• Korean Journal of Optics and Photonics
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• v.26 no.6
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• pp.306-311
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• 2015

We report the characteristics of a single-wavelength-tunable fiber laser using a polymer waveguide Bragg grating (PWBG) wavelength filter. The output of the laser depends on environmental conditions, such as temperature and polarization states in the laser cavity. Wavelength tuning can be achieved, about 16.29 nm from 1548.24 nm to 1531.95 nm, according to the electric power applied to the PWBG wavelength filter. The achieved efficiency slope is about -0.16 nm/mW. A side-mode suppression ratio (SMSR) of more than 35 dB can be obtained by adjusting the polarization state in the laser cavity. A stable wavelength-tunable fiber laser can be achieved using the PWBG wavelength filter with a TEC module and a polarization-maintaining fiber.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1265-1266
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• 2015

본 논문에서는 PMF와 FBG로 구성된 PDL 기반 사냑 간섭계를 이용하여 편광 간섭형 광섬유 압력 센서를 구현하였다. 여러 종류의 PMF들에서 압력 민감도를 비교하기 위해, 서로 다른 세 종류의 보우-타이형 PMF를 센서부로 사용하였다. 구현된 광섬유 압력 센서를 이용하여 0~0.3 MPa의 범위에서 압력 측정을 수행하였으며, 최대 압력 민감도는 근사적으로 -15.07 nm/MPa로 측정되었고, 센서의 선형성을 나타내는 $R^2$값은 ~0.992로 측정되었다. 제안된 센서는 FBG를 이용하여 외부 온도 변화의 보상이 가능하면서도, 이전의 편광유지 광자결정 광섬유 기반 압력 센서에 비해 압력 민감도를 4배까지 증가시킬 수 있었다.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.480-486
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• 1993

We propose and demanstrate a fiber laser as a sensor, whose output is the frequency of beat signals between eigenpolarization modes of the fiber laser. For the measurement of lateral stress, proportional constant of 4.8 kHz/gram is obtained with a good linearity. For the measurements of temperature and longitudinal strain applied to the polarization maintaining fiber laser, proportional constants of 30 kHz/$^{\circ}C$ -cm, and 43 kHz/${\mu}m$, respectively, are obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.73-76
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• 1997

A low loss x-cut LiNbO$_3$ optical waveguide was fabricated by Ti in-diffusion and the guided-mode properties and total insertion loss of pigtailing with polarization maintaining fiber(PMF) were investigated and measured at optical wavelength 15507. For formaing the waveguide, the parameters of diffusion Ti thickness, waveguide line-width, length, diffusion temperature, time and atmosphere were set 1400$\AA$, 8${\mu}{\textrm}{m}$, 3.3cm, 105$0^{\circ}C$, 8 hours and wet bubbled oxygen, respectively. and then After the polishing and pigtailing, it showed that total insertion loss was -4.1dB for TM mode, -5.5dB for TE mode, and mode size, that is, horizontal/vertical sizes were 13.87/18${\mu}{\textrm}{m}$ for TM mode, 9.61${\mu}{\textrm}{m}$/6.5${\mu}{\textrm}{m}$ for TE mode.

• Current Optics and Photonics
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• v.2 no.6
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• pp.519-524
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• 2018

We propose a transverse load sensor with reconfigurable measurement accuracy based on a microwave photonic filter in the $K_u$ band, incorporating a polarization-maintaining fiber Bragg grating. A prototype sensor with a reconfigurable measurement accuracy tuning range from 6.09 to 9.56 GHz/(N/mm), and corresponding minimal detectable load range from 0.0167 to 0.0263 N/mm, is experimentally demonstrated. The results illustrate that up to 40% manufacturing error in the grating length can be dynamically calibrated to the same corresponding measurement accuracy for the proposed transverse load sensor, by controlling the semiconductor optical amplifier's injection current in the range of 154 to 419 mA.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.158-165
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• 1994

A fiber optic voltage sensor is demonstrated with a new signal processing scheme that displays the magnitude and the waveform of applied voltage with immunity from the signal frequency change. The sensor is based on a Mach-Zehnder interferometer with a PZT phase modulator as a sensing element. We observed a linear relationship between applied voltage and the number of fringe shift during a half cycle of the ac signal. The temperature dependence of the sensor output is experimentally evaluated over the temperature range from $-20^{\circ}C to 80^{\circ}C$. It is demonstrated that the detrimental polarization modulation effect can be overcome by using polarization maintaining fibers or a half-wave plate. plate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.7
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• pp.557-564
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• 1998

A low loss x-cut $LiNbO_3$optical waveguide was fabricated by Yi in-diffusion, and the properties of guided-mode and the total insertion loss of the pigtailed waveguide with polarization maintaining fiber(PMF) were measured at optical wavelength 1550nm. for forming the waveguides, the parameters of diffusion, Ti thickness, waveguide line-width, length, diffusion temperature, time and atmosphere were set $1400{\AA}$, $8{\mu}m$, 3.3cm, $1050^{\circ}C$, 8 hours and wet bubbled oxygen, respectively. And then after the polishing and piatailing, it showed that the total insertion loss was -4.1dB for TM mode, -5.5dB for TE mode, and mode size, that is, the horizontal/ vertical size were $13.8{\mu}m/18{\mu}m$ for TM mode, $9.6{\mu}m/6.5{\mu}m$ for TE mode.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.567-574
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• 2016

We propose a highly birefringent and dispersion compensating photonic crystal fiber based on a double line defect core. Using a finite element method (FEM) with a perfectly matched layer (PML), it is demonstrated that it is possible to obtain broadband large negative dispersion of about -400 to -427 ps/(nm.km) covering all optical communication bands (from O to U band) and to achieve the dispersion coefficient of -425 ps/(nm.km) at 1.55μm. In addition, the highest birefringence of the proposed PCF at 1.55 μm is 1.92 × 10^-2 and the value of birefringence from the wavelength of 1.26 to 1.8 μm (covering O to U bands) is about 1.8 × 10^-2 to 1.92 × 10^-2. It is confirmed that from the simulation results, the confinement loss of the proposed PCF is always less than 10^-3 dB/km at 1.55 μm with seven fiber rings of air holes in the cladding.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.303-303
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.232-233
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• 2000

초단펄스를 생성하는 방법에는 이득 스위칭, 광 변조기, 모드록킹 레이저 등이 있다. 이중에서 모드록킹 광섬유 레이저를 이용한 초단펄스를 발생시키는 방법은 비용이 많이 들고 부피가 큰 단점을 갖고 있지만, 매우 짧은 펄스 폭 생성, 고 출력의 펄스생성, 그리고, 파장 및 주파수를 조절을 할 수 있다는 장점을 갖고 있다. 한편, 모드록킹 방법에는 수동형과 능동형이 있다. 수동형 방법은 아주 짧은 펄스 폭을 갖는 펄스를 발생할 수 있지만, 출력이 불안정하고 펄스의 발생주기를 조절하기 어려운 반면, 능동형 방법은 상대적으로 펄스폭은 넓지만, 안정된 출력과 펄스 발생주기를 짧게 할 수 있다. 따라서, 고 반복률의 안정된 펄스를 사용하는 초정밀 광 계측기나 광통신에 사용되는 광원으로 능동형 모드록킹 광섬유 레이저가 많이 사용되어지고 있다. (중략)