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Strain measurement based on fixed wavelength transmission of tapered long-period fiber grating

Tang Yong, Zhang Hao, Zhang Li, Yu Xin Feng, Bai Yun Feng

Optica Applicata

2022

Vol. 52, nr 4

511--519

This paper studies the relationship between transmission intensity and strain based on tapered long-period fiber grating at a fixed wavelength. In experiments, tapered long-period fiber grating was prepared by the electric melting method. Experimental results show that two resonance peaks appeared at 1482 and 1537 nm, respectively. Here is the elaboration of the relationship between the resonant wavelength and the strain, its wavelength-strain sensitivity is 20 pm/με, and the linearity was negative. Then our next study was about the relationship between transmission intensity and strain at a fixed wavelength. The results show that the transmission intensity at a fixed wavelength is related to the exponent with strain. The coupled-mode theory is applied to simulate the relationship between fixed wavelength and strain. The simulation results matched the experimental results. Two fixed wavelength transmission intensity ratio was used, and the ratio showed a linear relationship with the strain, and the slope is –0.018 dB/με. Therefore, within the 0.01% resolution of our detector, we could resolve a 0.16 με strain change. We can select the appropriate light source and detector to achieve higher measurement accuracy. Thus, there is a great potential in fiber grating strain sensors.

Holocene activity and seismic hazard analysis of faults in Damxung, Tibet

Yang Gang, Tang Yong, Lei Dongning, Hu Qing, Wu Jianchao

Acta Geophysica

2020

Vol. 68, no. 3

597--604

Based on interpretation of remote sensing and geological feld survey result, three secondary faults are distributed in parallel in Damxung of the southeastern piedmont fault of Nyainqentanglha mountain, which form landform profle across normal faults of graben due to cut platform margin of grade I terrace scarp formation. Through researching the displacements and the collected sediments dates, it is obtained that the horizontal slip rate is about 0.6 mm/a (millimeter per year), and the vertical slip rate is about 1.7 mm/a since 4 ka B.P. (kilo years before present). The northern margin of Damxung basin is a seismic gap, which continuously accumulated strain energy is not released in the M7.5 Damxung earthquake and the M8.0 Yangbajain earthquake. The fracture length of the seismic space can be regarded as the minimum length of potential surface rupture. The maximum moment magnitude of potential earthquakes is at least M6.8.in northern margin of Damxung basin the normal fault magnitude estimation formulas from Wells and Coppersmith (Bull Seismol Soc Am 84(4):974–1002, 1994).