Browsing by Author "Liu, Wen-Fung"

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Generation of chirped long-period gratings in photonic crystal fiber using a constant period corrugated device
(2007)
Chen, Hou-Ren
;
Lin, Kuei-Huei
;
Lin, Ja-Hon
;
Liu, Wen-Fung
;
Hsieh, Wen-Feng
Chirped long-period fiber gratings (LPGs) are generated in bended photonic crystal fiber (PCF) by using a constant period corrugated device. As the chirping increases, the rejection bandwidth in the transmission spectra of LPGs also increases. Spectral modulation peaks are observed and the modulation depth is increased with the amount of chirping. A chirped dual LPG with rejection bandwidth of about 300 run has been obtained in a bended PCF.
In-fiber Long-period Grating and Fiber Bragg Grating-based Sensor for Simultaneously Monitoring Remote Temperature and Stress
(2018-01-01)
Chang, Hung-Ying
;
Yeh, Chien-Hung
;
Huang, Chuan-Ying
;
Fu, Ming-Yue
;
Chow, Chi-Wai
In this study, we experimentally demonstrated that a high-sensitivity fiber sensor can be used for the remote sensing of temperature and stress simultaneously. The proposed sensor includes several sensing heads, each of which is composed of a long-period grating (LPG) and a fiber Bragg grating (FBG). Moreover, the optical characteristics of both the FBG and LPG are different. On the basis of these different optical features and the sensing transfer matrix, temperature and stress can both be remotely measured simultaneously. The temperature sensitivities of the grating-wavelength shift and grating-reflection intensity are about 0.0082 nm/degrees C and 0.044 dBm/degrees C, respectively. The strain sensitivities of the grating wavelength shift and grating-reflection intensity are respectively around 0.0133 nm/g and 0.0089 dBm/g. Therefore, the fiber sensor can provide a simple method with excellent sensitivity for applications of structure-security monitoring and industrial engineering measurements.
Smart architecture for stable multipoint fiber Bragg grating sensor system
(2017-12-01)
Yeh, Chien-Hung
;
Tsai, Ning
;
Zhuang, Yuan-Hong
;
Huang, Tzu-Jung
;
Chow, Chi-Wai
In this work, we propose and investigate an intelligent fiber Bragg grating (FBG)-based sensor system in which the proposed stabilized and wavelength-tunable single-longitudinal-mode erbium-doped fiber laser can improve the sensing accuracy of wavelength-division-multiplexing multiple FBG sensors in a longer fiber transmission distance. Moreover, we also demonstrate the proposed sensor architecture to enhance the FBG capacity for sensing strain and temperature, simultaneously.