Simultaneous Measurement of Magnetic Field and Temperature Based on Magnetic Fluid-Infiltrated Photonic Crystal Cavity

Abstract

A method for simultaneous measurement of magnetic field and temperature with high sensitivity and high precision was realized according to magnetic fluid (MF)-infiltrated photonic crystal cavity, where two different types of MF were, respectively, infiltrated into certain air holes adjacent to a waveguide to form two cascaded cavities. As the refractive index (RI) of MF is dependent on external magnetic field and temperature, the two independent resonant dips of cascaded cavities that can be simultaneously monitored at the output spectrum of the waveguide would all shift with the change of external magnetic field or temperature. Using finite-difference time-domain method, the RI sensitivity of the proposed cavity was firstly analyzed and optimized, and then the linear relationships between the shifts of two resonant wavelengths and external magnetic field/temperature were calculated. Finally, combined with the dual-wavelength matrix method, the magnetic field detection limit could reach to 1.333 × 10 −4 T with the uncertainty of ±0.22 × 10 −4 T (coverage factor k = 2) and detection range from 0 to 0.06 T. Simultaneously, the temperature detection limit could reach to 0.301 K with the uncertainty of ±0.051 K (k = 2) and detection range from 250 to 340 K.Index Terms-Magnetic field, magnetic fluid (MF), photonic crystal cavity, simultaneous measurement, temperature.

A Photonic Crystal Magnetic Field Sensor Using a Shoulder-Coupled Resonant Cavity Infiltrated with Magnetic Fluid

“…The resonant wavelength of the PC cavity is highly sensitive to the effective refractive index (RI) of the cavity defect. When the RI of the PC cavity varies slightly, a measurable resonant wavelength shift can be detected [36,37]. In this work, a kind of PC magnetic field sensor based on shoulder-coupled cavity infiltrated with MF is proposed.…”