• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.287-291
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• 2013

The low- frequency hydrophone sensor, using the recently developed FBG has an excellent merits which the existing fiber-optic sensor has and also it has an excellent signal sensing effect in the environment of low-frequency(30Hz-300Hz), not to be detected by the PZT sensor. we have the detection of frequency 19KHz right signals when was using more Hopper lenz WDM than $1{\times}3$ optical coupler. furthermore, we can expect the uitilization of low-frequency signal detection to be used for the military purpose and also it can be developed as the high-sensibility multiplexing through the sensor array system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.119-127
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• 2004

This paper reports on the simulation study of gigabit-capable Passive Optical networks (GPON) using WDM focused on single light source per each channel, and proposes using 1550nm VCSEL for light sources. Proposed system uses high speed direct-modulated light sources, in which the merit is able to maintain a low loss. to support broad bandwidth, and to lower network configuration cost. We conformed simulation study on the transmission of the downstream 2.5Gbit/s, upstream 1.25Gbit/s, 622Mbit/s which was recommended by ITU-T G.984.1. We measured the transmission margin and examined the feasibility of proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.573-578
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• 2000

This paper presents a noble optical access system using shared laser and LED light sources, which is based on WDM-PON technologies. This system adopts an external modulation of the shared laser sources for high-speed downstream and a direct modulation of the LED sources for low-speed upstream. To split or combine the transmission channels, AWG(Arrayed Wave-guide Grating) devices are used in the optical cable section. The proposed system is attractive for low cost implementation. The laser light sources can share the optical carriers in the downstream scheme. Also, in upstream, the LED sources can afford to make simple of the circuits for controlling light source and of standardization for ONU(Optical Network Unit). The feasibility of the proposed system is demonstrated by several experiments. Our results show that the system operates well at 2.SGbps for downstream and up to 622.08Mbps for upstream.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1157-1166
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• 2001

In this paper, we investigated the degree of compensation for optical pulse shape distortion due to both chromatic dispersion and SPM(self phase modulation) in high speed optical transmission system with dispersion shift fiber. We adopted the power symmetric MSSI(mid-span spectral inversion) as compensation method. We used EOP(eye-opening penalty) parameter in order to evaluate the compensation efficiency of distorted optical pulse. We evaluated input signal power range being able to maintain stable reception performance in the case of various chirp parameter of modulated optical pulse. And, in order to verify the applicable to wideband WDM system, we evaluated the wavelength range being able to maintain stable reception performance through the EOP calculation of various dispersion coefficient of first fiber D$\_$11/. We showed that proposed MSSI is effective compensation method to down chirped optical pulse transmission rather than up chirped optical pulse transmission in anomalous dispersion range. And we showed that this method have possibility of relative high power transmission and wideband transmission in WDM system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1234-1242
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• 2004

In this paper, the characteristics of compensation for interferenced mid-channel signal by neighbor channels through four-wave mixing (FWM) process dominantly is investigated as a function of channel input power, fiber dispersion coefficient and transmission length in WDM system with equally spaced channels. The compensation method used in this research is mid-span spectral inversion(MSSI). The highly nonlinear dispersion shifted fiber (HNL-DSF) is used as a nonlinear medium of optical phase conjugator (OPC) in order to compensate wideband WDM signals. First, we confirmed that the effect of FWM on channel interference is gradually reduced as fiber dispersion coefficient becomes gradually smaller, independent of signal format. And, we confirmed that RZ is better than NRZ as a modulation format for transmitting high power channel with allowable reception quality. But realization of flexible WDM systems regardless of channel number variation is possible by using NRZ rather than RZ format.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.233-240
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• 2005

In this paper, we have shown the gain recovery time of erbium-doped fiber amplifier(EDFA) in WDM add/drop networks can be reduced to less than $3\mu$sec by employing disturbance observer technique with PID controller which is based on 3-level EBFA model. The $3\mu$sec transient time is the fastest one ever reported and it is about $1\%$ of $250\mu$sec previously obtained from disturbance observer technique with PI controller which was based on 2-level EDFA model and it is also less than $200\mu$sec of commercially available EDFAs for WDM networks. We were able to obtain this result by analyzing various system characteristics as we change the parameters of disturbance observer and PID controller. If this result is applied to a commercial product, the product will do an important role in the future dynamic WDM networks.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.9-14
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• 2004

Lightwave communication system for Wavelength division multiplexing(WDM) consists of multiplexer, demultiplexer and optical Inter. But, the existing multiplexer, demultiplexer and optical filter is difficult to minimize system and reduce weight because they are not integrated device type. In this paper, thus, we propose the OADM baed on a Mach-Zehnder interferometer(MZI) with FBG(fiber Bragg Slating) in the interferometer Ems. The OADM using FBG. and MZI is able to minimize system and reduce weight. We analyze output characteristics of OADM and present the optimum design data through the computer simulation and experimentation. Also unposed OADM fits for DWDM(Dense WDM) system because of wide bandwidth by tuning narrow linewidth.

• Journal of Applied Reliability
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• v.1 no.2
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• pp.121-138
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• 2001

Due to large demand for high speed and great capacity for data transfer, WDM, which uses the wavelength division multiplexing technique, is known as alternative way to satisfy those demand for its flexible network operation and management, easy network expansion with existing networks, and enhancement of efficient data transfer rate. For these reasons, a new high capacity WDM optical communication network plan was established. Therefore, the quality of currently deployed optical cables with 81.6 km in length should be assessed to ensure if high capacity WDM system could be implemented on existing optical cables. Two important characteristic parameters, Transfer Loss and PMD (Polarization Mode Dispersion), were measured to evaluate quality of existing optical cable. Transfer Loss was measured at 0.244 dB per kilometer, which is lower than the design standard value at 0.275 dB/km. The measured PMD value gave at 0.030ps/km, and it, therefore, satisfies the value recommended by ITU-T (International Telecommunication Union-T) of 0.5ps/km. In addition, the transfer characteristic for existing 2.5 Gbps and 10 Gbps system were measured and evaluated, and the results showed that error-free transfer is very much feasible. Computer simulation for DWDM system, which is likely be a future backbone network in Korea, to assess the transfer characteristic using the same condition employed for 2.5 Gbps and 10 Gbps was carried out as well. The simulation verified that a stable network operation and reliable service could be provided.

• The Journal of the Korea Contents Association
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• v.6 no.7
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• pp.69-78
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• 2006

In this paper, we presents the efficiency and a transmission quality of the system which is composed of the optical elements from physical layer of the active optical ring network. For a simulation it will use the Transmissionmaker WDM and it will be able to observation a optical transmission quality of the optical transmission system. The active optical network is composed of two rings(main ring and sub-ring). It measures the BER(Bit Error Rate) quality which it follows node number from the sub ring and physical distance of the node. Performance analysis from the physical layer becomes the standard of the plan for the efficiency optimization of the active optical ring network. Consequently it will be able to compose the efficient optical transmission system which reflects the physical distance, a traffic demand quantity of each node and a number of users from actual network.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.187-192
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• 2017

The compensation characteristics of the distorted WDM channels compensated for by dispersion management (DM) and optical phase conjugation in the long-haul (50 fiber spans ${\times}80km$) transmission link with the randomly distributed single mode fiber (SMF) length and residual dispersion per spans (RDPS) are investigated as a function of the arrangement of SMF and dispersion compensating fiber (DCF) and the control position of net residual dispersion (NRD). It is confirmed that the compensation effect of the distorted WDM channels strongly depends on the arragement of SMF and DCF, rather than the control position of NRD.