optical amplifiers as same as the lentgh of a given transfer function is needed In this paper, we consider an optical transversal filter that uses only one fiber amplifier, which can realize a constant(=$\alpha$) times of a given transfer function with e as large as possible in order to make use of optical signal energy. We also present some applications using this optical fiber filter.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.144-145
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• 2000

파장 분할 다중화(WDM)기술은 빠른 속도로 발전해 왔으며, 이에 대한 연구는 계속되고 있다. 전송용량의 증가에 의해 전송 채널의 수가 증가하고 이에 따라 이득 대역도 더 넓어져야한다.$^{(1)}$ 파장 분할 다중화(WDM) 시스템의 구성에서 어븀 첨가 광섬유 증폭기(EDFA)는 시스템의 핵심 요소로 각 단계마다 몇 개씩의 EDFA가 사용된다. EDFA에서는 이득의 변화가 10 ms정도로 천천히 일어나므로 입력의 평균값에 의해 이득이 결정된다. 따라서, EDFA는 모든 채널의 입력의 합이 일정할 때 이득의 상호 포화로 인한 채널 간의 누화가 없다는 장점이 있기 때문에 다채널 WDM 시스템의 광섬유 증폭기로 매우 유용하게 이용되고 있다.$^{(2)}$ (중략)

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.139-145
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• 2010

A complete modeling of erbium-doped Bismuth-oxide fibers with a high doping concentration is presented. A 6-level amplifier system that incorporated clustering-induced concentration quenching, cooperative upconversion, pump excited state absorption (ESA), and signal ESA, was adopted for the modeling. The accuracy of the modeling was verified by comparing the calculated gain and noise figure with experimentally obtained ones.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.289-294
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• 2008

Affordable traffic capacity of each node in networks is expected to reach in Tb/s range in proportion to the rapid growth of Internet users. To transmit more than Tb/s per fiber pair, WDM should be used as well as existing TDM. To increase the capacity of transmission in WDM networks, there are two ways, increasing channel speed or channel quantity. To increase the channel quantity, there are two ways, narrow spacing or expanding transmission bandwidth. To expand bandwidth, ultra-broadband optical amplifier technology is necessary. In this paper, we introduce EDFA in effect at C/L band, FRA, and some optical amplifiers in effect at S band, and analyze the development trend of various amplification technologies.

• The Magazine of the IEIE
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• v.21 no.2
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• pp.8-19
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• 1994

• Electrical & Electronic Materials
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• v.23 no.2
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• pp.14-21
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• 2010

• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.245-251
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• 2022

We have developed a multi-channel fiber laser for tiled laser beam combining and a laser output array system for multi-beam alignment. The fiber laser is a master oscillator power amplifier configuration that has a common seed, a preamplifier, and a 7-channel amplifier. The output power of each channel is more than 10 W. The laser output array system is a packed cylindrical configuration for a high fill-factor, and it has capabilities for collimation and tilt control with built-in PZT. Multi-beam alignment to a target is successfully implemented using PZT controlled with a stochastic parallel gradient descent (SPGD) algorithm.

• Optical Science and Technology
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• v.8 no.3
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• pp.30-39
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• 2004

파장분할다중화(WDM) 방식은 그 풍부한 수용능력 때문에 늘어나는 인터넷 망 또는 고품질 통신망의 대용량 정보수요를 충족할 수 있는 최상의 해법이다. WDM 방식을 이용한 광전송시스템은 관리가 용이하고 설치비가 저렴하여, 최근 십여년 간 집중적으로 연구 개발되어지고 있다. 수 년 전까지도 이 분야의 주된 연구목적은 WDM 채널간의 최소간격을 1000Hz로 고정하고 채널 수를 늘려서 전체 광전송 용량을 증가시키려는 것이었다. 그러나 점차 광섬유의 손실을 보상하기 위해 사용되는 광섬유 증폭기의 비용부담이 증가하면서 채널간격을 줄여 대역효율을 높이는 전송기술이 연구되고 있다.(중략)

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.16-21
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• 2007

CMOS variable gain amplifier (VGA) IC designs for the structure monitoring systems of the telemetries were developed. A three stage cascaded VGA using a differential amplifier and a linear-in-dB controller is presented. A proposed VGA is a modified version of a conventional VGA such that the gain is controlled in a linear-in-dB fashion through the current ratio. The proposed VGA circuit introduced in this paper has a dynamic range of 77 dB with 1.5 dB gain steps. It also achieved a gain error of less than 1.5 dB over 77 dB gain range. The VGA can operate up to 10MHz dissipating 13.8 mW from a single 1.8 V supply. The core area of the VGA fabricated in a Magnachip $0.18{\mu}m$ standard CMOS process was about $430{\mu}m{\times}350{\mu}m$. According to measurement results, we can verify that the proposed method is reasonable with regard to the enhancement of dynamic range and the better linear-in-dB characteristics.