Feasibility study of employing mechanically induced long-period fibre grating as optical-based sensors

Abstract

The investigation of long-period fibre gratings formed by a 3D printer with several grating periods is presented here. The proposed grating device was pressed on to an optical fibre to observe the resonant wavelengths as a function of different groove periods. Results showed that devices with 700 and 800 nm grating period introduced resonant wavelengths of 1,487 and 1,570 nm with refractive index changes of 2.121 × 10⁻³ and 1.963 × 10⁻³, respectively. Once resonant wavelengths were known, an optical time domain reflectometer (OTDR) was employed to determine light behaviour, event positions, and losses. The OTDR trace revealed that the non-reflective event occurred at the grating perturbation position. Consequently, the wavelength-dependent-resonance was caused by the non-contra-directional coupling of light from the fibre core to fibre cladding and its attenuation was a cubic function of an applied force. The proposed approach, therefore, shows a great potential to be used for the sensing applications in the vulnerable environments.

KEYWORDS:

• Mechanically induced long-period fibre grating
• resonant wavelength
• optical sensors

Acknowledgements

Financial support for this study was provided by the Research Strengthening Project of the Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Thailand. The authors would like to thank Yokokawa (Thailand), Ltd. for the generous support of essential equipment for this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).