System design for adopting magnetofluid and LPFG to measure magnetic field and temperature

Abstract

Owing to the insufficient attention to temperature change resulting from the magnetic field sensing scheme of magnetic liquid and long period fiber grating (LPFG), the sensing scheme that measures magnetic field and also the temperature at the same time by using magnetic liquid and two cladding long period fiber gratings with different effective thermal optical coefficient is presented. By measuring the difference of resonance wavelengths between the two long period fiber gratings, the variation of temperature is obtained and then the magnetic field measurement results will be corrected. The relationship between a certain range of temperature variation and the variation of resonance wavelength of long period fiber grating and the magnetic liquid refractive index will be revealed by means of theoretical analysis. System emulation indicates that if the ambient temperature variation is within 14 °C, the maximum relative error of obtained temperature is 1.5% and the precision of magnetic field intensity based on the magnetic field sensing scheme of magnetic liquid and long period fiber grating is at least improved by 70%.