Sensitivity Enhancement by Etching Helical-Core Fibers Towards the Dispersion Turning Point

Helical-core fibers have been widely utilized for various applications such as orbital angular momentum manipulation, optical filtering, and sensing. In this work, we demonstrate the sensitivity enhancement of a helical-core fiber by tailoring the resonance wavelength towards the dispersion turning point (DTP) utilizing a post chemical etching process. The responses of the device on external parameters, including mechanical torsion, temperature, strain, and external refractive index, are investigated and compared. When the resonance is close to the DTP, the measured sensitivities with maximal magnitudes reach-321.57nm . mm/rad, 177.51 pm/degrees C, -1.27 pm/mu epsilon, and 131.97 nm/refractive-index-unit for measuring the mechanical torsion, temperature, strain, and external refractive index respectively. The sensitivity magnitudes of torsion, temperature, and strain are enhanced by 7.93, 3.47, and 8.47 times respectively than that of the helical-core fiber without etching. Our work on the knowledge of modifying the resonance spectrum of the helical-core fibers provides an avenue for improving the sensing performance of optical devices.

Automated summary

In this study, the sensitivity of a helical-core fiber was enhanced by tailoring the resonance wavelength using chemical etching. The measured sensitivities for mechanical torsion, temperature, strain, and external refractive index were significantly increased when the resonance was close to the dispersion turning point. The sensitivity magnitudes of torsion, temperature, and strain were enhanced by 7.93, 3.47, and 8.47 times, respectively, compared to the helical-core fiber without etching. This research provides a method for improving the sensing performance of optical devices.