• Title/Summary/Keyword: Fiber optics

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Multiwavelength Erbium-doped Fiber Ring Laser with Adjustable Line Power using Variable Attenuators and DWDM

  • Lee, Hojoon
    • Korean Journal of Optics and Photonics
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    • v.25 no.3
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    • pp.146-149
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    • 2014
  • The homogeneous line broadening in EDF leads to unstable lasing and strong mode competition. In this paper a multiwavelength fiber ring laser that overcomes these effects by using variable attenuators between the DWDM and $1{\times}N$ coupler, has been proposed. Fiber ring lasers with four and eight wavelength outputs are implemented, and we show that the output powers can be adjusted with stable operation. The EDF ring laser has one four-wavelength output and four of single wavelengths, with OSNR of 50 and 60 dB respectively.

Controlling the Intensity Distribution of Light at the Output of a Multimode Optical Fiber Using a Polar-coordinate-based Transmission-matrix Method (극좌표 기반 투과 매트릭스 방법을 이용한 다중모드 광섬유 출력단에서의 빛의 세기 분포 제어)

  • Park, Jaedeok;Jo, Jaepil;Yoon, Jonghee;Yeom, Dong-Il
    • Korean Journal of Optics and Photonics
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    • v.33 no.6
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    • pp.252-259
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    • 2022
  • We have conducted a study to control the light-intensity distribution at the output end of a multimode optical fiber via estimating the transmission matrix. A circularly arranged Hadamard eigenmode phase distribution was implemented using a spatial light modulator, and the transmission matrix of a multimode optical fiber was experimentally obtained using a four-phase method. Based on the derived transmission matrix, the spatial phase distribution of light incident upon the optical fiber was adjusted via the spatial light modulator in advance, to focus the light at a desired position at the optical fiber output. The light could be focused with an intensity up to 359.6 times as high as that of the surrounding background signal at a specific position of the multimode fiber's output end, and the intensity of the focused beam was on average 104.6 times as large as that of the background signal, across the area of the multimode fiber's core.

Fiber optic sensor technology for sensing/controlling vibration and deformation of lightweight structures (경량 구조물의 진통 및 변형 감지/제어를 위한 광섬유 센서 기술)

  • Han, Jae-Hung;Kang, Lae-Hyong;Mueller, Uwe C.;Rapp, Stephan;Baier, Horst
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.157-163
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    • 2006
  • Vibration and deformation sensing control of lightweight structures using optical fiber sensor technology is introduced in this presentation. This paper shows several examples of vibration control and deformation estimation for structures using these optical fiber sensor systems. Among various optical fiber sensors, in this paper, two types of optical fiber sensors, Fabry-Perot Interferometer(EFPI) and Fiber Bragg Grating(FBG) sensors, are mainly dealt with. Fiber optic sensors show many advantages over conventional strain gages for the measurement of vibration and deformation of lightweight structures.

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Characterization of an all fiber optic gyroscope constructed with polarization maintaining fiber; (편광유지 광섬유 자이로스코프 제작 및 특성 측정)

  • 전민용
    • Korean Journal of Optics and Photonics
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    • v.4 no.4
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    • pp.487-492
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    • 1993
  • A polarization maintaining fiber optic gyroscope was constructed having an optical loss of about 25 dB. Using the earth rotation rate as a reference, the long term stability of better than $3^{\circ}/hr$ and the rms short term noise of $0.6^{\circ}/hr/{\sqrt{Hz}}$ were obtained.

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Design of a Taper-Underlaid Spot-Size Converter with an Offset

  • Choi, Jun-Seok;Oh, Jin-Kyong;Lee, Dong-Hwan;Lee, Hyung-Jong;Kim, Sang-Duk
    • Journal of the Optical Society of Korea
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    • v.11 no.1
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    • pp.40-43
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    • 2007
  • We propose a taper-underlaid spot-size converter (TU-SSC) with an offset which consists of two vertically stacked taper layers. The designed TU-SSC reduces coupling loss of a high index-contrast waveguide with $1.5%{\Delta}$ to a single mode fiber from 1.5 dB to 0.27 dB. We also considered the effects of mask misalignment in the fabrication process of TU-SSC, and optimized the design of TU-SSC so that the additional loss of TU-SSC for the mask misalignment of $3{\mu}m$ in the photo-lithography process was as low as 0.13 dB.