• Title/Summary/Keyword: Fiber coupler

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Characteristics of A Diaphragm-Type Fiber Optic Fabry-Perot Interferometric Pressure Sensor Using A Dielectric Film (유전체 박막을 이용한 다이아프램형 광섬유 Fabry-Perot 간섭계 압력센서의 특성)

  • Kim, M.G.;Yoo, Y.W.;Kwon, D.H.;Lee, J.H.;Kim, J.S.;Park, J.H.;Chai, Y.Y.;Sohn, B.K.
    • Journal of Sensor Science and Technology
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    • v.7 no.3
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    • pp.147-153
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    • 1998
  • The strain characteristics of a fiber optic Fabry-Perot pressure sensor with high sensitivity using a Si3N4/SiO2/Si3N4 (N/O/N) diaphragm is experimentally investigated. A 600 nm thick N/O/N diaphragm was fabricated by silicon anisotropic etching technology in 44 wt% KOH solution. An interferometric fiber optic pressure sensor has been manufactured by using a fiber optic Fabry-Perot intereferometer and a N/O/N diaphragm. The 2 cm length fiber optic Fabry-Perot interferometers in the continuous length of single mode fiber were produced with two pieces of single mode fiber coated with TiO2 dielectric film utilizing the fusion splicing technique. The one end of the fiber optic Fabry-Perot interferometer was bonded to a N/O/N diaphragm. and the other end was connected to an optical setup through a 3 dB coupler. For the N/O/N diaphragm sized 2×2mm2 and 8×8mm2, the pressure sensitivity was measured 0.11 rad/kPa and 1.57 rad/kPa, respectively, and both of the nonlinearities were less than 0.2% FS.

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Dielectric Thin Film Mirror Embedded Optical Fiber Couplers (유전체 박막 거울 내장형 광섬유 결합기)

  • 신종덕
    • Korean Journal of Optics and Photonics
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    • v.4 no.4
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    • pp.420-427
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    • 1993
  • Dielectric thin film mirrors are embedded in multimode and single-mode fibers by a fusion splicing technique. The fibers with 45 angled embedded mirrors serve as ultra-compact directional couplers with low excess optical loss of 0.2 dB for multimode and 0.5 dB for single mode at 1.3 μm and excellent mechanical properties. The reflectance is wavelength dependent and strongly polarization depencient. Far-field scans of the reflected output power measured with a white-light source show a pattern which is almost circularly symmetric with aspect ratio of 1.09 at 5% of the peak power. The splitting ratio in a multimode coupler measured with a diode laser source is much less dependent on input coupling conditions than in conventional fused biconical-taper couplers, indicating that these couplers are less susceptible to modal noise occuring in optical fiber communication systems. Spectral properties of multilayer internal mirrors normal to the fiber axis have been investigated experimentally, and a matrix analysis has been used to explain the results.

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Investigation of the Lateral Acoustic Signal Detection Using by Two Fabry-Perot Fiber Optic Sensor Array (두 개의 Fabry-Perot 광섬유 센서 배열을 이용한 횡방향 음압 감지 특성 연구)

  • Lee, Jong kil
    • 대한공업교육학회지
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    • v.31 no.1
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    • pp.185-199
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    • 2006
  • In this paper, to detect lateral direction sound pressure fiber optic sensor using Fabry-Perot interferometeric sensor array was fabricated and experimented. This parallel sensor array composed of one light source and the light split into each sensor using directional coupler and to see the output signal the array system do not need any digital signal processor. As a lateral direction sound source arbitrary sound frequency of 100Hz, 200Hz, and 655Hz using by nondirectional speaker were applied to the array sensor which installed on 60cm×60cm×60cm latticed structure. The detected signals from the two sensors were analyzed in the time and frequency domains. It was confirmed that the suggested sensor array detected applied sound source well but there were a little amplitude differences in between the sensors. Because the sensor supported simply at both ends theoretical analysis was performed and its solution was suggested. To compare the theoretical and experimental results arbitrary sound frequency of 2kHz was applied to the sensor array. It shows that experimental results was good agreement with theoretical results.

Performance Analysis and the Novel Optical Decoder Scheme for Optical CDMA System (광 CDMA를 위한 새로운 광복호기 설계와 성능분석)

  • 강태구;윤영설;최영완
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.7C
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    • pp.712-722
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    • 2002
  • We have investigated a novel optical decoder for a fiber-optic code division multiple access(CDMA) communication systems. The conventional optical encoder and decoder have the advantage of simple structure. However the number of users in the system is limited by the auto- and cross-correlation properties generated in decoding process. In previous studies, to improve the system performance, although they used an optical code that minimize the sidelobe and cross-correlation, could not yet find a novel methods for performance improvement in fiber-optic CDMA system. Thus, it is necessary to investigate the novel optical decode in order to improve the performance of system. In this paper, we schematize the AND gate logic element(AGLE) composed with 1×2 or 1×3 coupler and the optical thyristor and propose the novel optical decoder using K(weight) AGLE. The optical thyristor only passes the overlapped signal and clips other signals. Such a novel concept means that the optical thyristor can operate as a hard-limiter. We analyze the fiber-optic CDMA system using the novel optical decoder with simulation and is found that the novel optical decoder using the AGLE and optical thyristor excludes the sidelobe and cross-correlation intensity between any two sequences.

Design and Fabrication of DWDM Multiplexer Using Optical Fiber Biconical Tapered Couplers (광섬유 용융인장 방법에 의한 DWDM용 광다중화기의 제작)

  • Chang, Jin-Hyeon;Kim, Myoung-Saeng;Kang, Duk-Keun
    • Journal of The Institute of Information and Telecommunication Facilities Engineering
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    • v.3 no.2
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    • pp.51-60
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    • 2004
  • In this paper, 8-channel multiplexer with 100GHz channel spacing is fabricated. The 8-channel multiplexer is fabricated by connecting three cascaded Mach Zehnder Interferometer (MZI) of optical fiber type, and each interferometer has the wavelength interval of 100GHz, 200GHz and 400GHz, respectively. furthermore, to acquire uniform insertion loss, it is fabricated by using Wavelength Flatten Coupler (WFC) in which the variation of insertion loss is low. Especially, the variation of wavelength interval in the output is explicitly simulated as a function of optical path difference, and the wavelength coupling process along with cascaded connection is discussed. CO2 laser to adjust precisely the wavelength. In summary, The prototype composed by eight cascaded MZI has an insertion loss of 2.1dB, the bandwidth of 0.8nm at 5.5dB point, and channel crosstalk of 25dB Furthermore, the loss dependent on polarization is measured as 0.06dB.

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Development of Reflection-type Fiber-optic pH Sensor Using Sol-gel Film (졸-겔 필름을 이용한 반사형 광섬유 pH 센서의 개발)

  • Yoo, Wook-Jae;Seo, Jeong-Ki;Jang, Kyoung-Won;Moon, Jin-Soo;Han, Ki-Tek;Park, Jang-Yeon;Lee, Bong-Soo;Cho, Seung-Hyun;Heo, Ji-Yeon;Park, Byung-Gi
    • Journal of Sensor Science and Technology
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    • v.20 no.4
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    • pp.266-271
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    • 2011
  • A reflection-type fiber-optic pH sensor, which is composed of a pH sol-gel film, plastic optical fibers, a mirror, a light source and a spectrometer, is developed in this study. As pH indicators, a bromthymol blue, a cresol red and a thymol blue are used, and they are immobilized in the sol-gel films. The emitted light from a light source is guided by a fiber-optic Y-coupler and plastic optical fibers to the pH sol-gel film in a pH sensing probe. The pH change in the sensing probe gives rise to a change in the color of the pH sol-gel film, and the optical characteristic of reflected light through the pH sol-gel film is also changed. Therefore, we have measured the spectra of reflected lights, which are changed according to the color variations of the pH sol-gel films with different pH values, by using of a spectrometer. Also, the relationships between the pH values and the intensities of reflected lights are obtained on the basis of the color variations of the pH sol-gel films.

Fourier Domain Optical Coherence Tomography for Retinal Imaging with 800-nm Swept Source: Real-time Resampling in k-domain

  • Lee, Sang-Won;Song, Hyun-Woo;Kim, Bong-Kyu;Jung, Moon-Youn;Kim, Seung-Hwan;Cho, Jae-Du;Kim, Chang-Seok
    • Journal of the Optical Society of Korea
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    • v.15 no.3
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    • pp.293-299
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    • 2011
  • In this study, we demonstrated Fourier-domain/swept-source optical coherence tomography (FD/SS-OCT) at a center wavelength of 800 nm for in vivo human retinal imaging. A wavelength-swept source was constructed with a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, isolators, and a fiber coupler in a ring cavity. Our swept source produced a laser output with a tuning range of 42 nm (779 to 821 nm) and an average power of 3.9 mW. The wavelength-swept speed in this configuration with bidirectionality is 2,000 axial scans per second. In addition, we suggested a modified zero-crossing method to achieve equal sample spacing in the wavenumber (k) domain and to increase the image depth range. FD/SS-OCT has a sensitivity of ~89.7 dB and an axial resolution of 10.4 μm in air. When a retinal image with 2,000 A-lines/frame is obtained, an acquisition speed of 2.0 fps is achieved.

A possible application of the partial discharge measurement due to artificial defect using Pockets sensor in GIS(Gas Insulated Switchgear) (가스절연기기(GIS)의 인위적 결함에 의한 부분방전의 검출을 위한 Probe-Type Pockels Sensor의 적용 가능성)

  • Ryu, Cheol-Hwi;Lee, Jae-Ho;Ma, Ji-Hoon;Kang, Won-Jong;Chang, Yong-Moo;Koo, Ja-Yoon
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1770-1772
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    • 2003
  • 본 연구는 국내에서 최초로 제안되고 적용가능성이 입증되어 설계, 제작된 Probe-type Pockets sensor(HY-Pockets Sensor)를 GIS등의 고전압 장비들에 응용한 레이저 부분방전 진단 시스템 개발을 목표로 하고 있다. 이러한 목적으로, 170kV 급 실 규모 GIS내부의 전류 도체에 다양한 곡률 반경의 침 전극을 부착시켜 부분 방전에 기인된 불평등 전계를 형성시켜 개발된 센서의 실규모 적용 가능성을 고찰하였다. 본 레이저 계측 시스템은 He-Ne laser, single multi-mode optical fiber, 2×2 50/50 laser to single mode fiber coupler, probe-type Pockets sensor, photo detector 등으로 구성하여 레이저의 진행을 유도하고, 신호의 특성을 분석하였다. probe-type Pockets sensor로부터 의 출력 신호는 photo detector를 통해 전기적 신호로 변환되어 digital oscilloscope에 의해 측정되고, 또한 PC를 통해 데이터의 저장과 통계적, 분석적 처리 과정을 수행하게 된다. 본 연구의 결과로서 부분방전원에서 생성된 방전 신호에 대한 거리에 따른 센서 감도 결정, 그에 대한 센서 감도의 보정 향상, 전계의 세기의 변화에 따른 센서의 선형성 등이 도출되었고, 이러한 실험결과를 통해 실 GIS(170kv급) 내부에서 발생하는 부분방전의 검출에 본 레이저 부분방전 진단 시스템의 적용 가능성이 제시 되었다.

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A Study on The Motion Charateristic of Ultra Precision Multi-Axis Stage for Optical Element Alignment (광소자 정렬용 극초정밀 다축 위치 조정장치의 운동특성에 관한 연구)

  • Jeong S.H.;Cha K.R.;Kim H.U.;Choi S.B.;Kim G.H.;Park J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1219-1222
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    • 2005
  • As the optical communication is introduced to the backbone network at first and becomes a general communication method of network, the demand of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM(Wavelength Division Multiplexing) element increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this paper, the driving mechanism of ultra precision stage is studied with the aim of optimal design of stage. The travel and the resolution of stage are investigated. The hysteresis of the stage is generated because of PZT actuator. The hysteresis and the inverse hysteresis are modeled in X, Y, and Z-axis motion. The input data of desired displacement to the stage according to input voltage is obtained from the inverse hysteresis equation. In the result of experiments with the input data, the errors due to hysteresis are well compensated.

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A Study on the Optical Element Alignment of Ultra Precision Multi-Axis Stage (극초정밀 다축 위치제어장치의 광소자 정렬 특성에 관한 연구)

  • Jeong S.H.;Cha K.R.;Kim H.U.;Choi S.B.;Kim G.H.;Park J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1190-1193
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    • 2005
  • In recent years, as the demands of VBNS and VDSL increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM elements increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this paper, the optical alignment characteristics of multi-axis ultra precision stage were studied. The alignment algorithms were studied for applying to the ultra precision multi-axis stage. The alignment algorithm is comprised of field search and peak search algorithms. The contour of optical power signals can be obtained by field search and the precise coordinate can be found out by peak search. Two kinds of alignments, such as 1 ch. input vs. 1 ch. output optical stack, and 1 ch. input vs. 8 ch. output PLC stacks were performed for investigating the alignment characteristics.

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