• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.9-10
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• 2006

We report the realization of the Yb/Tm co-doped silica glass optical fiber amplifier operating at 1470 nm upon 980 nm pumping. The energy transfer coefficient from Yb to Tm was estimated using the threshold condition of the optical amplifier.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.238-239
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• 2000

The optical fibers are an interesting medium for effective tunable optical frequency conversion in the spectral range of UV, Visible, and near-IR through the nonlinear processes. A number of papers for developing the wideband and flat-gain amplifier for the WDM system applications through the combination of EDFA or thulium-doped fluoride fiber amplifier and Raman amplifier, are reported$^{(1)}$ . Even though a variety of papers related to Raman amplifications are published, the amplification with the feedback of the residual pump is not investigated yet. Accordingly, in this paper, we report the characteristics of forward Raman amplification by the simple and double-pass fiber Raman configuration through the feedback of residual pump beam. (omitted)

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.357-361
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• 2013

A regenerative Er-doped fiber amplifier system for a high-repetition-rate optical pulse train is investigated for the first time. A signal pulse train with a wavelength tuning range of 18 nm is produced by a passive mode-locked fiber laser based on a nonlinear polarization rotation technique. In order to realize the amplification, an optical delay-line is used to achieve time match between the pulses' interval and the period of pulse running through the regenerative amplifier. The 16 dB gain is obtained for an input pulse train with a launching power of -30.4 dBm, a center wavelength of 1563.4 nm and a repetition rate of 15.3 MHz. The output properties of signal pulses with different center wavelengths are also discussed. The pulse amplification is found to be different from the regenerative amplification system for CW signals.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.291-297
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• 1994

A feedback loop with bandpass filter is introduced in erbium-doped fiber amplifier to clamp the amplifier gain by lasing the amplifier at a selected wavelength. The gain and the ASE (amplified spontaneous emission) output spectra are found to be independent of input signal power and pump power variation so long as the amplifier is lasing. Also they are found to be dependent only on the overall loss of the feedback loop. Even in the case of slowly modulated large signal input, signal distortion due to gain saturation is not observed.served.

• Journal of IKEEE
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• v.13 no.4
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• pp.103-109
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• 2009

We report an efficient jitter reduction technique in an analog fier-optic link employing a Mach-Zehnder modulator followed by an erbium-doped fiber amplifier. By adjusting the modulator-bias to $0.089V_{\pi}$, we could increase the RF gain up to 10.65 dB for 10 GHz RF signal and reduce the random jitter by 46.5%, max, at an input optical power of -0.11 dBm to the EDFA.

• Korean Journal of Optics and Photonics
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• v.29 no.4
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• pp.159-165
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• 2018

In this paper, we report on the high power amplification of a narrow-linewidth Yb-doped polarization-maintained (PM) fiber laser in a 3-stage, all-fiber master oscillator power amplifier (MOPA) system. The linearly polarized single-mode output power was 400 W with an 85% slope efficiency, with a linewidth of 2.5 GHz (full width at half maximum). Furthermore, mitigation of mode instability (MI) has been demonstrated by tightly coiling the gain fiber to a diameter of 11 cm. In addition, methods for higher power scaling are discussed.

• ETRI Journal
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• v.27 no.4
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• pp.411-417
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• 2005

$Pr^{3+}-doped$ selenide glass optical fiber, which guarantees single-mode propagation of above at least 1310 nm, has been successfully fabricated using a Ge-Ga-Sb-Se glass system. Thermal properties such as glass transition temperature and viscosity of the glasses have been analyzed to find optimum conditions for fiber drawing. Attenuation loss incorporating the effects of an electronic band gap transition, Rayleigh scattering, and multiphonon absorption has also been theoretically estimated for the Ge-Ga-Sb-Se fiber. A conventional double crucible technique has been applied to fabricate the selenide fiber. The background loss of the fiber was estimated to be approximately 0.64 dB/m at 1650 nm, which can be considered fairly good. When excited at approximately 1470 nm, $Pr^{3+}-doped$ selenide fiber resulted in amplified spontaneous emission and saturation behavior with increasing pump power in a U-band wavelength range of 1625 to 1675 nm.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.118-123
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• 2014

For multi parameter optimization of Raman Fiber Amplifier (RFA), a simple genetic algorithm is presented in the scenario of a 320 channel Dense Wavelength Division Multiplexed (DWDM) system at channel spacing of 25 GHz. The large average gain (> 22 dB) is observed from optimized RFA with the optimized parameters, such as 39.6 km of Raman length with counter-propagating pumps tuned to 205.5 THz and 211.9 THz at pump powers of 234.3 mW, 677.1 mW respectively. The gain flattening filter (GFF) has also been optimized to further reduce the gain ripple across the frequency range from 190 to 197.975 THz for broadband amplification.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.97-101
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• 1999

We propose and demonstrate a novel sensor which can simultaneously measure strain and temperature. The sensor is composed of a single fiber Bragg grating and an erbium-doped fiber amplifier. Using linear variation in the amplified spontaneous emission power of an erbium-doped fiber amplifier with temperature, we determine the temperature. By subtracting the temperature effect from the Bragg wavelength shift, we determine the strain. Experiments show rms deviations of $18.2{\mu}{\varepsilon}$ and $0.7^{\circ}C$ for strain and temperature, respectively.

• Journal of the Optical Society of Korea
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• v.17 no.3
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• pp.237-241
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• 2013

This paper presents an efficient evolutionary method to optimize the gain ripple of multi-pumps photonic crystal fiber Raman amplifier using the Fuzzy Adaptive Modified PSO (FAMPSO) algorithm. The original PSO has difficulties in premature convergence, performance and the diversity loss in optimization as well as appropriate tuning of its parameters. The feasibility and effectiveness of the proposed hybrid algorithm is demonstrated and results are compared with the PSO algorithm. It is shown that FAMPSO has a high quality solution, superior convergence characteristics and shorter computation time.