Analysis on the strain and temperature dependence of stimulated Brillouin scattering in a PANDA-type few-mode fiber

Few-mode fibers (FMFs) have potential to overcome the limitations of single-mode fibers (SMFs) in sensing applications, enabling multi-parameter measurement capabilities. PANDA-type FMFs, with polarization-maintaining and higher-order mode support, are particularly well-suited for distributed strain and temperature sensing. This study involves the experimental investigation of intra- and intermodal Brillouin gain spectra (BGS) in PANDA-FMFs, with a focus on their strain and temperature dependencies. Brillouin optical correlation-domain analysis (BOCDA), enhanced by low-frequency differential measurement and far-field detection, effectively suppresses modal interferences and enables peak-by-peak investigation of multipeak BGS. Experimental results show that the strain dependence ranges from 0.0448 to 0.0456 MHz/ε, and the temperature dependence spans 0.998 to 1.106 MHz/°C.