• 한국공작기계학회논문집
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• 제16권5호
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• pp.145-150
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• 2007

Optical communication according to request of technology of communications and optical fiber to be full filed faster communication and pass over transmission capacity limit per unit area, per unit hour appeared, and this optical fiber acts the biggest role to influence performance of optical communication network. Optical fiber(PMF Polarization Maintaining Fiber) is used, and is used by electric field measurement, self-discipline measurement, sensor(Sensor) Department by high definition measure such as thermometry and storehouse component that use because make broad sense status and polarized light information in passageway and union with storehouse integrated circuit etc. that use broad sense interference developing could transmit in state that keep transmitting broad sense plane of polarization is polarized light existence. Also, research is developed by optical fiber for Coherent communication recently.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.203-209
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• 2012

Visible light communications (VLC) use modern solid-state light-emitting diodes (LEDs) to broadcast information. Emerging white-light LEDs allow the combination of lighting and optical wireless communication in one optical source. In this paper, a new LED lighting design using one-chip-type white LEDs is proposed for efficient illumination and optical wireless communications under the existence of several obstacles. Lighting and communication performance are analyzed to show the effectiveness of the proposed LED lighting. Specifically, the signal-to-noise ratio considering intersymbol interference and the bit-error rate of variable pulse position modulation (VPPM) with dimming control are considered.

• Current Optics and Photonics
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• 제1권6호
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• pp.579-586
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• 2017

In this paper, we theoretically demonstrate that semiconductor optical amplifiers (SOAs) with strong wavelength dependence of gain and phase are capable of all-optical inverted and non-inverted wavelength conversion (WC) over a wide range, with the assistance of an optical filter. First, the gain dynamics and phase dynamics in a common quantum well (QW) SOA with the $In_{0.53}Ga_{0.47}As/In_{0.7322}Ga_{0.2678}As_{0.5810}P_{0.4190}$ material system are found to be strongly dependent on wavelength, which is mainly related to the wavelength dependence of the differential gain and the differential refractive-index change. Second, the wavelength dependence in an all-optical wavelength converter based on the QW SOA cascaded with a detuning band pass filter is studied. Simulations show that the quality of the converted signal has little dependence on the operation wavelength. Both inverted and non-inverted WC can be achieved, over a large wavelength range. Therefore, although the gain and phase change are strongly wavelength-dependent, the effects of this dependence can be erased by appropriate optical filtering.

• Journal of Astronomy and Space Sciences
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• 제37권1호
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• pp.11-18
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• 2020

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

• 한국인쇄학회지
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• 제29권3호
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• pp.97-104
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• 2011

The storing ability of information of optical disks directly depends on the physical property of recording unit cells. It means that the degradation of optical disks ultimately causes the loss of the physical and chemical properties of recording unit cells and leads also information, too. We investigated the degradation and life time of optical disks which tell us the longevity of the preservation of information. Optical disks were aged using the accelerated aging system and studied by optical reflectivity spectroscopy and atomic force microscopy(AFM), and the preservation environment of electronic media in National central library of Korea also were analysed. Results show that the double reflective coated optical disks have good preservation of recording information but revealed some deformation of dye area in the AFM images. It means that we should include the mechanical and chemical degradation of the optical disks in the life time expectation evaluation.

• Current Optics and Photonics
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• 제7권1호
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• pp.15-20
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• 2023

We propose a new coherent optical receiver (COR) to detect optical receiver mode (ORM) subchannels selectively in coherent optical (CO) ORM division multiplexing (ORMDM) systems. In the CO-ORMDM systems, each optical channel is a linear sum of ORM subchannels, to obtain high spectral efficiencies (SEs). The COR uses an ORM subcarrier as its local oscillator (LO) and reads the transmitted data at the origin times of ORM signals. For example, if the m^th ORM subcarrier is used as the LO, then the COR reads the data of the m^th ORM subchannel. The proposed COR is fast and can make CO-ORMDM systems useful for real-time optical communication with high SE.

• 한국전자통신학회논문지
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• 제1권1호
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• pp.63-69
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• 2006

해저광케이블은 육상광케이블에 비해 장거리이며 광중계기 시스템으로 인해 흔히 사용하는 고장지점에서 후방으로 산란 빛으로 거리를 탐지하는 일반적인 OTDR(Optical Time Domain Reflectormeter)의 사용은 매우 제한적이다. 그래서 해저광케이블 시스템에서 광코어의 단선인 경우는 광중계기의 OTDR Path를 이용한 Coherent OTDR를 사용 고장위치 탐지하고, 광신호의 증폭을 위해 광중계기에 필요한 전력을 공급하는 해저광케이블 내의 동튜브(Copper Tube) 손상시에는 전류/전압특성, 단위정전용량등을 이용한 방법들이 사용된다. 이런 정보를 이용하여 해저광케이블의 고장 형태에 따른 적절한 탐지 기법을 제시하고자 한다.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.557-562
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• 2016

In this paper, for the first time, the transmission performances of long-haul 100-Gb/s direct detection optical OFDM (DDO-OFDM) and coherent optical OFDM (CO-OFDM) wavelength division multiplexing (WDM) systems are compared by simulation. It provides specific guides for system parameter selection to get a high-performance and cost-effective OFDM WDM system. Specifically, the comparison involves three aspects: launched power is investigated to achieve better system performance; laser linewidth is numerically investigated to choose cost-effective laser; system dispersion tolerances with different laser linewidths are analyzed to further reveal the advantages and disadvantages of these two detecting methods, direct detection and coherent detection, in long-haul OFDM WDM system.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.145-148
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• 2007

In this paper, we discuss a study on Advanced TCA(ATCA) based 40 Gbps level Optical transport platform having 120 Gbps(12, 10 Gbps modules) switching capacity as an OTP based large capacity multi service technology. The ATCA-based OTP(Optical Transport Platform) is composed of OTH(Optical Transport Hierarchy) 10 or 40 Gbps client signal interface module, OTH 10 Gbps transport module, high-rate OTH unit switch, system processor, and can be installed in ATCA platform.

• ETRI Journal
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• 제34권1호
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• pp.122-125
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• 2012

A video signal through a high-density optical link has been demonstrated to show the reliability of optical link for high-data-rate transmission. To reduce optical point-to-point links, an electrical link has been utilized for control and clock signaling. The latency and flicker with background noise occurred during the transferring of data across the optical link due to electrical-to-optical with optical-to-electrical conversions. The proposed synchronization technology combined with a flicker and denoising algorithm has given good results and can be applied in high-definition serial data interface (HD-SDI), ultra-HD-SDI, and HD multimedia interface transmission system applications.