• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1255-1260
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• 2003

In order to reduce driving power consumption, we propose and fabricate a new structure of asymmetric SOI 1${\times}$2 thermo-optic switch that has a back side silicon trenched structure. Compared to conventional SOI thermo optic switches without heat sink structure, it shows an improvement of switching power reduction from about 4 watt to 1.8 watt without sacrificing cross talk of about 20 ㏈ at the light wavelength of 1.55 $\mu\textrm{m}$. Here we also described the main design consideration and fabrication procedure for the proposed device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.744-749
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• 2016

This paper presents the design of a computer-generated hologram for beam control of an LCOS-based wavelength selective switch, which is the core technology for next-generation ROADM. By introducing a computer-generated hologram instead of general grating patterns to control the LCOS device, we contribute to building a more efficient wavelength selective switch. With the use of phase modulation properties of LCOS devices, we designed the hologram for five-port output and a 40-channel wavelength selective switch. We applied a multi-level phase modulation technique with the Gerchberg-Saxton algorithm to produce the hologram, which is easily scalable to any different type of wavelength selective switch. With an experimental setup, we verified the usability of the hologram designed for five-port output. We also suggest a hologram design technique for beam control of a 40-channel wavelength selective switch.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.77-83
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• 2012

Since power system is switching to smart grid, on-line monitoring technology has become necessary for underground distribution power cable. Therefore, the application of DTS(Distributed Temperature Sensing) technology using OFCPC(Optical Fiber Composite Power Cable) capable of monitoring underground distribution power cables has been developed. These can bring about reductions in faults and increases in operating capacity of underground distribution system. To date, the test-bed of optical fiber composite power cable on-line monitoring system has been constructed. Then, matters to be improved have been drawn through verification experiments. This paper presents the improvement and experiment results of the optical fiber composite power cable on-line monitoring system to apply to underground distribution lines in the field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1722-1731
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• 2000

In this paper we proposed a new type of the Optical Cell Compressor and Decompressor which are essential modules in TDM of TDM/WDM Hybrid OPtical ATM Switch structure. This proposed structure frastically lessens hardwares for realization by using SOA gates and optical feedback loops in the process of compression and decompression. Also it is able to compress and decompress the large capacity optical pulse stream just with a few of stages cascade connected. We proved it's possibility for systematic application through 4-bit compression experiment.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.15-21
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• 1999

The scalability of optical cross-connect nodes is analyzed based on the limiting factor of transmission performance. The limiting factors considered are ASE noise accumulation and gain saturation in the optical amplifiers, and crosstalk in both wavelength multiplexers/demultiplexers and optical switches. When the wavelength multiplexer/demultiplexers crosstalk is lower than 25dB, Power Penalty is below 1dB for the cascaded transmission of 10 nodes with 4 input/output ports. When 10Gbps signals are transmitted through nodes with 4 and 16 input/output Ports, performance degradation due to switch crosstalk is dominant compared to that due to ASE noise accumulation if the switch crosstalk is larger than 30dB and 45dB, respectively. For the single stage transmission of 10Gbps signal with 21dB fiber link loss, the maximum loss of optical cross-connect nodes must be under 34dB to achieve the BER of $10^{-12}$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.8
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• pp.543-548
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• 2003

In this paper, we have proposed and fabricated a two-axis rotational micro-mirror with large tilt angle. Such a micro-mirror is a key element for N$\times$N high capacity optical cross-connect switches. The micro-mirror is required to have large tilt angle to increase the capacity of the cross-connect switches. For larger micro-mirror tilt angle between the grounded mirror plate and the bottom electrode is to be large enough to provide space for the tilting of the mirror. For our proposed structure, the gap was produced in such a way that the grounded mirror plate and the bottom electrode were made separately in different substrates by using the bulk micromachining technology, and combined later by employing self-align technique. As a result, a large tilt angle has been achieved without using additional actuators. The measured tilt angles were as large as $\pm$5.5$^{\circ}$ and $\pm$8.4$^{\circ}$ in the x and y direction respectively, and the pull-in voltages for the two directions were 380 V and 275 V respectively. Finally the fabricated mirror was successfully utilized to steer the optical beam. To our knowledge, our micro-mirror has the best performance among the micro-mirrors reported internationally so far.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.33-37
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• 2003

A low-power $1{\times}2$ polymeric thermo-optic switch with a trench structure is proposed and fabricated. The trench structure in the optimized region slows down the heat flow from the electrodes, which contributes to the reduction of power consumption. The temperature distribution in the polymer layers has been adjusted to increase the temperature gradient between the two arms of the Y-branch. For comparison, a $1{\times}2$ polymeric thermo-optic switch with no trench structure is fabricated together on the same substrate. In the device with a trench structure, the measured crosstalk is less than -17.0 dB for TE polarization.-15.0 dB for TM polarization. The power consumption is about 66 mW, which is 25% less than that of the device with no trench structure.

• ETRI Journal
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• v.43 no.5
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• pp.799-811
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• 2021

This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/ node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels (𝛾_w) equal to 35.72 %, 39.09 %, and 36.93 % compared to shortest path first routing and 𝛾_w equal to 29.41 %, 37.35 %, and 27.47 % compared to alternate routing in three different networks.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.214-215
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• 2000

레이저로 발생시킨 플라즈마의 분광학적인 분석은 유용한 분석기술로 평가되고 있다. 이러한 플라즈마를 발생시키는데 있어서 Q-switched 레이저를 많이 사용되고 되고 있으나, Q-switch된 레이저로 발생시킨 플라즈마 복사광의 특성은 주변 분위기에 의해 매우 큰 영향을 받는다. 특히 대기압인 공기분위기에서 레이저로 발생된 플라즈마의 분광특성은 강하고 연속적인 background가 포함되고, 자체적으로 흡수되고, 넓게 퍼진 분광선들이 생성된다. 이는 레이저 발생 플라즈마를 통해 성분을 분석할 경우에 적합하지 않다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.258-259
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• 2002

광회선 분배 시스템(OXC)은 전광통신망(Optical Transport Network)에서 광신호 간 연결을 원격으로 설정해 줄 수 있는 노드(Optical Network Element)이다. OXC는 다수의 입력/출력 링크를 가지며 하나의 입력/출력 링크에는 다수의 파장 다중된 광신호 채널이 존재한다. OXC는 하나의 입력 링크를 통하여 입력되는 다수의 파장 채널을 서로 다른 출력 링크로 연결해 주거나, 다수의 입력 링크로부터 입력되는 파장채널을 하나의 출력 링크로 연곁해 줄 수 있는 optical grooming 기능을 수행한다. 또한 자국에서 광신호를 Add/Drop할 수 있는 기능을 가질 수 있다. (중략)