• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.57-62
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• 2004

We report the fiber-optic current sensors composed of a side-polished single-mode fiber with the thermo-optic Polymer layer and the metal wire as a heater. The index change of polymer layers caused by the resistant heat of the metal wires induces the optical attenuation through the evanescent field of the side-polished single-mode fiber. Two types of the sensors are proposed and their characteristics as a current sensor are investigated.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.233-236
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• 1999

We have constructed a narrow-linewidth single-longitudinal-mode unidirectional $Er^{3+}$ -doped fiber laser using a fiber Bragg grating incorporated by a three port optical circulator with a compact configuration. Using a conventional delayed self-heterodyne detection technique with Mach-Zehnder interferometer a linewidth of 5 kHz was measured. In a single-longitudinal-mode operation, output power of up to 2.7 mW at 1548 nm were obtained for a launched pump power of 43 mW at 980 nm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.4
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• pp.278-285
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• 1990

It is well know that optical oupler that is composed of the polished single-mode optical fiber can separate two arbitrary wave lengths. Wavelength division ranges of the WDM optical coupler that is made of the bending fiber with radius R vary with the center wavelength of the signal and spacing between two cores. In this paper, when optical fiber is fixed with the radius R, We proposed the spacing between two cores that can provide minimum division range. Also, We proposed the minimum radius R necessary to separate two arbitary wavelengths of the signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.296-307
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• 1985

The reults of the interlaboratory measurement comparison of the multimode and single mode fiber papameters are reported. 7 multi-mode fiber spools and 4 single mode spools are used and 5 independent domestic organizations (ETRI & 4 optical fiber manufacturing companies) are participated in the comparison study. Our results are compared with those of the comparison studies conducted in the foreign countries.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1198-1203
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• 1991

A single w& optical fiber strain gauge subjected to the excited PZT-plate is presented which was obtained using a Mach-Zehnder interferometer. This paper has been performed the considerations to the experimental situation In which the dynamical behavior of a optical fiber strain gauge is illustrated. A comparison is reported between the dynamic response of a optical fiber strain gauge and the semiconductor strain gauge in the frequency range 5-50Hz. This result is shown in very good usage as the dynamical measurement of the low strain below l.mu..epsilon. by this system.

• Journal of the Optical Society of Korea
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• v.13 no.4
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• pp.416-422
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• 2009

We have demonstrated a highly efficient cladding-pumped ytterbium-doped fiber laser, generating $>$2.1 kW of continuous-wave output power at 1.1 μm with 74% slope efficiency with respect to launched pump power. The beam quality factor ($M^2$) was better than 1.2. The maximum output power was only limited by available pump power, showing no evidence of roll-over even at the highest output power. We present data on how the beam quality depends on the fiber parameter, based on our current and past fiber laser developments. We also discuss the ultimate power-capability of our fiber in terms of thermal management, Raman nonlinear scattering, and material damage, and estimate it to 10 kW.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.620-621
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• 2015

The system performances of WDM channel signals as a function of the number of fiber spans in optical link with the uniform distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS) for the compensation for the distorted WDM signals due to the group velocity dispersion (GVD) are evaluated and compared.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.604-611
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• 1990

One of the confronting problems in using optical fibers under radiation environments is producing of color centers in optical materials due to nuclear radiation. These centers increase transmission loss by absorbing propagating light. In this study, the radiation effects on optical fiber are studied theoretically. Also, optical attenuation induced by \ulcorner-ray irradiation from Co**60 for single mode and multimode optical fibers is measured at the optical wavelength of 0.85\ulcorner and 1.3\ulcorner, and the results are analyzed. Gammaray is irradiated for 5hours at the rate of 300rads/min, which is corresponding to 90 krads of integrated dose. In case of multimode optical fibers, the induced loss at 0.85\ulcorner wavelength has been twice higher than that at 1.3\ulcorner. The loss in multimode fibers has been significantly larger by 7-20 times than that in single mode fibers, dependently on fiber materials at 1.3\ulcorner.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.48-53
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• 1997

Volume hologram was recorded using reference beam form optical fiber taper. A singel mode fiber was chemically etced to make a taper structure, and we showed experimentally that the referencing by the irregular beam pattern from this taper structure could increase the storage density of photorefractive volume hologram. The spatial selectivity of the volume hologram with this method was increased by two times compared to the normal single mode fiber referencing case. A theoretical analysis with randomly phased plane model also confirmed the results.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.376-381
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• 2015

Transmission characteristics of long-period fiber gratings (LPFGs) fabricated by periodically etching a conventional single-mode fiber (SMF) are investigated. After coating the SMF with photoresist, the cladding of the SMF is symmetrically and periodically removed by using a wet etching technique resulting in the formation of the LPFG. Tensile strain reinforces the coupling strength between the core and the cladding mode based on the photoelastic effect. The extinction ratio of the SMF-based LPFG at a wavelength of 1550.8 nm is measured to be -15.1 dB when the applied strain is $600{\mu}{\varepsilon}$. The ascent of ambient index shifts the resonant wavelength to shorter wavelength because of the increase of the effective refractive index of the cladding mode. The extinction ratio is diminished by increase in the ambient index because of the induction of the optical attenuation of the cladding mode. The transmission characteristics of the proposed LPFG with variations in torsion are also measured. The photoelastic effect based on torsion changes the extinction ratio and the resonant wavelength of the proposed SMF-based LPFG. The polarization-dependent loss of the LPFG is also increased by torsion because of the torsion-induced birefringence. The polarization-dependent loss of the LPFG at torsion of 8.5 rad/m is measured to be 3.9 dB.