• 제목/요약/키워드: optical losses

검색결과 153건 처리시간 0.029초

Scattering characteristics of metal and dielectric optical nano-antennas

  • Ee, Ho-Seok;Lee, Eun-Khwang;Song, Jung-Hwan;Kim, Jinhyung;Seo, Min-Kyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.76.1-76.1
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    • 2015
  • Optical resonances of metallic or dielectric nanoantennas enable to effectively convert free-propagating electromagnetic waves to localized electromagnetic fields and vice versa. Plasmonic resonances of metal nanoantennas extremely modify the local density of optical states beyond the optical diffraction limit and thus facilitate highly-efficient light-emitting, nonlinear signal conversion, photovoltaics, and optical trapping. The leaky-mode resonances, or termed Mie resonances, allow dielectric nanoantennas to have a compact size even less than the wavelength scale. The dielectric nanoantennas exhibiting low optical losses and supporting both electric and magnetic resonances provide an alternative to their metallic counterparts. To extend the utility of metal and dielectric nanoantennas in further applications, e.g. metasurfaces and metamaterials, it is required to understand and engineer their scattering characteristics. At first, we characterize resonant plasmonic antenna radiations of a single-crystalline Ag nanowire over a wide spectral range from visible to near infrared regions. Dark-field optical microscope and direct far-field scanning measurements successfully identify the FP resonances and mode matching conditions of the antenna radiation, and reveal the mutual relation between the SPP dispersion and the far-field antenna radiation. Secondly, we perform a systematical study on resonant scattering properties of high-refractive-index dielectric nanoantennas. In this research, we examined Si nanoblock and electron-beam induced deposition (EBID) carbonaceous nanorod structures. Scattering spectra of the transverse-electric (TE) and transverse-magnetic (TM) leaky-mode resonances are measured by dark-field microscope spectroscopy. The leaky-mode resonances result a large scattering cross section approaching the theoretical single-channel scattering limit, and their wide tuning ranges enable vivid structural color generation over the full visible spectrum range from blue to green, yellow, and red. In particular, the lowest-order TM01 mode overcomes the diffraction limit. The finite-difference time-domain method and modal dispersion model successfully reproduce the experimental results.

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Design and Implementation of Optical Signal Processor in Fiber-Optic Current Transducer for Electric Equipments (전력기기용 고안정성 광섬유 CT 센서의 광 신호처리기 설계 및 구현)

  • Jang, Nam-Young;Choi, Pyung-Suk;Eun, Jae-Jeong;Cheong, Hyeon-Seong
    • Journal of the Institute of Convergence Signal Processing
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    • 제8권3호
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    • pp.171-177
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    • 2007
  • In this paper, we have designed and implemented an optical signal processor in order to use in a fiber-optic current CT for electric equipments where its properties were discussed. The fabricated optical signal processor is used to reduce a measurement current error that induced by the effects of intensity variation in the optical output signal due to losses coming from optical components or polarization variation in a PFOCS. Also, the optical signal processor was fabricated in compact/lightweight with unification of opto-electronic transducer part, analog signal process part, and real-time measurement part consisted of a level shift and ${\mu}-processor$. The experiment of optical signal processor has been performed in the range of $0{\sim}7,500A$ using the PFOCS made all fiber-optic components. As a result of experiment, the linearity error of measurement current is less than 1.7% and its average error is less than 0.3% in the range of $1,000A{\sim}7,000A$.

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Nonhermetic Plastic Packaged Optical Modules of Passive Optical Fiber Alignment Method (수동 광섬유정렬을 이용한 Nohermetic 플라스틱 패키지 광모듈)

  • Lim, Dong-Cheol;Lee, Won-Jong;Kang, Suk-Youb;Park, Hyo-Dal
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제31권11A호
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    • pp.1053-1058
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    • 2006
  • In this paper, We proposed a efficient OSA(Optical Sub-Assembly) packaging method in use 1.31/1.49um bi-directional hybrid-integrated PLC chip for low-cost OSA in optical access network system applications as GE-PON in FTTH. Fabricated OSA with passive optical fiber alignment and nonhermetic plastic package method and measured optical coupling efficiency and electric-optical characteristics. Its performance is feasible to satisfy the GE-PON ONU specifications with the results as less than 0.5dB coupling losses within 40um alignment of z-axis and less than -24dBm sensitivity. It also has good temperature characteristics to sustain optical output power more than 1.5mW and 10dB extinction ratio, less than 0.3dB tracking error.

A Study on WDM Multihop Network Modeling with Optical Component Losses (광소자에서의 손실을 고려한 WDM 다중홉 망설계에 관한 연구)

  • Song, Jae-Yeon;Kim, Jang-Bok
    • The Transactions of the Korea Information Processing Society
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    • 제7권8S호
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    • pp.2729-2734
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    • 2000
  • 본 논문에서는 기존의 논문들이 이상적인 소자들을 가정한 데 비해 WDM 망에서 사용되는 광소자들의 손실특성을 분석하여 수식화하고 이를 이용하여 광경로 설정을 하였다. 비어있는 파장이 있을 경우, 이들 후보 경로중에서 일정 기준 SNR을 만족하면서 최적인 경로를 선택하였다. 그 결과, 파장변환기의 입출력 파장간격에 따라 호거절확률에 변화가 있음을 확인했으며 보다 실제적인 망설계의 방법을 제시하였다.

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Design of an optical add-drop multiplexer (광결합 분기 다중화기의 설계)

  • 이성은;윤지욱;김광준;이종현
    • Proceedings of the IEEK Conference
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    • 대한전자공학회 1999년도 추계종합학술대회 논문집
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    • pp.313-315
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    • 1999
  • We present a 64-channel wavelength multiplexing architecture consisting of two 32-channel wavelength muitiplexers. Measured insertion losses of the 32-channel muitiplexers were below 8㏈ with uniformity in loss among channels better than 1㏈. The architecture of an OADM is also presented which employs FBGs. It is shown that the OADM can add or drop up to 12 channels.

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OFDM Star Network Based on Carrier Distribution (캐리어 분배에 의한 OFDM 스타망에 관한 고찰)

  • 채창준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제21권1호
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    • pp.281-290
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    • 1996
  • In this paper we suggest an OFDM star network based on carrier distribution and homodyne detection in which all optical carriers generated and stabilized in a specific node are distributed to each node. We studied ASK and PSK modulation schemes and calculated rspective SNRs and BERs for this network. We also discussed on the optical power requirement on the light sources for 200 Mb/s transmission speed. As a result, we found tht ASK and PSK respectively require 13 dBm and 10 dBm for 32 nodes and the nmber of nodes can be expanded to 73 with only 0 dBm of power and minimum insertion losses of components. The proposed network is more reliable than the conventional ones due to the centralized carrier maintenance andthe network is suitable for the adverse environment of the nodes.

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Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency

  • Yuan, Qing-Qing;Xia, Kun
    • Journal of Electrical Engineering and Technology
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    • 제10권1호
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    • pp.280-287
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    • 2015
  • Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $i_d$ and $i_q$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $i_d$ and $i_q$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.

Optimal Position of Optical Phase Conjugator for Compensation of Distorted WDM Signals with Initial Frequency Chirp

  • Lee Seong-Real;Choi Byung-Ha;Chung Myung-Rae
    • Journal of electromagnetic engineering and science
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    • 제5권1호
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    • pp.36-42
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    • 2005
  • In this paper, the optimal position of optical phase conjugator(OPC) excellently compensating distorted WDM channels with initial frequency chirp due to both chromatic dispersion and self phase modulation(SPM) is numerically investigated. Highly-nonlinear dispersion shifted fiber(HNL-DSF) is used as a nonlinear medium of OPC in order to widely compensate WDM signal band. It is confirmed that if the OPC position was shifted from mid-way of total transmission length dependence on the initial frequency chirp as well as modulation format and fiber dispersion coefficient, it is possible to cancel the performance degradation owing to the initial frequency chirp. Using proposed configuration, it is possible to remove all in-line dispersion compensator, reducing span losses and system costs in the long-haul broadband WDM systems.

Preparation and Properties of Plastic Optical Fibers (플라스틱 광섬유의 제조 및 특성에 관한 연구)

  • 김한도
    • Textile Coloration and Finishing
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    • 제5권1호
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    • pp.19-25
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    • 1993
  • Plastic optical fibers(POFs) composed of poly(methylmethacrylate) (PMMA), polystyrene (PS), or polycarbonate(PC) as a core materials, and of fluorinated polymer or PMMA as a cladding were fabricated and their properties were investigated in this study. The attenuation loss of PMAA core POF was about 1,700 dB/Km at 660 nm, the loss of PS core POF was 1,800 dB/Km at 560 nm, and the loss of PC core POF was 2,200 dB/Km at 780 nm. These attenuation losses of POFs prepared ill this study were higher than those of commerically available POFs. Compared to PMMA and PS core POFs, PC core POF has excellent characteristics, including high thermal stability, high flexibility, and high impact strength.

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LED Light Coupler Design for a Very Thin Light Guide (초경박 도광판을 위한 LED 광-접합기 설계)

  • Lee, Jun-Ho;Jang, Won-Seok;Yu, Yeong-Eun
    • Proceedings of the Optical Society of Korea Conference
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    • 한국광학회 2007년도 하계학술발표회 논문집
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    • pp.15-16
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    • 2007
  • A design of a light coupler between a LED and a very thin light guide (0.2mm thickness) is presented. Due to the light guide's very thin thickness, conventional light couplings between LEDs and light guides do not provide enough coupling efficiency. We investigate two different coupling methods: side coupling using a complex-shaped lens and bottom coupling using a grating. This paper presents a draft design of the first approach which couples light from 0.4mm LED to 0.2mm light guide without significant losses.

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