Dual-parameter sensing of temperature and strain realized by two π-PSFBGs cascaded

Abstract

This paper investigates the dual-parameter sensing of temperature and strain using π-phase-shifted fiber Bragg gratings (π-PSFBGs). In many practical engineering applications, temperature and strain are often present simultaneously, which can interfere with each other's sensing. To achieve dual-parameter sensing of temperature and strain, two π-PSFBGs are modified with phase-shifted peaks of 1547 nm and 1550 nm, respectively. The π-PSFBG of 1547 nm is wrapped with a heat shrinkable tube to increase its temperature sensing sensitivity by 185.6%, while its strain sensing sensitivity is reduced by 91.083%. The π-PSFBG of 1550 nm is coated with indium tin oxide (ITO) film using the pulsed laser deposition (PLD) method to increase its temperature sensing sensitivity by 22.3%, while its strain sensing sensitivity is reduced by 16.03%. Finally, the two modified π-PSFBGs are cascaded to realize dual-parameter sensing of temperature and strain. The ITO film coating on the surface and heat shrinkable tube wrapping can reduce the interference of external light on the signal light and protect the fiber grating. By setting the optical spectrum analyzer (OSA) accuracy to 0.02 nm, the sensing information can be extracted by scanning within a few nanometers, and the sharp phase-shifted peak of the π-PSFBG helps accurately locate the signal wavelength. The results demonstrate the potential for the practical application of the proposed dual-parameter sensing method.