研究目的
Investigate and characterize distributed Brillouin sensors based on the intra- and intermodal stimulated Brillouin scattering (SBS) of the LP01 and LP11 guided modes in an elliptical-core two-mode fiber (e-core TMF).
研究成果
The e-core TMF provides a robust platform for distributed Brillouin sensors, with strain and temperature coefficients of νB in the intra- and intermodal SBS very close to each other, showing a discrepancy less than 1%. The intermodal BOTDA system can simultaneously measure the distribution of νB and the propagation loss of the LP11 mode. The double-peak BGS in the intramodal SBS of the LP11 mode can be accurately analyzed using BOCDA with a differential measurement scheme.
研究不足
The study is limited by the spectral proximity of the two peaks in the intramodal SBS of the LP11 mode, which complicates accurate analysis in distributed measurements. Additionally, the bending loss measurement accuracy is limited by the practical application of bending without adjusting the bending orientation.
1:Experimental Design and Method Selection:
The study involves measuring the strain and temperature dependence of the Brillouin frequency (νB) for each intra- and intermodal SBS in an e-core TMF. Techniques such as Brillouin optical time-domain analysis (BOTDA) and Brillouin optical correlation domain analysis (BOCDA) with a differential measurement scheme are employed.
2:Sample Selection and Data Sources:
An elliptical-core two-mode fiber (e-core TMF) with a core diameter of
3:8 μm × 2 μm and a Δ of 6% is used. List of Experimental Equipment and Materials:
Equipment includes a distributed feedback laser diode (DFB-LD), electro-optic modulator (EOM), microwave generator (MWG), fiber Bragg grating (FBG), polarization switch (PSW), variable optical attenuator (VOA), photo detector (PD), and mode-selective coupler (MSC).
4:Experimental Procedures and Operational Workflow:
The pump and probe waves are modulated and launched into the fiber under test (FUT) in specific modes. The Brillouin gain spectrum (BGS) is measured under varying strain and temperature conditions.
5:Data Analysis Methods:
The BGS is analyzed to determine the strain and temperature coefficients of νB for each SBS type.
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