• Title/Summary/Keyword: Optical propagation

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A new WDM/TDM protocol for very high speed optical networks (고속광통신망용 새로운 WDM/TDM 프로토콜)

  • 이상록;이성근;박진우
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.2
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    • pp.50-58
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    • 1996
  • This paper proposes the channel-access protocol suitable to a very high speed photonic WDM network with star configuration, which can provide a high channel utilization and insensitivity to the propagation delay. The proposed protocol employs a control channel and a simple status table to deal with the propagation delay which has been a major limiting factor in the performance of the very high speed optical communication networks. The control channel transmits control information in order to reserve access on data channels, and each node constitutes a status table after the reception of control pckets which holds information about the availbility of destination node and data channel. The proposed protocol is insensitive to the propagation delay time by removing necessity of the retransmission and by allowing parallel transmission of control packet and data packets. It is proved in analysis and discrete event simulation that the proposed protocol is superior in throughput and mean delay, especially at the high load conditions compared to the existing high speed channel-access protocols.

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Propagation Properties of a Partially Coherent Flat-Topped Vortex Hollow Beam in Turbulent Atmosphere

  • Liu, Dajun;Wang, Yaochuan;Wang, Guiqiu;Yin, Hongming
    • Journal of the Optical Society of Korea
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    • v.20 no.1
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    • pp.1-7
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    • 2016
  • Using coherence theory, the partially coherent flat-topped vortex hollow beam is introduced. The analytical equation for propagation of a partially coherent flat-topped vortex hollow beam in turbulent atmosphere is derived, using the extended Huygens-Fresnel diffraction integral formula. The influence of coherence length, beam order N, topological charge M, and structure constant of the turbulent atmosphere on the average intensity of this beam propagating in turbulent atmosphere are analyzed using numerical examples.

Characteristics of THz Pulse Propagation on Teflon Covered Two-Wire Lines

  • Jo, Jeong Sang;Jeon, Tae-In
    • Journal of the Optical Society of Korea
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    • v.19 no.6
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    • pp.560-565
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    • 2015
  • We report efficient direct coupling of THz dipole antenna pulses onto air spaced two-wire transmission lines and Teflon covered two-wire lines. The air spaced two-wire lines show TEM mode propagation with very small group velocity dispersion (GVD) and relatively low attenuation. The Teflon covered two-wire lines showed comparatively much higher attenuation and GVD. However, the Teflon covered two-wire lines show a very good guiding property when the lines are curved. Although the lines are circled only 5.0 cm in diameter, there is no additional attenuation compared to straight the lines.

Perspectives on THz Time Domain Spectroscopy

  • Cheville, R.Alan
    • Journal of the Optical Society of Korea
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    • v.8 no.1
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    • pp.34-52
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    • 2004
  • Over the past decade the experimental technique of THz time domain spectroscopy (㎔- TDS) has proved to be a versatile method for investigating a wide range of phenomena in the ㎔ or far infrared spectral region from 100 ㎓ to 5 ㎔. This paper reviews some recent results of the Ultrafast ㎔ Research Group at Oklahoma State University using ㎔-TDS as a characterization tool. The experimental technique is described along with recent results on ㎔ beam propagation and how ㎔ beam profiles arise from propagation of pulse fronts along caustics. To illustrate how spatio-temporal electric field measurements can determine material properties over a wide spectral range, propagation of ㎔ pulses through systems exhibiting frustrated total internal reflection (FTIR) are reviewed. Finally two potential metrology applications of ㎔-TDS are discussed, thin film characterization and non-destructive evaluation of ceramics. Although ㎔-TDS has been confined to the research laboratory, the focus on application may stimulate the adoption of ㎔- TDS for industrial or metrology applications.

Focal Plane Irradiance from MCF in Millimeter Wave Systems

  • Jong Gil Lee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.3
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    • pp.529-534
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    • 2004
  • Millimeter waves are potentially useful for high resolution ranging and imaging in low optical visibility conditions such as fog and smoke. Also, They are used for wide band communications. However, it is necessary to develop a theoretical and experimental understanding of millimeter wave propagation to assess the performance of millimeter wave systems. The intensity fluctuations and mutual coherence function (MCF) describe atmospheric effects on the millimeter wave propagation. Using the quasi-optical method (QOM), an efficient and practical method was suggested to obtain the intensity distribution of the antenna focal plane from MCF which can be determined using meteorological data.

Analysis of Arrayed Waveguide Grating Waveglength Filter using Wide Angle Beam Propagation Method (Wide Angle BPM 을 이용한 광도파로열 격자 파장 필터의 해석)

  • Park, Jun-O;Jeong, Yeong-Cheol
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.39 no.2
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    • pp.46-55
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    • 2002
  • The key component to accomplish the WDM all optical network is an Arrayed Waveguide Grating(AWG) wavelength filter Numerical analysis is necessary for design and analysis of optical components like AWG wavelength filter. Beam Propagation Method(BPM) is the most widely-used method. In this paper, we analyze the difference between the paraxial BPM and the WA-BPM when they are applied to the analysis of InP/InGaAsP/InP AWG wavelength filter. The paraxial BPM is based on paraxial approximation, and the WA-BPM is based on the low order Pade approximant. The side lobe level(SLL) and insertion loss calculated from both methods are compared. The high order Pade approximant will to used to more accurate design and analysis of AWG.

Effects of Drying Temperature on the Optical Properties of Solution Derived (Pb, La)$TiO_3$ Thin Films

  • Yoon, Dae-Sung;Kim, Sung-Wuk;Koo, Jun-Mo;Jiang, Zhong-Tao
    • The Korean Journal of Ceramics
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    • v.1 no.4
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    • pp.191-196
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    • 1995
  • Using sol-gel processing method, thin films of lathanum modified lead titanate(PLT) on Corning 7059 glass were prepared. A differential thermal analysis (DTA/TG) curve of gel powder and infrared spectra (FT-IR) of the films were measured to estimate residual organices in them. The heat-treated films were characterized by X-ray diffraction(XRD). Microstructures of the films were observed by a scanning electron microscope (SEM). Optical properties of the films were determined by a UV-VIS spectrophotometer. The waveguiding properties and optical attenuation were measured with the end coupling method and the cut back method. Effects of the drying conditions on the transmittance and the propagation loss of the films were investigated. Experimemtal results showed that the content of residual organics in the film decreased as the drying temperature of the film increased. As the La content of the film increased, the grain size decreased and the transmittance increased. The transmittances of the films increased with the increasing of the drying temperature. The propagation losses in the film decreased as the drying temperature increased.

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The Analysis of tight Coupling and Propagation for a Composite Fiber-Dielectric Slab with a Conductor Cladding

  • Kwon, Kwang-Hee;Song, Jae-Won;Kim, Jeong-Hoon;Park, Euy-Don;Son, Seok-Woo
    • Journal of the Optical Society of Korea
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    • v.7 no.1
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    • pp.20-27
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    • 2003
  • A theoretical presentation of evanescent coupling is offered with respect to the refractive indexes between a side-polished optical fiber and an infinitely planar waveguide with a conductor cladding (PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with the perfect conductor (PEC) on one side. The behavior of the distributed couple. is examined using a coupled mode model, which takes account of the two dimensions of the waveguide configuration. The coupling and propagation of light were found to depend on both the relationship between the refractive index values of each structure and the configuration of the side-polished fiber used in the PWGCC. The spreading of light in the unconfined direction of the PWGCC is described in terms of a simple geometrical interpretation of the synchronization condition that is in agreement with a previous investigation of the problem based on the coupled-mode theory (CMT). The power of the light propagation in the fiber decreased exponentially along the fiber axis as it was transferred to the PWGCC, where it was carried away.

Sensitivity and Error Propagation Factors for Three-Parameter Ellipsometry

  • Ihm, Hye-Ran;Chung, Gyu-Sung;Paik, Woon-Kie;Lee, Duck-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.15 no.11
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    • pp.976-980
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    • 1994
  • The sensitivity factors and the error propagation factors are defined for the three-parameter ellipsometry (TPE). The sensitivity factor is useful for understanding the nature of the TPE measurements in connection with determination of the optical properties and the thickness of a film. On the other hand, the error propagation factors provide a quantitative tool for predicting the optimum condition for TPE experiments. Their usefulness is demonstrated for the passive film formed on nickel in aqueous solution.

Effect of a Conductor Cladding on a Dielectric Slab for Coupling with a Side-polished Fiber

  • Kwon, Kwang-Hee;Song, Jae-Won
    • Journal of the Optical Society of Korea
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    • v.7 no.3
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    • pp.180-187
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    • 2003
  • A theoretical presentation by using a three-dimensional finite difference beam propagating method (3-D FD-BPM) for the evanescent coupling is offered with respect to the refractive indexes between a side-polished optical fiber and an infinitely planar waveguide with a conductor cladding (PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with a perfect conductor (PEC) on one side. The coupling and propagation of light are found to depend on both the relationship between the refractive index values of two structures and the configuration of the side-polished fiber used in the PWGCC. The spreading of light in the unconfined direction of a PWGCC is presented with the distribution of electric fields in xy - plane and the absolute amplitude of electric fields along the x and y axis. The power of the light propagation in a fiber decreases exponentially along the fiber axis as it is transferred to the PWGCC, where it is carried away.