Simultaneous Measurement of Temperature and Strain in a Dual-Core As2Se3-PMMA Taper

We propose and demonstrate an approach for high-sensitivity simultaneous temperature and strain measurement in a dual-core As
₂
Se
₃
-polymethyl methacrylate (PMMA) taper. High measurement sensitivity is achieved by combining the large thermal-expansion coefficient of the PMMA cladding, the low stiffness of the micrometer diameter As
₂
Se
₃
core, and the large difference between the refractive indices of As
₂
Se
₃
and PMMA. High measurement sensitivities of -115 pm/°C and -4.21 pm/με are measured from the transmission spectrum of one principal polarization axis of the dual-core fiber, and -35.5 pm/°C and -3.16 pm/με are obtained from the transmission spectrum of the second polarization axis of the dualcore fiber. Decorrelation between the temperature and strain measurement sensitivities of the principal polarization axes is achieved through thermally induced squeezing of the As
₂
Se
₃
cores by the PMMA cladding due to an order of magnitude difference between the thermal-expansion coefficients of As
₂
Se
₃
and PMMA, enabling simultaneous measurement of temperature and strain variations with the temperature and strain uncertainty of 0.15°C and 1.87 με.