• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.10-15
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• 2013

In this paper, we propose a Lyot-type optical fiber comb filter based on a polarization-diversity loop structure (PDLS), which has flat-top pass bands and multiwavelength switching capability. Generally, the PDLS can remove the dependency of the filter on input polarization. The proposed filter is composed of a polarization beam splitter, two half-wave plates (HWPs), and two polarization-maintaining fiber loops concatenated with a $60^{\circ}$ offset between their principal axes. By controlling two HWPs, it can operate in a flat-top band mode or a lossy flat-top band mode with an inherent insertion loss of ~3.49dB. In particular, flat-top bands can be interleaved in both modes, which cannot be realized in a Lyot-Sagnac comb filter based on a fiber coupler. Compared with Solc-type high-order comb filters with the same order, the proposed filter shows sharper transition between pass and stop bands.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.240-244
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• 2002

We proposed a novel temperature sensor based on the phenomena that the phase difference between principal polarization states in an optical retarder is a function of temperature. The polarization state of an optical beam is changed as it passes through the optical retarder, with the change dependent on the temperature. The temperature of the optical retarder is determined by comparison of the power difference between principal polarization states. A temperature sensor was successfully implemented using a polarization maintaining fiber of length 100 mm as the optical retarder. The change rate of phase difference on temperature was 0.236$^{\circ}C$$_{-1}$ and the measurement error was $\pm$0.038$^{\circ}C$ over the temperature region of -2.6$^{\circ}C$~3.4$^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.487-492
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• 1993

A polarization maintaining fiber optic gyroscope was constructed having an optical loss of about 25 dB. Using the earth rotation rate as a reference, the long term stability of better than $3^{\circ}/hr$ and the rms short term noise of $0.6^{\circ}/hr/{\sqrt{Hz}}$ were obtained.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.186-187
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• 2001

광섬유 브래그 격자를 이용한 고정밀도 센서 시스템은 불균형(unbalanced) 마하 젠더 간섭계를 이용한 interrogation 기법을 많이 사용하고 있다. 그러나 간섭성을 이용한 interrogation 기법은 작은 온도 변화, 진동과 같은 외부 환경 변화에 매우 민감하다 이 논문은 불균형 마하 젠더 간섭계 대신 편광 유지 광섬유 (polarization maintaining fiber , PMF) 루프 미러(loop mirror)를 이용한 interrogation 시스템을 구현하였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.405-406
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• 2008

In this paper, we will discuss the spectral characteristics of fiber Bragg gratings (FBGs) inscribed in two different types of polarization-maintaining fibers with side holes. One showed high signal-to-noise ratio (SNR), narrow bandwidth and high bending sensitivity, while the other one showed insensitivity to bending due to the small size of the side holes.

• Current Optics and Photonics
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• v.7 no.1
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• pp.33-37
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• 2023

Real-time adaptive control of laser output polarization is presented in a 10-W-level non-polarization-maintaining (non-PM) fiber amplifier. While the output polarization from a non-PM fiber amplifier tends to be irregular, depending on output power, time, and perturbation, closed-loop polarization control can maintain the polarization extinction ratio at higher than 20 dB. Real-time polarization control can attain the target linear polarization mostly within 1.4-25 ms and shows stability against external perturbations. This approach can satisfy both linear polarization and high output power in a non-PM amplifier, and facilitates optimization of laser performance and maintenance-free operation.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.19-24
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• 2008

In this paper, we describe the fabrication process and the characteristics of polarization maintaining photonic crystal fibers (PM-PCFs). The PM-PCF is fabricated by stack-and-draw method, i.e., stacking silica capillary tubes (making a PM-PCF preform) and drawing to optical fiber. Firstly, a PM-PCF preform is formed by stacking two kinds of capillary tubes around a solid silica rod and jacketing these stacked tubes with an outer silica tube (out-jacket tube). Later, the desired preform is drawn to a fiber in a high temperature drawing tower. We also compare the polarization properties such as polarization dependent loss, birefringence, and differential group delay of the fabricated PM-PCF with those of the conventional PANDA PM fiber.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.40-41
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• 2002

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.30-35
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• 2003

In this paper, the transverse strain was measured using polarization maintaining fiber Bragg grating(PMFBG) sensor. PMFBG sensor was fabricated using phase mask and Excidmer laser. The reflected wavelength of PMFBG sensor had dual peaks due to intrinsic birefringence. To find the polarization axes, peak sensitivity was measured under compression test. The signal characteristics of PMFBG sensor were also examined in embedding condition. The embedded PMFBG sensor in epoxy block was loaded for the transverse strain measurement, The wavelength-swept fiber laser(WSFL) was used to construct the PMFBG sensor system. Experiments showed that the PMFBG sensor could successfully measure the transverse strain.

• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.270-273
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• 1998

We have demonstrated the wavelength tunable ultrashort pulse fiber ring laser proposed the novel method for measuring the cavity loss from relaxation oscillation frequency and the pump power. To suppress the polarization instability the laser cavity is configured with polarization maintaining fibers and to control the center wavelength a 2.4 nm bandwidth tunable wavelength filter was inserted in the cavity. The laser has 8 picosecond pulse width, 10 GHz repetition rate and 1.2 mW average power in 1530-1560 nm operation range.