• Title/Summary/Keyword: channel waveguide

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Polymer Waveguide Apodized Grating for Narrow-Bandwidth High-Reflectivity Wavelength Filters (협대역 고반사 파장 필터 구현을 위한 폴리머 광도파로 에포다이즈드 격자)

  • Lee, Won-Jun;Huang, Guanghao;Shin, Jin-Soo;Oh, Min-Cheol
    • Korean Journal of Optics and Photonics
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    • v.26 no.4
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    • pp.203-208
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    • 2015
  • Wavelength filters are essential components for selecting a certain wavelength channel of a WDM optical communication system. To realize wavelength filters with narrow bandwidth and high reflectivity, an apodized grating structure with length of 15 mm and index modulation of $5{\times}10^{-4}$ was designed. The device exhibited a reflectivity of 95%, 3-dB bandwidth of 0.28 nm, and 20-dB bandwidth of 0.70 nm on an 18 mm grating length.

Development of Double Rotation C-Scanning System and Program for Under-Sodium Viewing of Sodium-Cooled Fast Reactor (소듐냉각고속로 소듐 내부 가시화를 위한 이중회전구동 C-스캔 시스템 및 프로그램 개발)

  • Joo, Young-Sang;Bae, Jin-Ho;Park, Chang-Gyu;Lee, Jae-Han;Kim, Jong-Bum
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.4
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    • pp.338-344
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    • 2010
  • A double rotation C-scanning system and a software program Under-Sodium MultiVIEW have been developed for the under-sodium viewing of a reactor core and in-vessel structures of a sodium-cooled fast reactor KALIMER-600. Double rotation C-scanning system has been designed and manufactured by the reproduction of double rotation plug of a reactor head in KALIMER-600. Hardware system which consists of a double rotating scanner, ultrasonic waveguide sensors, a high power ultrasonic pulser-receiver, a scanner driving module and a multi channel A/D board have been constructed. The functions of scanner control, image mapping and signal processing of Under-Sodium MultiVIEW program have been implemented by using a LabVIEW graphical programming language. The performance of Under-Sodium MultiVIEW program was verified by a double rotation C-scanning test in water.

50-GHz AWG Interrogation of a Multiple-FBG Temperature Sensor (50-GHz AWG를 이용한 다중 광섬유격자 브래그 파장 계측)

  • Moon, HyungMyung;Kwak, SeungChan;Kim, JinBong;Yim, Ju-Wan;Park, Dong-Young;Im, Kiegon
    • Korean Journal of Optics and Photonics
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    • v.30 no.6
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    • pp.226-229
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    • 2019
  • We investigated an interrogation system for fiber Bragg gratings by using a 50-GHz 96-channel array waveguide grating. Linearity of the sensitivity (the wavelength shift in response to the change in strain or temperature) is achieved for a Bragg grating of sufficiently wide bandwidth. The present wavelength-monitoring system could measure the change in Bragg wavelength with a resolution of 0.01 nm, at intervals of 10 seconds. When this interrogation system was used for a linear array of 12 acrylaterecoated fiber gratings, the wavelength sensitivity changed from 0.018 nm/℃ to 0.01 nm/℃ when the operating temperature changed from -25℃ to 85℃.

Cost Effective Silica-Based 100 G DP-QPSK Coherent Receiver

  • Lee, Seo-Young;Han, Young-Tak;Kim, Jong-Hoi;Joung, Hyun-Do;Choe, Joong-Seon;Youn, Chun-Ju;Ko, Young-Ho;Kwon, Yong-Hwan
    • ETRI Journal
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    • v.38 no.5
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    • pp.981-987
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    • 2016
  • We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two $90^{\circ}$ optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of $2%-{\Delta}$. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a low-cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of $8.3{\times}10^{-11}$ is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing.

Design of 77 GHz Automotive Radar System (77 GHz 차량용 레이더 시스템 설계)

  • Nam, Hyeong-Ki;Kang, Hyun-Sang;Song, Ui-Jong;Cui, Chenglin;Kim, Seong-Kyun;Nam, Sang-Wook;Kim, Byung-Sung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.9
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    • pp.936-943
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    • 2013
  • This work presents the design and measured results of the single channel automotive radar system for 76.5~77 GHz long range FMCW radar applications. The transmitter uses a commercial GaAs monolithic microwave integrated circuit(MMIC) and the receiver uses the down converter designed using 65 nm CMOS process. The output power of the transmitter is 10 dBm. The down converter chip can operate at low LO power as -8 dBm which is easily supplied from the transmitter output using a coupled line coupler. All MMICs are mounted on an aluminum jig which embeds the WR-10 waveguide. A microstrip to waveguide transition is designed to feed the embedded waveguide and finally high gain horn antennas. The overall size of the fabricated radar system is $80mm{\times}61mm{\times}21mm$. The radar system achieved an output power of 10 dBm, phase noise of -94 dBc/Hz at 1 MHz offset and a conversion gain of 12 dB.

Performance of CWDM Fabricated by the PLC-AWG Technology (평판형 AWG 기술을 이용한 광대역 파장다중화/역다중화 소자의 제작 및 특성)

  • Moon, H.M.;Kwak, S.C.;Hong, J.Y.;Lee, K.H.;Kim, D.H.;Kim, J.J.;Choi, S.Y.;Lee, J.G.;Lee, J.H.;Lim, K.G.;Kim, J.B.
    • Korean Journal of Optics and Photonics
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    • v.18 no.3
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    • pp.185-189
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    • 2007
  • A novel technology for CWDM (Coarse Wavelength Division Multiplexer) utilizing a PLC (Planar Lightwave Circuit)-AWG (Arrayed Waveguide Grating) fabrication process is proposed. BPM (Beam Propagation Method) Simulation results on the employed parabolic-horn-type input slab waveguide of AWG and the performance of the 20 nm-channel spacing CWDM with flattened passband are presented. Waveguides of $0.75{\triangle}%$ have been used in this experiment and the insertion loss at the peak wavelength is 3.5 dB for a Gaussian spectrum and is 4.8 dB for a flat-top spectrum. The bandwidth at 3 dB is better than 10 nm and 13 nm for Gaussian and flat-top spectra, respectively.

Performance Analysis of Underwater Acoustic Communication Systems Using Underwater Channel Simulation Tool (수중채널 시뮬레이터를 활용한 수중음향통신 시스템 성능 분석)

  • Oh, Se-Hyun;Kim, Hyeon-Su;Kim, J.S.;Cho, Jung-Hong;Chung, Jae-Hak;Song, H.C.
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.6
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    • pp.373-383
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    • 2012
  • The performance of underwater acoustic communication system is sensitive to the Doppler shift and ISI(Inter-Symbol Interference). Therefore, the simulation algorithm needs to consider time-spread due to multipath arrivals which cause the ISI, and time-varying Doppler shift along with moving source and receiver. For this purpose, VirTEX(Virtual Time series EXperiment) based on Ray model has been developed. In this paper, VirTEX is used to compare the characteristics of ocean waveguide from the experimental data and illustrate the performance. The CIR(Channel Impulse Response) that characterizes the multipath arrivals with representative time-spread due to multipath arrivals is compared between numerically simulated and experimental probe signal. Also, the communication performance analysis for BER(Bit Error Rate) is compared between numerically simulated and experimental data signal. As a result, VirTEX can be useful as a simulation tool for evaluating the performance of underwater acoustic communication system.

Monostatic RCS Reduction by Gap-Fill with Epoxy/MWCNT in Groove Pattern

  • Choi, Won-Ho;Jang, Hong-Kyu;Shin, Jae-Hwan;Song, Tae-Hoon;Kim, Jin-Kyu;Kim, Chun-Gon
    • Journal of electromagnetic engineering and science
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    • v.12 no.1
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    • pp.101-106
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    • 2012
  • In this study, we investigated the effect of groove pattern and gap-fill with lossy materials at 15 GHz frequency of Ku-band. We used Epoxy/MWCNT composite materials as gap-fill materials. Although epoxy does not have an absorbance capability, epoxy added conductive fillers, which are multi-walled carbon nanotubes (MWCNT), can function as radar absorbing material. Specimens were fabricated with different MWCNT mass fractions (0, 0.5, 1.0, 2.0 wt%) and their permittivity in the Ku-band was measured using the waveguide technique. We investigated the effect of gap-fill on monostatic RCS by calculating RCS with and without gap-fill. For arbitrarily chosen thickness and experimentally obtained relative permittivity, we chose the relative permittivity of MWCNT at 2 wt% (${\varepsilon}_r$=8.8-j2.4), which was the lowest reflection coefficient for given thickness of 3.3 mm at V-pol. and $80^{\circ}$ incident angle. We also checked the monostatic RCS and the field intensity inside the groove channel. In the case of H-pol, gap-fill was not affected by the monostatic RCS and magnitude was similar with or without gap-fill. However, in the case of V-pol, gap-fill effectively reduced the monostatic RCS. The field intensity inside the groove channel reveals that different RCS behaviors depend on the wave polarizations.

A Study on Ka band Qualification Model Multiplexers for Communication, Ocean and Meteorological Satellite (COMS) Payload (통신해양기상위성 Ka 대역 인증모델 밀티플렉서에 대한 연구)

  • Eom, Man-Seok;An, Gi-Beom;Yun, So-Hyeon;Gwak, Chang-Su;Yeom, In-Bok
    • Journal of Satellite, Information and Communications
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    • v.1 no.2
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    • pp.63-70
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    • 2006
  • This paper presents the results of Ka band qualification model multiplexers for COMS Payload to be launched in 2008. These are the input and output multiplexers of the satellite transponder to use available frequency resources effectively and the diplexer of the satellite antenna to use the same reflector for both transmitting and receiving frequency bands, respectively. The input multiplexer with four frequency channels has four(4) independent channel filters which consist of an 8-pole elliptic band-pass filter for high frequency selectivity and a 2-pole equalizer for group delay equalization. For low insertion loss, mass and volume reduction, manifold type os employed for output multiplexer. E-plane T-junction is used for either splitting or combining a frequency band into two sub-bands. Asymmetric inductive irises are used to tune the receiving filter easily. The electrical performance and environmental test such as vibration test, mechanical shock test, thermal vacuum test and EMC test are performed and the results of all qualification model multiplexers are compliant to the requirement of each multiplexer. Followed by this qualification, the flight model equipment will be developed.

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Design of K-Band Radar Transceiver for Tracking High Speed Targets (고속 표적 추적을 위한 K-대역 레이다 송수신기 설계)

  • Sun, Sun-Gu;Lee, Jung-Soo;Cho, Byung-Lae;Lee, Jong-Min
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.11
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    • pp.1304-1310
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    • 2010
  • This study is to design FMCW radar transceiver of K-band which is used to detect and track approaching high speed targets with low altitude. The transmitter needs high output power due to small RCS targets and wide beamwidth of transmit antenna. Multi-channel receivers are required to detect and track targets by interferometer method. Transmitter consists of high power amplifier, waveguide switch, and frequency up-converter. Receiver is composed of five channel receivers, up and down converters, X-band local oscillator and waveform generator. Before manufacturing it, the proposed architecture of transceiver is proved by modeling and simulation using several parameters. Then, it is manufactured by using industrial RF components. The performance parameters are measured through experiment. In the experiment, transmitting power and receiver gain were measured with 39.64 dBm and 29.1 dB, respectively. All other parameters in the specification were satisfied as well.