Ultrahigh-Sensitive Triple-Parameter Sensor Based on D-Shape Three-Hole Fiber for Simultaneous Detection of Magnetic Field, Temperature, and Relative Humidity

An ultrahigh-sensitive triple-parameter sensor based on D-shaped three-hole fiber (DTHF) is proposed for simultaneous detection of magnetic field, temperature, and relative humidity. The DTHF is constructed by side-polishing one side of three-hole fiber to let one air hole open, and thus, an arc-shaped groove is formed. Through filling the magnetic fluid (MF), polydimethylsiloxane (PDMS) into two different air holes and injecting polyvinyl alcohol (PVA) into the arc-shaped groove, a DTHF-based triple-parameter sensor can be constructed for synchronous detection of magnetic field, temperature, and relative humidity Meanwhile, three Al wires are modified at the positions closest to the fiber core in the arc-shaped groove and two air holes to excite surface plasmon resonance (SPR), which is beneficial to enhance the sensitivity. High sensing performance can be achieved by optimizing the structural parameters of DTHF-based sensor. Numerical results indicate that the DTHF-based triple-parameter sensor can detect the magnetic field in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$35\sim 110$ </tex-math></inline-formula> Oe, temperature in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14.3~^{\circ }$ </tex-math></inline-formula>C<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 64.3~^{\circ }$ </tex-math></inline-formula>C, and relative humidity in the range of 30%~80%. The maximum magnetic field sensitivity, maximum temperature sensitivity, and maximum relative humidity sensitivity are as high as 62 000 pm/mT, 5.0 nm/°C, and 57.8 nm/%RH, respectively. The maximum magnetic field sensitivity and the maximum relative humidity sensitivity are both more than one order of magnitude improvement in comparison to that of single-parameter sensors for magnetic field and relative humidity, while the maximum temperature sensitivity is comparable to that of the single-parameter temperature sensor. The DTHF-based triple-parameter sensor with high integration, low difficulty for analytes filling, and high sensitivities has the potential application in fields of marine resource development and multiparameter environmental monitoring.