• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1707-1713
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• 2000

We have proposed a tunable optical ADM using a fiber-optic transversal filter which is composed of fiber couplers and metal-film coated fiber-optic tapped delay-lines with a flat spectral response in abroad range of wavelength. Simulation results show that the optical loss at the DROP and PASS wavelengths of the OADM is negligible and the wavelength tunability is 0.78${\mu}{\textrm}{m}$/ps for the unit time delay of 2 ps. In order to investigate the effects of wavelength drift of the imput optical signal on the OADM the loss at the DROP port and the crosstalks to the other ports have been calculated. The maximum bit rates have been calculated at 46.26 Gb/s for the input Gaussian pulse width of 10 ps.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.20-26
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• 1997

In this paper, we propose a tunable drop/pass filter in the form of composed of Mach-Zehnder interferometer, to which a fiber grating and two PZTs are attached. The proposed drop/pass filter drops a part of signal power at a specific wavelength and pass the remnant of the signal to the next node in WDM network. Our simulation results show that the optical feedback is less than 2% and the drop to pass ratio can be made bigger than 10% if the phase difference between the two arms is within .+-.0.2.pi. from (2m+1).pi.. Also, the output powers at drop prot and pass port are measured to be maximum at the phase difference of .pi./2 and .pi., respectively, as expected.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.216-222
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• 2006

We propose the use of the Gaussian-curve fitting algorithm for the improvement of measurement accuracy in wavelengthscanned Fabry-Perot filter based demodulation systems. The peak locations of FBG sensors were calculated from the fitted curves rather than from distorted PD profiles, resulting in much better measurement accuracy than that of the highest-peak search algorithm. Also, the algorithm was proved to minimize measurement uncertainty of spectrally-distorted grating sensors. From our experimental results, a temperature resolution as small as ${\sim}0.3^{\circ}C$ was readily achieved by use of the Gaussian-curve fitting algorithm whereas the highest-peak search algorithm gave a temperature resolution larger than ${\sim}4^{\circ}C$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.64-71
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• 2006

We developed a fiber-optic temperature sensor system, with 10 fiber Bragg gratings, for abnormal high-temperature monitoring in power systems. We used Gaussian line-fitting algorithm to compensate the spectrum distortion in the wavelength-scanned Farby-Perot filter demodulation scheme. Compared with highest-peak-detection method, the proposed algorithm substantially reduced measurement errors. The overall measurement error was less than 1[%] compared with the reference thermocouple and the linearity error was 0.37[%].

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.44-49
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• 2003

In case of an extrinsic Fabry-Perot interferometric sensor, the phase compensating technique is particularly necessary in applying the interferometer to detecting acoustic emission signals because of signal-fading problems. The technique makes it possible to maintain the phase at the quadrature point. In this paper, we developed the stabilization control sensor system that is composed of a broadband light source, a tunable Fabry-Perot (F-P) filter and a control-circuit board. A tension test of a composite specimen was performed to verify if the developed system could compensate the phase change induced from the tension strain and keep the phase at the quadrature point.

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.211-216
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• 2012

We report a resonance fiber Bragg sensor interrogation based on a Fourier domain mode-locking (FDML) laser. The FDML laser is constructed based on a conventional ring laser cavity configuration with fiber Fabry-Perot tunable filter (FFP-TF). There are two sensor parts which are composed with two FBGs inside the laser cavity. Each sensor part provides a separate laser cavity for the FDML laser. The resonance frequencies of the laser cavities are 46.687 kHz and 44.340 kHz, respectively. We applied a static and a dynamic strain on the FBG sensor system. The slope coefficients of the measured relative wavelength shift and relative time interval from the static strain are found to be $0.61pm/{\mu}{\epsilon}$ and $0.8ns/{\mu}{\epsilon}$, respectively.