• 한국음향학회지
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• 제30권1호
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• pp.33-41
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• 2011

음압을 감지할 수 있는 Sagnac 간섭계 센서와 온도 및 스트레인을 측정할 수 있는 FBG센서를 결합한 새로운 형태의 하이브리드 광섬유 센서 시스템을 구축하기 위하여 입력 광원인 CW를 TLS로 대체할 필요가 있어 이에 따라 광원의 변화와 맨드릴 재료의 변화에 따른 광섬유 센서의 응답 특성 연구가 필요하게 되었다. 제작된 맨드릴 재료는 PTFE와 PTFE에 카본을 섞어 만든 두 종류로 선택하여 중공 원통형 맨드릴 겉면에 광섬유를 18 m 감아 광섬유 센서로 제작하였다. CW 광원에 대하여 음원의 입력 주파수를 1 kHz~20 kHz까지 바꾸어 가며 트랜스포머 오일이 채워진 유조에서 실험하였다. 또한 FBG와 맨드릴형 광섬유 센서를 결합한 하이브리드형 광섬유 센서 시스템을 구성하고 TLS 광원을 입사광으로 실험하였다. 실험 결과 PTFE 센서의 탐지 크기는 카본 센서 탐지 크기보다 높게 나타났고 맨드릴 재질의 탄성계수 값이 적을수록 커진다는 이론 결과와 잘 일치함을 보였다. CW 광원과 TLS 광원에서 응답한 PTFE 센서의 특성을 주파수별로 상호 비교하여 보면 광원이 CW일 때 보다 TLS일 때 응답 특성이 우수함을 알 수 있었다. 본 연구를 통하여 TLS를 이용한 광섬유 센서는 FBG와의 하이브리드 시스템에 적용 가능하리라 사료된다.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.405-409
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• 2009

A polarization-independent multiwavelength-switchable fiber filter is proposed based on a polarization beam splitter and fiber coupler, which can function as a polarization-independent transmission or reflection-type interleaving filter. The proposed filter consists of a polarization beam splitter and a Sagnac birefringence loop composed of a 50:50 coupler, high birefringent fibers, and two quarter-wave plates. In the proposed filter, a transmission-type interleaver with a channel isolation > 18 dB or a reflection-type one with a channel isolation of ${\sim}3$ dB, whose channel spacing and switching displacement were 0.8 and 0.4 nm in common, respectively, could be obtained. A channel interleaving operation could be performed by the proper control of waveplates within the Sagnac birefringence loop.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.250-251
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• 2000

모드록킹된 광섬유 레이저 자이로스코프(ML-FLaG)$^{(1)}$ 는 일반 거울과 Sagnac 루프 거울로 이루어진 공진기 안에 이득 매질이 포함된 광섬유 레이저의 형태를 가진다. Sagnac 루프 거울을 서로 반대 방향으로 진행하는 두 빛 사이의 위상차를 변조시키면 루프 거울의 반사율이 변조되는데, 여기서 위상 변조 주파수를 공진기의 종모드 간격과 일치시키면 공진기 왕복 주기에 두 개의 펄스가 들어가는 모드록킹된 펄스열을 얻을 수 있다. 이 두 펄스 사이의 시간 간격은 회전율에 따라서 변하기 때문에, 두 펄스 사이의 시간 간격 변화를 측정하면 회전 각속도를 알아낼 수 있다. (중략)

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.111-112
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• 2007

The spatial coherence function of laser beam was measured by using a Sagnac interferometer and self referencing technique. For laser beam passing through a narrow slit, absolute value of measured spatial coherence function becomes more symmetric as the slit size is reduced. For diverging beams, the spatial coherence function shows fast oscillations in its real and imaginary parts. We explain this by using a Gaussian Schell-model. One can use this measurement method to study and characterize the property of light field coming out of small sample.

• 산업기술연구
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• 제26권A호
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• pp.95-99
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• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and Fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1714-1716
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• 2002

Optical fiber sensor is a subject which has been attracted considerable attention in recent year. Especially, it is being developed for the detection and location of partial discharge in oil-filled transformers. In this paper, we propose and experimentally demonstrate directivity and sensitivity of a hollow cylindrical mandrel sensor. The sound source is a PZT actuator of hollow cylinder type. Several layers of the fiber laminated around the mandrel surface and experiments were performed on three axis modes. The experimental results can be applied to analyze detected signals optimally.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.62-66
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• 2002

The preliminary results on the application of optical fiber sensor(OFS) for locations of ultrasonic signals in underwater are presented and analyzed. The OFS utilizing the principle of Sagnac interferometry was designed and the hollowed cylindrical mandrel wound by single mode optical fiber was used as sensing component. The ultrasonic signal source was simulated by the PZT actuator operated with function generator. It has been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor and accurate location of ultrasonic signal could be carried out using two OFSs.

• 한국전기전자재료학회논문지
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• 제16권9호
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• pp.838-841
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• 2003

This paper shows results on the application of optical fiber sensors(OFS) for locations of ultrasonic signals in silicon insulating oil. The OFS system based on the principle of Sagnac interferometry has been designed and established for this work. The hollowed cylindrical mandrel wound by single mode optical fiber was used as a sensing component and ultrasonic signals which simulate the partial discharge In the oil have been generated by PZT actuator operated with function generator. The experimental results shows that the OFS has a excellent performance for the PD location with resolutions less than 1$^{\circ}C$ error range in the miniature insulating oil tank.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.187-189
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• 2008

The spatial coherence function of multy-mode beam was measured by using a Sagnac interferometer and self referencing technique. For leaner polarization laser beam passing through a multy-mode fiber, its change value of spatial mode and polarization from stress of faber and input coupling angle. And each spatial mode have each polarizations, when we simulation Wigner distribution function and Spatial Correlation function of spatial multi-mode beam by using Hermit Gaussian modes leaner sum. We measured spatial coherence function of using by multy-mode fiber. One can use this measurement method to study and characterize the property of multy-mode light field coming out of GRIN multy-mode fiber.

• Journal of the Optical Society of Korea
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• 제11권2호
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• pp.71-75
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• 2007

The spatial coherence function of a laser beam was measured by using a Sagnac interferometer and self referencing technique. For a laser beam passing through a narrow slit, the absolute value of the measured spatial coherence function becomes more symmetric as the slit size is reduced. For diverging beams, the spatial coherence function shows fast oscillations in its real and imaginary parts. We explain this by using a Gaussian Schell-model. One can use this measurement method to study and characterize the property of the light field coming out of a small sample.