Wide-range strain sensor based on Brillouin frequency and linewidth in an As₂Se₃-PMMA hybrid microfiber

We propose a wide-range strain sensor based on Brillouin frequency and linewidth in a 50 cm-long As₂Se₃-polymethyl methacrylate (As₂Se₃-PMMA) hybrid microfiber with a core diameter of 2.5 µm. The distributed information over the hybrid microfiber is measured by a Brillouin optical time-domain analysis (BOTDA) system. The wide dynamic range strain from 0 to 15000 µɛ is enabled by measuring the Brillouin frequency and linewidth due to the low Young's modulus of As₂Se₃ core and the high mechanical strength of PMMA cladding. The deformation of the As₂Se₃-PMMA hybrid microfiber is observed when the strain is greater than 1500 µɛ by measuring the distributed Brillouin frequency and Brillouin linewidth over the 50 cm-long hybrid microfiber. The measured errors based on the Brillouin frequency in the range of 0-1500 µɛ and 1500-15000 µɛ are 42 µɛ and 105 µɛ, respectively. The measured error based on the Brillouin linewidth is 65 µɛ at 0-1500 µɛ and the maximum error is 353 µɛ when the tensile strain is 15000 µɛ. No strain memory effect is observed compared with the polymer optical fiber due to Young's modulus in As₂Se₃ is larger than that in polymer. Numerical simulations are developed to accurately predict the strain dependence of Brillouin frequency in the As₂Se₃-PMMA hybrid microfiber.