• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.1-7
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• 2000

Generally, one-dimensional fiber optic code-division multiple-access(CDMA) system is encoded and decoded using optical orthogonal codes(OOC’s), where two-dimensional fiber optic CDMA system uses optical orthogonal signature pattern codes(OOSPC’s) for parallel data link process. The OOSPC’s should have good autocorrelation and cross-correlation properties. However, if timing information or synchronization of OOSPC’s can be obtained by other means, the property of autocorrelation may not be restricted and we can increase the number of pattern codes. In this paper we introduce the fiber optic CDMA system for parallel transmission of two-dimensional data and investigate methods of generation of two-dimensional pattern codes. The probability density function of interference noise is calculated in interfering OOSPC’s of the users and the corresponding bit error rate is derived.. We compare each OOSPC’s by plotting bit error rate versus threshold values and the number of simultaneous users, from the result, we propose the optimal OOSPC’s conditions for the parallel transmission of two-dimensional data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1348-1356
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• 1991

The need for MAN(Metropolitan Area Network)has been increased by demands for high performance comuter communication. According to the definition of MAN by IEEE 802.6 MANs have diameter of about 50km, bandwidth of more than 1Mbps, and limited delay, Because optical fibers have unique characteristics that make them attractive for the implementation of MANs several fiber optic networks suitable for MAN application have been proposed. Those networks have drawbacks such as unlimited delay, many processing nodes and limited number of stations. Also IEEE 802.6 proposals and oters improved networks were proposed, but they have complicated access procedures and data buffering and difficulties in implementation. This paper descrives the design of Fiber Optic Metropolitan Area Network in Seoul(Seoul FOMAN) to overcome the drawback, Seoul FOMAN is hierarchical MAN and designed based on the topology of 43 end offices in Seoul. We propose MAN topology, proper access protocol and analyze the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1542-1550
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• 2000

Fiber optic link systems based on SCM scheme are widely used as efficient and economic RF signal links between base station and a central station in mobile communication networks. However, its performance can be seriously limited depending on the operational conditions of not only the optical transmission system but also the wireless link in various environments. In this paper, we propose an analytic model for performance analyses of the SCM fiber optic link for CDMA RF signal transmission in various link environments. We present optimal operational conditions taking account of the nonlinear effects of the optical transmission system, and the multiple access interference produced at the wireless link. It has been shown through the BER analyses in this paper that the selection of optical modulation index of the SCM fiber optic links can be found optimally to minimize the fiber optic link noises and intermodulation distortion due to LD.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.4
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• pp.5-16
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• 2003

We have analyzed the performance of optical matched filters in the fiber-optic code division multiple access (FO-CDMA) system based on optical parallel coupler access encoder (PCAE) and parallel coupler access decoder (PCAD) by experiment. In previous studies, the performance evaluation of the FO-CDMA system using SCAE and SCAD was not sufficiently accurate because they analyzed system performance only considering the first order signals. Since optical SCAE and SCAD intrinsically have high order signals of various patterns as the number of coupler increases, they change auto- and cross-correlation intensities. Thus, it is necessary to investigate properties of the PCAE and PCAD so that we may analyze the exact performance of system. In this paper, it is found that the peak to sidelobe ratio using the PCAE and PCAD increases as $\alpha$ (coupling coefficient) value increases. Also, we found that the proposed PCAE and PCAD are superior to SCAE and SCAD in performance improvement.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.432-432
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• 2004

• ETRI Journal
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• v.23 no.3
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• pp.106-110
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• 2001

Subpicosecond all-optical switching method based on the simultaneous two-photon coherence exchange is proposed and numerically demonstrated. The optical switching mechanism is based on the optical field induced dark resonance swapping via nondegenerate four-wave mixing processes. For potential applications of ultrafast all-optical switching in fiber-optic communications, 10-THz channel number independent quantum router is discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.9-14
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• 2002

Ferrule is widely used as fiber optic connecters. In fiber-optic communications, the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin, pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule center is investigated in the case where cone-shaped center pins and round circle hales which make contact with each other near the edge of the holes, using homeogenous coordinate transformation and numerical analysis. The obtained results are as follows: The alignment errors between center pins alone do not affect the rotation accuracy of ferrule. The alignment errors between center holes cause a sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers increase in proportion to the center pin angle in the case of a fixed alignment errors

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1304-1316
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• 1996

In this paper, A VCO(Voltage Controlled Oscillator) in use of clock recovery/data regeneration circuit for 10 Gbps fiber optic receivers was developed. The improved hair-pin resonator with a parallel coupled lines, which has been applied to microstrip filters, was used as a resonance part. As a frequcncy tuning device by substituting 3-terminalMESFET vaaractor for varactor diode, an MMIC manufacturing process will be simplified. Since a hair-pin resonator is planar type compared to the dielectric resonator and has a relatively flat reactance verus frequency, it will be favorable to apply a hair-pin resonator to an MMIC, in addition wideband frequency tuning range is able to be obtained.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.987-991
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• 2003

Ferrule is widely used as fiber optic connecters. In fiber-optic communications, the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin, pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule center is investigated in the case where cone-shaped center pins and round circle holes which make contact with each other near the edge of the holes, using homeogenous coordinate transformation and numerical analysis. The obtained results are as follows: The alignment errors between center holes cause a sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers increase in proportion to the center pin angle. The relationship between center pins displacement in coaxial grinding and grinding accuracy was explained.

• 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.