Journals >Chinese Journal of Lasers
Aiming at the crosstalk of temperature and strain existing in the fiber Bragg grating (FBG) sensor, we use a femtosecond laser and a phase mask to fabricate FBGs in the melting point of two heterogeneous fibers. Because temperature or strain response parameters of the FBGs are different, the simultaneous measurements of temperature and strain can be realized. Temperature and strain response parameters of two kinds of FBGs, including Yb 3+doped fiber with SMF-28 fiber FBGs and Er∶Yb doped fiber with SMF-28 fiber FBGs, are measured, respectively. The results indicate that the Er∶Yb doped FBG has a great difference on temperature response parameter but a similar strain response parameter with the SMF-28 fiber FBG, so the Er∶Yb doped fiber with SMF-28 fiber FBGs can be used to realize the simultaneous sensing on temperature and strain measurement. After annealing at 800 ℃, the reflectivity of Er∶Yb doped fiber FBG with SMF-28 fiber FBG can maintain a long-term stability at 700 ℃. It can be used to realize the temperature-strain dual-parameter demodulation below 700 ℃.
.Aimed at eliminating the fluorescence interference from containers of the sample in the detection of Raman spectroscopy, a dual-axis confocal detection scheme is proposed based on the characteristic that the fluorescence generated by the container and the Raman signal of the sample are not confocal. The experimental results show that the fluorescence interference signals from the container are reduced by an order of magnitude,and the intensity of Raman signal decreases by about 30%. The dual-axis confocal Raman detection scheme can solve the mixed reception problem of Raman signal and fluorescence in the conventional coaxial confocal Raman detection scheme, solve the limitation of the dynamic detection range of Raman signal caused by the fluorescence interference, and achieve the effective detection of Raman signal of the material in fluorescent material containers.
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