• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.474-479
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• 1993

An interferometric fiber-optic magnetic field sensor is constructed by bonding a Co-Fe-B metallic glass transducer developed here by the melt-spun method to a single mode fiber arm in the fiber Mach-Zehnder interferometer and is tested. The bias field for the peak ac-sensitivity was observed near 0.97 Oe and the minimum detectable magnetic field was 3.9${\times}10^{-5}$ Oe(rms)/${\sqrt{Hz}}$ a 3 kHz. The output of the ac field sensor becomes saturated near the input signal level of 1 Oe(rms). The Co- Fe-B transducer exhibits peak response near 500 Hz.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.207-213
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• 1990

Natural convection heat transfer in rectangular air enclosure was studied interferometrically and numerically for the use of adiabatic and constant temperature horizontal boundary conditions. In the isothermal horizontal boundary case with the temperature difference ratio, .DELTA. $T_{v/}$.DELTA. $T_{H}$ .simeq. 1 temperature distribution in the enclosure is strongly stratified and the average Nusselt Number is higher than that of adiabatic horizontal boundary case.ase.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.35-42
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• 2004

In this paper, we report Mach Zehnder Interleaver of optical fiber type is fabricated by the fabrication system only for interfermeter design, and it is used $CO_2$ laser to adjust precisely the wavelength. The optical fiber is very sensitive in the thermal variation around. Thus, When fabrication the prototype, it is applied a technique to compensate the optical thermal effect because the center wavelength at the output is shifted according to the thermal variation around. it can he done by applying a substrate with high thermal expansion coefficient as well as an adjusting the position between two optical fiber couplers. Consequently, the output wavelength is shifted within 0.05 nm when the surrounding temperature varies until $60^{\circ}C$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.985-990
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• 2007

The method of enhancing visibility in optical fiber sensor was investigated by improving coherence length of light source. The optical feedback technique is used to enhance coherence length in fiber laser which generates laser in near infrared wavelength region and utilizes low loss characteristics of optical communication grade fiber. In this paper, the effect to coherence length by short and long optical feedback paths are investigated by using Mach-Zehnder interferometer technique. The effect to coherence length by changing optical feedback power and optical modulation are investigated. The spectral drift was calculated by measuring the degree of phase perturbation in unbalanced Mach-Zehnder interferometer having loom path difference. The short optical feedback path was effective to reduce spectral drift to 450kHz/sec and the long optical feedback path in combination with short optical feedback path was found to further reduce spectral drift to 50kHz/sec.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.306-312
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• 1998

To develop the multi-channel fiber-optic sensor array system, two-channel TDM(Time Division Multiplexing) fiber-optic sensor array was constructed and characterized. The sensor array topology was Mach-Zehender ladder type and PMDI(Phase-Matched Differential Interferometer) technique was used to exploit the efficiency of the array signal processing. By using a synthetic heterodyne demodulation technique, outputs of the two channels were monitored simultaneously. The sensitivities of channel #1 and #2 were measured ${\sim}60{\mu}rad/\sqrt{Hz}$ and ${\sim}80{\mu}rad/\sqrt{Hz}$, respectively. Crosstalk of sensors in the array was found to be approximately -36dB. Based on the results, we could conclude that TDM Mach-Zehnder ladder type sensor array can be used to detect the acoustic signal with stability and efficiency of the sensor array.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.125-129
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• 1990

One method for time-division multiplexing (TDM) of Michelson type fiber-optic interferometric sensor arrays is proposed and demonstrated experimentally. This method has some advantages; fewer fiber-optic components. low cost. and high reliability.bility.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.445-452
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• 1994

The automatic analysis of the wavefront of laser beam is simulated numerically, and is applied to get the wavefront of the output beam of LD-pumped cw Nd:YAG laser, experimentally. The automatic analysis tool was developed by utilizing Fourier analysis method, and its usefulness is proved through numerical simulation. The wavefront error due to the analysis tool is known to be less than A/30. In order to find the wavefront of Nd:YAG laser beam, its interference fringe is obtained from Mach-Zehnder interferometer. The wavefront calculated from the developed tool has the shape of nearly spherical wavefront and the maximum distortion is about 0.8 .A.. 8 .A..

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.119-123
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• 2010

The transmission performance of 10Gb/s optical duobinary transmitters implemented by using a Mach-Zehnder(MZ) modulator and an optical delay interferometer is presented. We investigated the theoretical impact of transmission systems by the modulator driving voltage ratio(=driving voltage/switching voltage) and the optical interferometer time delay to improve transmission distance using computer simulation. By reducing the driving voltage ratio and optimizing the partial bit time delay, the transmission performance has been improved greatly.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.31-38
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• 2004

The wavelength variation of a scanned fiber laser is analyzed using quadrature sampling technique. By time delayed sampling of a phase modulated Mach-Zender interferometer, the wavelength information can be precisely determined regardless of the nonlinearity in the Fabry-Perot wavelength filter which scanned the fiber laser. A wavelength readout resolution of ～20 pm was obtained at 2 KHz M-Z modulation frequency, and it was shown that the resolution could be improved in case of using an electro-optic phase modulator.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.192-193
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• 2003

광센서로 이용되는 광섬유 브라고 격자(이하 FBG)는 주변 환경에 대한 반응을 공진파장의 이동으로 나타내기 때문에 이것을 측정하기 위해서는 광 스펙트럼 분석기(OSA)가 반드시 필요하다 그러나 상용화된 광 스펙트럼 분석기는 고가이며 부피가 커서 광섬유 격자가 광센서로 상용화되는데 걸림돌이 되어 왔다. 이런 단점을 보완하기 위해서 많은 연구가 진행되어 왔으며 그 중에서 가장 잘 알려진 기술로는 Mach-Zehnder Inteferometer(MZI) 같은 간섭계를 이용한 방법과 Fabry-Perot (FP) filter, acousto-optic filter, FBG-based filters 등과 같은 변조기를 사용하여 광신호를 전기 신호로 바꿔 실시간으로 측정하는 방법들이 있다. (중략)