• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.723-725
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• 2013

The compensation characteristics are investigated as a function of the position an optical phase conjugation (OPC) in the optical transmission links with a randomly distributed residual dispersion per span (RDPS). The simulation results show that the optimal net residual dispersion (NRD) is decided to be 10 ps/nm and -10 ps/nm by precompensation and postcompensation, respectively, which are independence of the OPC positions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.4
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• pp.335-346
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• 1987

The principal reason for the backscattering in an optical fiber is the Rayleigh scattering which is caused by non-uniform density of structure material of an optical fiber and diameter variations of the optical fiber-core along an optical fiber axis. The backscattering signal which is detected by the optical time domain reflectometer system(O.T.D.R) conatains information about both tha actual decay of power and the diameter variation along the optical fiber. In this paper, the O.T.D.R. system with 2x2 fiber directional coupler, timing control unit and gated integrator is used to measure diameter variations of an optical fiber.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1484-1493
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• 1992

In this paper, we propose the polarization coding of optical logic gates using filters and LCTV's, and represent the real-time system of an optical parallel adder to improve a carry propagation delay time. We fabricated a polarization filter for the polarization coding of a cell and an electrical system instead of an optical flip-flop which was necessary to an optical parallel adder. We used an optical fiber to play a part of decoding mask and interconnections in an optical parallel adder. The experimental results show that the polarization coding of a cell can represent 16 optical logic functions and that the implemented optical parallel adder can operate in real-time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.826-833
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• 2002

Generally, it is announced that RZ pattern gives a better transmission performance than NRZ pattern in ultra-high speed transmission above 10Gbps. In this paper, we propose a wavelength converter for RZ data which can controls XPM in SOA by locating polarization controllers within optical fiber loop mirror and demonstrate its performance through simulation and 10Gbps data experiment. The proposed structure needs only one polarization dependent SOA for implementation compared to previous XPM ones to make the cost down. And it provides non-inverted pattern outputs at two output ports respectively.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.89-94
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• 2017

This paper presents a theoretical study of transmission performance for optical duobinary transmitters employed a Mach-Zehnder modulator. Especially, we have investigated the performance of the various transmitters for transmitting 25Gbps optical duobinary signals at a wavelength of 1550nm without any dispersion compensation methods over single mode fiber. Due to the characteristics of generating their duobinary signals, each transmitter has a distinct optical power spectrum and an eye opening shape. By these, there was a difference in the dispersion tolerance. We could find a suitable transmitter for 25Gbps transmission considering the structure complexities and the restricted conditions with the simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.975-977
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• 2013

The optimal distribution pattern is induced in the optical link with an artificial distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS). It is confirmed that the descending distribution of SMF length and ascending distribution of RDPS are most suitable to compensate for the distorted WDM signals, as the fiber span number is more increased. in the optical link with 10 ps/nm or -10 ps/nm the optimal net residual dispersion (NRD).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.964-966
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• 2015

The effect of the deviations of single mode fiber lengths and residual dispersion per span (RDPS) on the compensation for the distorted WDM signals in the dispersion-managed optical links with the specially artificial distributions of the lengths of SMFs and RDPSs. The considered artificial distribution is following; the lengths of SMF and RDPSs between the adjacent fiber span are more descended in the half transmission section from transmitter to optical phase conjugator (OPC), and those are more ascended in the rest half transmission section from OPC to the receiver, as number of fiber spans are more increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.657-662
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• 2003

The OPM(optical performance monitoring module) is needed in order to monitor optical performance. the most importance of OPM is to measure the wavelength of optical signal. In the past time, it was very difficult to get the wavelength value because they used pilot tone. Since then, using AWG(arrayed waveguide grating) and AOTF(acousto optic tuneable filter), the wavelength and the transmission qualify for multi channel signal have been monitored. In this paper, we chose the fiber fabry-perot wavelength variable filter which be evaluated for optical resolution ability to excellent, so that FBG(fiber bragg grating) was used for setting reference wavelength because chose a wavelength variable filter.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.2
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• pp.90-95
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• 2009

All-optical fiber-type gain flattening filer (GFF) for an EDFA (Erbium doped fiber amplifier) were fabricated by using a FBT (fiber biconical tapered) process and the performance of the GFF was tested and athermal package was proposed. Historically, the chief contributor to gain unevenness has been the EDFA. Due to the inherent gain response of the EDFA's operation, there is always a modest imbalance in the gain applied as a function of wavelength. FBT methods have been used to make fiber type couplers and WDM filter since 1980. Attractivity of this methods was simple, cost effective and thermal stability. Simulation program tool is made to design target GFF profile for this paper. Fiber coupler manufacturing machine is modified for the GFF process. The final GFF is obtained by cascading 4 unit filter that has 6 taper stage. Test result shows 1 dB of wavelength flatness in the C band. Polarization dependent loss is under 0.15dB. The center wavelength variation is below ${\pm}$0.35nm at the temperature range of $20^{\circ}C$ to $70^{\circ}C$.