Abstract

We propose and demonstrate an approach for temperature-sensitivity enhancement based on effective group-velocity matching between the even and odd modes of a dual-core As₂Se₃-PMMA fiber taper on which an antisymmetric long-period grating is inscribed. The transmission of optical pulses in the dual-core As₂Se₃-PMMA taper inscribes the antisymmetric long-period grating that causes the electric fields to couple back and forth between the even and odd modes leading to effective group-velocity matching between the two modes. The variation of the difference between phases of the two modes ϕd(λ) with respect to wavelength tends to 0 (∂ϕd(λ)/∂λ → 0) near the resonance wavelength of the grating due to effective group-velocity matching between the two modes, and consequently, thermally induced change of the difference between phases of the two modes ϕd(λ) leads to a large wavelength shift indicating enhancement of the temperature measurement sensitivity. Experimental results show that temperature measurement sensitivity in the wavelength range with effective group velocity matching is enhanced by a factor of 4.0 in comparison with the sensitivity in the wavelength range that does not have effective group velocity matching in the dual-core taper with As₂Se₃ core diameter of 1.5 μm. Exploiting sensitivity enhancement within the group-velocity matching wavelength range opens the path toward the realization of novel high-sensitivity fiber sensors for temperature and strain measurement.

© 2018 IEEE

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