• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.59-67
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• 2006

We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1369-1375
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• 2007

The recent, a large capacity of telecommunication networks is required in order to it is in proportion to capacity of information communication increase and to satisfy a demand because of the demand about Internet, a multimedia service of internet, Video of internet protocol(VoIP), Audio/Video streaming. As a result, DWDM(Dense Wavelength Division Multiplexing)technologies are emerging to be a prevailing the method of solving it without additional optical fiber network building and high-speed equipment. Therefore this thesis proposed the optical filter of fiber/multilayer slab coupled structure combining it to multilayer slab waveguide by polishing the cladding of one side of fiber to design the optical filter having these functions. When a separation distance of fiber and slab was $3{\mu}m$, The optical filter proposed as the simulation result was satisfied with a DWDM filter characteristic with FWHM of 0.1nm on TM mode and TE mode as 32nm polarization independence in a communication window of $1.3{\mu}m$ when center wavelength was each ${\lambda}_0=1.274755{\mu}m$ and ${\lambda}_0=1.30591{\mu}m$.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.453-456
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• 2003

DWDM(Dense Wavelength Division Multiplexing) 기반의 광 네트워크가 범 세계적인 차세대 광 인터넷(NGOI: Next Generation Optical Internet) 백본망의 대안으로 인식되고 있으나, 기존의 전기적인 오버헤드 비트를 이용한 전송 관리 정보의 사용이 더 이상 유효하지 않아 장애 관리에 많은 문제점을 드러내고 있다. 본 논문에서는 NGOI 백본망의 링크 관리를 위해 광 성능 모니터링 시스템 및. GMPLS(Generalized Multi-Protocol Label Switching)의 링크 관리 프로토콜(LMP: Link Management Protocol)을 활용한 관리 모델을 제시한다.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.237-240
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• 2001

Dense Wavelength division multiplexing(DWDM) lightwave system requires multiplexer, demultiplexer and optical filter. In this paper, thus, we propose the Add-Drop Mux/Demux based on a Mach-Zehnder interferometer(MZI) with fiber Bragg grating(FBG). The Add-Drop Mux/Demux using FBG and MZI is able to minimize system and reduce weight. We also analyze output characteristics of Add-Drop Mux/Demux and present the optimum design data through the computer simulation.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.124-128
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• 2014

We derive joint probability density functions (JPDFs) for two adjacent data from direct-detection optical receivers in dense wavelength-division multiplexing systems. We show that the decision using two data per bit can increase the receiver sensitivity compared with the conventional decision. Our JPDFs can be used for software-defined optical receivers enhancing the receiver sensitivities for intensity-modulated channels.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.184-185
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• 2001

장주기 광섬유격자는 최근 급속한 발전을 하고 있는 DWDM (Dense Wavelength Division Multiplexing) 시스템에 이득평탄화 필터 및 다중 채널 필터 등으로 활발히 연구되고 있다. 장주기격자는 광섬유 코아를 따라 진행하는 모드를 다수의 크래드 모드로 결합시키는 소자로서 그 응용이 다양할 뿐만 아니라 광섬유 내의 모드결합 현상을 이해하는데도 좋은 예를 제공하고 있다. 본 연구에서는 광섬유에서의 모드결합을 단순한 기하광학적 방법으로 간단히 해석하는 방법을 제시한다. (중략)

• Journal of Korea Multimedia Society
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• v.14 no.5
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• pp.658-668
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• 2011

Over the past decade, the improvement of communications technologies and the rapid spread of www (World Wide Web) have brought on the exponential growth of users using Internet and real time multimedia multicast services like video conferencing, tele-immersive virtual reality, and Internet games. The dense-wavelength division multiplexing (DWDM) networks have been widely accepted as a promising approach to meet the ever-increasing bandwidth demands of Internet users, especially in next generation Internet backbone networks for nation-wide or global coverage. A major challenge in the next generation Internet backbone networks based on DWDM technologies is the resolution of the multicasting RWA (Routing and Wavelength Assignment) problem; given a set of wavelengths in the DWDM network, we set up light-paths by routing and assigning a wavelength for each connection so that the multicast connections are set-upped as many as possible. Finding such optimal multicast connections has been proven to be Non-deterministic Polynomial-time-complete. In this paper, we suggest a new heuristic multicast routing and wavelength assignment method for multicast sessions called DVS-PMIPMR (Differentiated Virtual Source-based Priority Minimum Interference Path Multicast Routing algorithm). We measured the performance of the proposed algorithm in terms of number of wavelength and wavelength channel. The simulation results demonstrate that DVS-PMIPMR algorithm is superior to previous multicast routing algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.568-574
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• 2009

320km optical transmission link for 128 channel DWDM (dense wavelength-division-multiplexing) signals is simulated and fabricated. An optical fiber amplifier for the link is composed of a distributed Raman amplifier and dual C/L-band EDFAs which are optimized for the performances of an optical amplifier obtained from the simulation. Gain and NF of the optimized EDFAs are above 19dB and below 7.5dB, respectively. The resultant OSNRs (optical signal to noise ratios) of the link are average 25dB on each band.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.354-360
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• 2009

We investigate theoretically the tolerance of 40 Gbps phase-modulated (PM) duobinary signals using a vestigial sideband (VSB) filter on impairments which occurred in dense wavelength-division multiplexing (DWDM) systems, compared to the conventional duobinary signals. Our simulation results show that PM duobinary signals can't have the gain on the spectral efficiency achieved by utilizing the VSB filtering technique. In order to increase the spectral efficiency, they indispensably require to be transmitted at the optimum bandwidth of multiplexer (MUX) and demultiplexer (DEMUX) since they are susceptible to inter-channel crosstalk. It is also shown that the PM duobinary modulation format has a large tolerance on self-phase modulation (SPM) and cross-phase modulation (XPM) under the condition which MUX and DEMUX have been tuned at an optimum bandwidth; it has 1.2 dB power penalty at the fiber launching power (FLP) of 15 dBm and the channel spacing of 50 GHz.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.105-108
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• 2003

In the next generation backbone networks based on dense-wavelength division multiplexing (DWDM), the routing and wavelength assignment with quality-of-service (QoS) recovery is essentially needed to support a wide range of communication-intensive and real-time multimedia services. This paper proposes a new dpmic routing method called as MW-MIPR (MultiWavelength-Minimum Interference Path Routing), which chooses a route that does not interfere too much with many potential future connection requests. This paper also proposes a differentiated RWA mechanisms combined with MW-MIPR algorithm to provide QoS recovery for various multimedia applications in the next generation backbone networks based on DWDM.