High-Sensitivity Temperature and Strain Measurement in Dual-Core Hybrid Tapers

We demonstrate an approach for high-sensitivity temperature and strain measurement in a dual-core As₂Se₃PMMA taper with an As₂Se₃ core diameter of 2.5 μm. To improve the sensitivity of temperature and strain measurement, we designed the dual-core As₂Se₃-PMMA fiber with inorganic As₂Se₃ cores and organic PMMA cladding and also the even and odd modes to build an interferometer. The variation of the difference between phases of the two modes with respect to wavelength (∂φd(λ)/∂λ) decreases with the As₂Se₃ core diameter increasing, and consequently, thermally induced and straininduced change of the difference between phases of the two modes φd(λ) leads to a large wavelength shift indicating enhancement of the temperature and strain measurement sensitivity. Furthermore, thermally induced longitudinal and transverse forces on the As₂Se₃ cores further enhance the temperature measurement sensitivity. High sensitivities of 436 pm/°C, -6.23 pm/με and 572 pm/°C, and -3.63 pm/με from the transmission spectra of axis-1 and axis-2 in the dual-core As₂Se₃-PMMA taper are obtained.