Browsing by Author "Yeh, C.-H."

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S-Band long-distance fiber Bragg grating sensor system
(2007-04-01)
Yeh, C.-H.
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Lin, M.-C.
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Cheng, B.-C.
;
Chi, S.
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光電工程學系
We propose and investigate experimentally a sigma fiber laser scheme, which uses multiple fiber Bragg grating (FBG) sensors as the feedback elements, for a long-distance sensor system with 20-km long in S-band at first. By tuning a wavelength selective filter located in a laser cavity over the gain bandwidth, the laser selectively lases at each of the fiber Bragg wavelengths of the sensors, thus allowing strain-induced shifts in the Bragg wavelengths to be monitored. In our experiment, an S-band four-sensor system is proposed and investigated experimentally. (c) 2007 Elsevier Inc. All rights reserved.
Unitizations of double-ring structure and Erbium-doped waveguide amplifier for stable and tunable fiber laser
(2007-05-01)
Chou, S.-Y.
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Yeh, C.-H.
;
Chi, S.
;
光電工程學系
;
Department of Photonics
We propose and demonstrate experimentally a single longitudinal-mode (SLM) fiber double-ring laser using an Erbium-doped waveguide amplifier (EDWA), polarization controller (PC), and a fiber Fabry-Perot tunable filter (FFP-TF) into the ring cavity. In addition the output power side mode suppression ratio (SMSR), and the stabilities of power and wavelength of the laser also are investigated.
Using ring-filter and saturable-absorber-based filter for stable erbium fiber laser
(2007-07-01)
Yeh, C.-H.
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Chen, C.-T.
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Lee, C.-N.
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Shih, F.-Y.
;
Chi, S.
A stable single-frequency dual-coupler ring (DCR) laser is proposed that operates in a single mode for more than an hour by an incorporating unpumped erbium-doped fiber (EDF) as a saturable-absorber filter and optimizing the length of the EDF used as gain medium. The proposed fiber laser doesn't use any fiber Bragg gratings or etalon filters into intracavity to lase a single-frequency. This laser has an optical signal to noise ratio (OSNR) of > 60 dB at 1562.9 nm. In addition, the stabilities of the output power and wavelength have also been studied.
Utilizations of EDFA and SOA in series for broadband gain amplification
(2007-06-01)
Yeh, C.-H.
;
Chi, S.
;
光電工程學系
;
Department of Photonics
A broadband hybrid two-stage fiber amplifier module, constructed of an erbium-doped fiber amplifier (EDFA) and a semiconductor optical ampler (SOA) in series, is proposed and investigated experimentally. IN the proposed amplifier, a short length erbium-doped fiber (EDF) was use din first stage for the pre-amplifier to increase the gain and reduce the noise figure. Therefore, the proposed hybrid amplifier not only enhances gain value, but decreases the noise figure. Moreover, the proposed ampler can achieve 110 nm amplification bandwidth between 1500 and 1610 nm, when the entire gain are large than 11 dB and noise figure are less than 8 dB for -25 dBm input saturation power. Moreover, the performance of gain and noise figure in the proposed fiber amplifier has also been discussed.