• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1048-1055
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• 2005

The formula to calculate a variation of optical path length of single crystal by the electric field was derived by this study. The formula was applied to $Bi_{12}SiO_{20}$ single crystal. The results are as follows. In case of the applied electric field in the body diagonal direction and the passing light along the same direction, the variation of optical path length had the largest value. The symmetry of the space distribution of optical path length satisfied $E3C_2\;8C_3$, the set of elements of the symmetry of $Bi_{12}SiO_{20}$ single crystal. The property which gave the largest influence to the variation of optical path length is the strain of length by the Inverse piezoelectric effect. The second influence, is the variation of the refractive index by the electro-optic effect. The variation of optical path length by the inverse piezoelectric effect and by the electro-optic effect have a reverse sign each other.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.184-185
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• 2005

• Journal of the Optical Society of Korea
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• v.17 no.4
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• pp.296-299
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• 2013

A low density lipoprotein (LDL) cholesterol testing device, structured with serial reflected face-to-face mirror (SRM) allowing spectrophotometry measurements, is presented. The spectrophotometry has been employed to measure the amount of light that a sample absorbs, but it generally should have had path length longer than 10 mm to secure enough sensitivity. Such requirement of path length has often been problematic in implementing a thin type of lab on a disc (LOD). We developed the SRM system which was implemented in a detection chamber with 1.4mm thickness, providing path length longer than 10mm, and thus straightforwardly being applicable to LOD as thin as a compact disc. The experimental results show that the SRM system gives not only a much thinner design compared to the conventional spectrophotometry-based LOD but also a comparable performance to already commercialized spectrometers.

• 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 the Optical Society of Korea
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• v.15 no.4
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• pp.380-385
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• 2011

Common-path interferometers are widely used for endoscopic optical coherence tomography (OCT) because an arbitrary arm length can be chosen for the endoscopic imaging probe. However, the scheme suffers from the limited range of the sample position distance from the end of the imaging probe because the position between the reference reflector and the sample is limited by the optical path-length difference (OPD) to induce an interference signal. In this study, we developed a novel method for compensating the arbitrary sample position in common-path swept-source OCT by adding an extra Mach-Zehnder interferometer in the post-path of the interfered optical signal. Theoretical analysis and an experimental demonstration of imaging depth tuning for the flexible sample position of an endoscopic OCT image are discussed. After post-tuning of sample position distance, the positioning limitation between the reference reflector and the sample can be solved for various sample positions over a range of 26 mm for the cross-sectional images of a fish eye sample.

• The Journal of the Acoustical Society of Korea
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• v.21 no.1E
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• pp.25-30
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• 2002

We report on the development of a fiber optic hydrophone consists of a sensing Michelson interferometer and a compensating Mach-Zehnder interferometer for optical path length compensation. The double interferometer configuration has the following advantages: the hydrophone can be made more small; a laser source with a relatively short coherence length can be used; and the compensating interferometer can be located near the signal processing electronics, far away from the sensing interferometer and noise introduced by reference arm can be greatly reduced. The performance of the hydrophone is evaluated experimentally by immersing the sensing interferometer in a water tank to detect underwater acoustic signals generated by an acoustic wave projector. Experimental results show that over the frequency range of 1 to 4 kHz, the hydrophone has an almost flat response with an average normalized sensitivity of -302 dB re 1/ μ Pa.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.35-42
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• 2003

In this paper, we classified the wavelength reservation mechanisms of optical burst switching (OBS), and investigated the path length priority effect of the offset time/delayed reservation (OT/DR)-based scheme like the just-enough-time (JET) protocol. And, we showed that the fiber delay line (FDL)-based scheme can avoid the path length priority effect in multiple hop network environments. Also, we proposed a novel FDL/DR with hop-by-hop priority increasing (HPI) scheme which can improve the end-to-end throughput by increasing the priority of bursts hop-by-hop using the input FDLs at each node. The simulation results showed that the proposed FDL/DR with HPI scheme could avoid the path length priority effect and enhance the end-to-end throughput in multiple hop network environments.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.63-68
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• 2022

Two wavelength reconfigurable optical nodes are designed. One for 20km or shorter link length, and the other for up to 60km link length. While the first one requires no dispersion compensation, the latter needs dispersion compensation fiber included in the node, which requires additional optical amplifier to compensate the insertion loss of DCF. We calculate all the optical path losses in both cases using the typical value of optical components in the market to see the feasibility of the designed optical node. The minimum received power in the node is calculated to be -21.5dBm without DCF and -12.5dBm with DCF, respectively. These received powers are above the receiver sensitivity both for OC-48 and OC-192 according to the previous work.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.273-274
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• 2008

We present a quantitative phase microscopy for live cells. This method uses the principles of common path inteferometry and single shot phase image. This system has the ability to measure live cells quantitatively with subnanometer path length stability and millisecond scale aquisition time.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.113-118
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• 1989

By using the single mode optical fiber, we fabricated Fiber-optic Fabry-Perot interferometer (FFPI). The change over a wide range in the optical path length of a FFPI is observed. The temporal movement of the interference fringes by external condition to P.Z. T) is converted to circular motion on an oscilloscope display and then recorded with a micro-computer. The two output voltages of the D/A converters are applied to X and Y terminals of oscilloscope to display circular motion on oscilloscope. Thus the direction of phase shift can be determined with observing the direction of circular motion. The variation of the optical length can be measured by calculating the angle of spot of circle with an accuracy of λ/90 wave length due to variation of temperature in this system 2.7x10-4$^{\circ}C$.