• Title/Summary/Keyword: channel waveguide

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Nano-structuring of Transparent Materials by Femtosecond Laser Pulses

  • Sohn, Ik-Bu;Lee, Man-Seop;Chung, Jung-Yong;Cho, Sung-Hak
    • Journal of the Optical Society of Korea
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    • v.9 no.1
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    • pp.1-5
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    • 2005
  • Using tightly focused femtosecond laser pulses, we produce an optical waveguide and optical devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three-dimensional optical devices. In this paper, an optical splitter and U-grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near-IR femtosecond laser pulses. The fiber aligned optical splitter has a low insertion loss, less than 4㏈, including an intrinsic splitting loss of 3㏈ and excess loss due to the passive alignment of a single-mode fiber. Finally, we demonstrate the utility of the femtosecond laser writing technique by fabricating gratings at the surface and inside the silica glass.

Fabrication of Planar Lightwave Circuits for Optical Transceiver Connection using Glass Integrated Optics (광 송수신기 연결을 위한 유리집적광학 평면 광 회로 제작)

  • Gang, Dong-Seong;Jeon, Geum-Su;Kim, Hui-Ju;Ban, Jae-Gyeong
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.6
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    • pp.412-419
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    • 2001
  • In accordance with the PON(passive optical network) could be setup, effective connections with light sources, optical detectors, and optical fibers are the best sensitive points to represent the efficiency of network. Therefore, in this paper we designed and fabricated optical transceiver connection chip that was consisted of channel waveguide, Y-branch, and CWDM on the 2" BK7 glass substrate. This chip can be used for 1.31/1.55${\mu}{\textrm}{m}$ CWDM network and 1.55${\mu}{\textrm}{m}$ region dense WDM network.work.

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DWDM Channel Level Controller Design and Implementation (DWDM 채널 레벨 컨트롤러 설계 및 구현)

  • 염진수;이규정;허창우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.655-657
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    • 2004
  • 채널 레벨 컨트롤러는 DWDM(Dense Wavelength Division Multiplexing) 방식의 OXC(Optical Cross Connect), OADM(Optical Add/Drop Multiplexer), 광 증폭기(EDFA : Erbium Doped Fiber Amplifier) 둥의 시스템에서 채널별 광신호의 세기를 조절하여 시스템의 신뢰성을 높이는 중요한 제어기다. 본 논문에서는 12채널 VOA(Variable Optical Attenuator) 4개를 사용하여 40채널의 광 신호 레벨을 제어할 수 있는 컨트롤러를 구현하였다. 각 채널의 광 신호 레벨을 제어하는데 하나의 마이크로 프로세서가 5개의 채널을 제어하고 총 8개의 마이크로프로세서로 40채널을 분산 제어하도록 구성하였다. 또한 외부와 통신을 하고 사용자로부터의 명령을 각각의 마이크로프로세서에 전달하기 위한 마이크로프로세서를 추가하였으며, 출력되는 광 신호의 세기를 측정하여 VOA를 제어하는데 있어서 VOA 출력에서 바로 PD(Photo Detector)로 입력하여 AWC(Arrayed Waveguide Grating) 출력에서 광 신호를 다시 분파하여 PD에 입력하는 번거로움을 개선하였다.

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Analysis of Dielectric Rectangular Waveguide and Directional Coupler with Step Index Profile by the Modified Effective Index Method (수정된 실효 굴절율법에 의한 계단형 굴절률 분포를 갖는 광도파로와 방향성 결합기의 해석)

  • Kim, Chang Min;Jung, Byung Gi;Lee, Choang Woong
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.23 no.4
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    • pp.522-528
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    • 1986
  • Based on the modified effective index method, analysis of dielectric rectangular waveguides and directional couplers are presented. Aside from the effective index concept of channel region, the equivalent index concept of cladding region is proposed. The error problem of eigenvalues, which has been experienced when the effective index method is used, is improved. Our approxiamtions give similar accuracy when compared with the results of other regorous approxiamtion techiniques. The advantage of the modified effective index methods is utilized by replacing the directional coupler with the equivalent slab guides, and the coupling constant is calculated by the coupled mode theory. The effectiveness of the equivalent index concept is positively confirmed.

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Design and Fabrication of the Ka-Band Receive Module for Millimeter Wave Seeker (밀리미터파 탐색기를 위한 Ka-대역 수신기 모듈의 설계 및 제작)

  • Yang, Seong-Sik;Lim, Ju-Hyun;Song, Sung-Chan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.1
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    • pp.78-84
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    • 2012
  • In this paper, we introduced the design technique about a Ka band receive module for millimeter wave seekers. The receiver module consists of a waveguide, circulator and transition for antenna connection, and a limiter and gain control amplifier for receiver protection. This module is comprised of a sum, azimuth and elevation channel for receiving monopules signal, and a SLB channel for the acquisition of jamming signal. In this paper, receiver gain and range of gain control dependent on ADC nonlinear characteristic was analyzed and designed for wide dynamic range receive. In the test result of the fabricated Ka-band receive, the frequency band is 1 GHz, the noise figure is as low as 8.2 dB, the gain is $56{\pm}2dB$, the dynamic range is 135 dB, the gain congtrol is more than 86 dB, the channel isolation is more than 35 dB.

Design Optimization for Air Ducts and Fluid Pipes at Electromagnetic Pulse(EMP) Shield in Highly Secured Facilities (EMP 방호시설의 덕트 및 배관 최적 설계 방안)

  • Pang, Seung-Ki;Kim, Jae-Hoon
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.10 no.4
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    • pp.15-24
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    • 2014
  • This study conducted a computational fluid dynamics(CFD) analysis to find an appropriate diameter or sectional area of air ducts and fluid pipes which have an electromagnetic pulse(EMP) shied to protect indoor electronic devices in special buildings like military fortifications. The result shows that the optimized outdoor air intake size can be defined with either the ratio of the maximum air velocity in the supply duct to the air intake size, or the shape ratio of indoor supply diffuser to the outdoor air intake. In the case of water channel, the fluid velocity at EMP shield with the identical size of the pipe, decreases by 25% in average due to the resistance of the shield. The enlargement of diameter at the shield, 2 step, improves the fluid flow. It illustrated that the diameter of downstream pipe size is 1step larger than the upstream for providing the design flow rate. The shield increases friction and resistance, in the case of oil pipe, so the average flow velocity at the middle of the shield increase by 50% in average. In consideration of the fluid viscosity, the oil pipe should be enlarged 4 or 5 step from the typical design configuration. Therefore, the fluid channel size for air, water, and oil, should be reconsidered by the engineering approach when EMP shield is placed in the middle of channel.

WDM/TDM-Based Channel Allocation Methodology in Optical Network-on-Chip (광학 네트워크-온-칩에서 WDM/TDM 기반 채널 할당 기법)

  • Hong, Yu Min;Lee, Jae Hoon;Han, Tae Hee
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.7
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    • pp.40-48
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    • 2015
  • An optical network-on-chip(ONoC) architecture is emerging as a new paradigm for solving on-chip communication bottleneck. Recent studies on ONoC have been focusing on supporting the parallel transmission and avoiding path collisions using wavelength division multiplexing(WDM). However, since the maximum number of wavelengths, which a single waveguide can accommodate is limited by crosstalk and insertion loss. Therefore previous WDM studies based on incrementing the number of different wavelengths according to the number of nodes would be infeasible due to the implementation complexity. To solve such problems, we combined time division multiplexing(TDM) and wavelength-routed ONoC, along with an optimized channel allocation algorithm, which can minimize the number of extra wavelength channels and latency caused by combining TDM scheme.

Method for eliminating source depth ambiguity using channel impulse response patterns (채널 임펄스 응답 패턴을 이용한 음원 깊이 추정 모호성 제거 기법)

  • Cho, Seongil
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.2
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    • pp.210-217
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    • 2022
  • Passive source depth estimation has been studied for decades since the source depth can be used for target classification, target tracking, etc. The purpose of this paper is to solve the problem of ambiguity in the previous paper [S.-il. Cho et al. (in Korean), J. Acoust. Soc. Kr. 38, 120-127 (2019)] that source depth is estimated in two points. The patterns of phase shift of Channel Impulse Response(CIR) reflected in ocean surface and bottom is used for removing ambiguity of the source depth estimation, and after removing ambiguity, source depth is estimated at one point through the intersection of CIR. In order to extract CIR in case of unknown source signal and continuous signal or noise, Ray-based blind deconvolution is used. The proposed algorithm is demonstrated through numerical simulation in ocean waveguide.

Shared-type Encoder/Decoder Based on 2-D Optical Codes for Large Capacity Optical CDMA Network (대용량 광 부호 분할 다중접속(Optical CDMA) 네트워크를 위한 2차원 코드의 공유형 부호기/복호기)

  • Ko Wonseok;Shin Seoyong;Hwang Humor;Chang Chulho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.5A
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    • pp.359-369
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    • 2005
  • For large capacity optical CDMA networks, we propose a shared-type encoder/decoders based on an tunable wavelength converter(TWC) and an arrayed waveguide grating (AWG) router. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

Prediction and Measurement of Propagation Path Loss in Underground Environments (지하공간에서의 전파 경로손실의 예측 및 측정)

  • 김영문;진용옥;강명구
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.4
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    • pp.736-742
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    • 2003
  • This paper presents the propagation path loss in a tunnel which is a kinds of underground environments. To predict propagation path loss more accurately, we choose a straight tunnel with rectangular cross-section. The simulated receiver powers that are using a hybrid waveguide model and a Ray-Tracing method, are compared with the measured ones as a function of distance between TX and RX antennas in tunnel. The attenuation value of regression analysis for measured power in the tunnel is 0.0238dB/m which is similar to the one of the EH1.2 mode, 0.0246dB/m in hybrid waveguide model. By comparing simulation with measurement in tunnels, it has been shown that the measured values are approximate to the simulated results of ray-tracing model. In the analysis of wide-band channel characteristics of the tunnel, the more the distance between TX and RX antennas in tunnel increases, RMS delay spread increases and coherence bandwidth decreases.