• Title/Summary/Keyword: Fabry-Perot filter

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4-channel optical frequency division multiplexing using the fiber Fabry-Perot filter (광섬유 파브리-페로 필터를 이용한 4채널 광주파수 다중화)

  • 류갑열;주무정;박창수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.8
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    • pp.133-139
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    • 1995
  • In this paper, the frequency separation locking and interval stabilization of 4-channel DFB-LDs have been demonstrated using a fiber Fabry-Perot filter with an free spectral range of 100GHz. Frequency fluctuation and locking range of each channel were appeared to be within 15MHz and over 12GHz, respectively. Back-reflection curve from the fiber Fabry-Perot filter was used for the extraction of an error signal in order to increase the number of accomodable channels and extinction ratio.

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The wavelength locking system of the fabry-perot filter for WDM (WDM을 위한 Fabry-perot 필터의 로킹 시스템)

  • 송준용;이호준
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.6
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    • pp.58-64
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    • 1997
  • The wavelengt lockin gsystem of the optical fabry-perot filter theoretially derived and experimentally realized by using the ithering method in order to compensate the laser wavelength drift increasing the BER of the WDM system. The deviation between the laser wavelength and the optical filter center wavelength is compensated by applying a suitable voltage to the PZT. Accordingly, the laser wavelength selected by the fabry-perot filter always maintains the condition of maximum transmission powr. A wavelength locking system has been demonstrated using a fiber fabry-perot filter with a free spectral range of 80nm and an FWH of 1nm. The voltages of the sine wave generated for dithering was 20mV and 10mV, the frequency was 2kHz and center wavelength of the tunable laser was 1550nm. In this paper, the locking system have 20ms of locking time and 2nm of locking range.

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Design and performance study of fabry-perot filter based on DBR for a non-dispersive infrared carbon dioxide sensor (비분산적외선 CO2 센서를 위한 DBR기반의 패브리 페로-필터 설계 및 성능 연구)

  • Do, Nam Gon;Lee, Junyeop;Jung, Dong Geon;Kong, Seong Ho;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.30 no.4
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    • pp.250-254
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    • 2021
  • A highly sensitive and selective non-dispersive infrared (NDIR) carbon dioxide gas sensor requires achieving high transmittance and narrow full width at half maximum (FWHM), which depends on the interface of the optical filter for precise measurement of carbon dioxide concentration. This paper presents the design, simulation, and fabrication of a Fabry-Perot filter based on a distributed Bragg reflector (DBR) for a low-cost NDIR carbon dioxide sensor. The Fabry-Perot filter consists of upper and lower DBR pairs, which comprise multilayered stacks of alternating high- and low-index thin films, and a cavity layer for the resonance of incident light. As the number of DBR pairs inside the reflector increases, the FWHM of the transmitted light becomes narrower, but the transmittance of light decreases substantially. Therefore, it is essential to analyze the relationship between the FWHM and transmittance according to the number of DBR pairs. The DBR is made of silicon and silicon dioxide by RF magnetron sputtering on a glass wafer. After the optimal conditions based on simulation results were realized, the DBR exhibited a light transmittance of 38.5% at 4.26 ㎛ and an FWHM of 158 nm. The improved results substantiate the advantages of the low-cost and minimized process compared to expensive commercial filters.

Si/SiO2 Multilayer-based Fabry-Perot Filter for 4.26 ㎛ Filtering in Carbon Dioxide Detection (이산화탄소 감지를 위한 4.26 ㎛ 필터용 poly-Si/SiO2 다층 박막 기반의 패브리 페로-필터)

  • Do, Nam Gon;Lee, Junyeop;Jung, Dong Geon;Kong, Seong Ho;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.30 no.1
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    • pp.56-60
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    • 2021
  • In this study, the relationship between the transmitted light intensity and full-width-at-half-maximum (FWHM) of a Fabry-Perot filter was investigated. The measured refractive indices and absorption coefficients of the fabricated thin films were applied to the Fabry-Perot filter via simulations using optical software. Although considerable research has been conducted on Fabry-Perot filters, this study focused on the usefulness of 4.26-㎛ infrared filtering in carbon dioxide detection. Optical analysis was performed considering the effects of the thickness, refractive indices, and number of thin films in a distributed Bragg reflector. Ultimately, a clear trade-off relationship was observed wherein the transmitted light intensity decreased as the number of multilayers increased; however, the FWHM was observed to be narrower.

Equi-spaced multichannel stabilization with a reference frequency from ($^13C_2H_2$) molecules and optical fiber fabry-perot filter (아세칠렌가스($^13C_2H_2$)분자의 흡수선을 이용한 기준 광신호 및 광섬유 파브리-페로 필터에 의한 등간격 다중채널의 안정화)

  • 이현재;류갑열;이동호;박창수
    • Korean Journal of Optics and Photonics
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    • v.8 no.1
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    • pp.68-72
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    • 1997
  • Using one of the absorption lines of $^{13}C_2H_2$ molecules near the zero dispersion wavelength(1549.49nm) of dispersion shifted fiber, we stabilized center frequency of an optical fiber Fabry-Perot filter. The free spectral range of the filter is 100 GHz for 100 GHz channel allocation. For equi-spaced three channel multiplexing, channel locking of three DFB-LDs to transmission peaks of the fiber Fabry-Perot filter was tried. To investigate the effect of dithering current applied to each DFB-LD, the change of DFB-LD linewidth was measured.

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An Automatic Control of Reflective Wavelength of TFBG Using Fabry-Perot Filter (Fabry-Perot 필터를 이용한 가변 광섬유격자의 반사파장 자동조절)

  • Pan, Jae-Kyung;Kim, Ji-Do;Jeon, Keum-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.4C
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    • pp.430-436
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    • 2009
  • In this paper, we propose and describe our implementation of an automatic control system for the center wavelength of a fiber Bragg grating. The proposed system consists of a Fabry-Perot filter and cantilever structure controlled by a step motor interfacing computer. We consider the change of the center wavelength and the reflective spectrum shape for a given FBG according to the translation distance of the push stick and the cantilever thickness variation. The proposed system can control the center wavelength of a FBG with a resolution of 0.01 nm by applying compression or extension to the FBG. The proposed system has characteristics that keep the desired wavelength of the FBG with a variation of environmental conditions.

Linear interrogation of fiber Bragg grating sensor array using time-delayed quadrature sampling technique (시간지연 샘플링을 이용한 광섬유 격자 센서어레이의 선형 복조)

  • 김종섭;송민호
    • Korean Journal of Optics and Photonics
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    • v.15 no.1
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    • pp.34-38
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    • 2004
  • A fiber laser of which wavelength was scanned by an intra-cavity FP (Fabry-Perot) filter was used to interrogate a fiber Bragg grating strain sensor array. We calculated the wavelength variation of the fiber laser using quadrature signal processing with an unbalanced M/Z (Mach-Zehnder) interferometer and time-delayed sampling technique. The calculated wavelengths are mapped to corresponding temporal reflection peaks from the sensor array, which enables more accurate and stable interrogation without the problems caused by the FP filter's nonlinear characteristics. Wavelength resolution of ∼20 pm was obtained in our experimental setup, which could have been greatly enhanced with faster phase modulation.