Characterization of the response of fibre Bragg gratings fabricated in stress and geometrically induced high birefringence fibres to temperature and transverse load

Abstract

The transverse load and temperature sensitivities of fibre Bragg gratings (FBG) fabricated in a range of commercially available stress and geometrically induced high birefringent (HiBi) fibres have been experimentally investigated. The wavelength reflected by the FBG in each polarisation eigenmode was measured independently and simultaneously using a custom designed interrogation system. The highest transverse load sensitivity, of 0.23 ±0.02 nm/(N/mm), was obtained with HiBi FBGs fabricated in elliptically clad fibre. This was ~25% higher than for any other HiBi fibre, which, coupled with the small diameter of the fibre, makes it a good candidate for an embedded or surface mounted strain sensor. The highest temperature sensitivity of 16.5 ± 0.1 pm/ 0 C, approximately 27% greater than any other fibre type, was obtained with the HiBi FBG fabricated in Panda fibre. HiBi FBG sensors fabricated in D-clad fibre were the only ones to exhibit identical temperature sensitivities for the slow and fast axes (11.5 ± 0.1 pm/ 0 C).

Feasibility study on measuring axial and transverse stress/strain components in composite materials using Bragg sensors

“…This was observed for all examined samples. The difference is in the range of 0.4 pm/°C and is comparable to the difference observed in [6].…”

“…It should be noted that the temperature sensitivities from the K-matrix derived from [6] only showed a small difference ( x =15.0 pm/°C and y =15.7 pm/°C). Nevertheless, the derived accuracies are pretty satisfactory.…”

“…For the K-matrix, the values were derived from [6], where the different sensitivities of a Bow-Tie fibre sample were derived. The condition numbers are presented in Table 1 and they indeed increase for decreasing degrees of isolation.…”

Optical temperature sensing on flexible polymer foils

“…Additionally, an increase in temperature sensitivity for stress-induced birefringent fibers has been reported in the literature [111], although the origin of this temperature sensitivity increase stays unexplored until now. Therefore, frozen stress in the fabricated structures, caused by the thermal processing of the foils, can possibly be responsible for the sensitivity increase.…”

All-Fiber Loading Sensor Based on a Hybrid 45° and 81° Tilted Fiber Grating Structure

“…Transverse load sensors based on fiber Bragg gratings (FBGs) and long period gratings (LPGs) made in low-birefringence, hi-birefringence and multi-core fiber have been reported [1][2][3][4]. To function as loading sensors, the majority of these gratings exhibited a pronounced polarization mode split effect resulting from the birefringence induced by the transverse loading.…”