Temperature compensated magnetic field sensing using dual S-bend structured optical fiber modal interferometer cascaded with fiber Bragg grating

Abstract

A temperature compensated magnetic field strength optical fiber sensor has been proposed and experimentally demonstrated. A fiber Bragg grating (FBG) is cascaded to modal interferometer (MI), which is fabricated by dual S-bend splicing between thin fiber (TF) and single mode fiber (SMF) with intentionally controlled misalignment between cores. We established a modified numerical model to describe the multi-mode interference of this exceptional S-bend and misalignment structure, together with the simulation based on beam propagation method to gain insight into its operation mechanism. The FBG is used to interrogate the temperature change, and then compensate the perturbation of temperature on transmission of the MI. Thanks to the proposed dual S-bend structure and the diameter-thinned TF used here; we have obtained high magnetic sensitivity of -0.0678 dB/Oe using only 4 mm TF after the elimination of ambient temperature change.

High sensitivity optical fiber liquid level sensor based on a compact MMF-HCF-FBG structure

“…It can be seen that the temperature sensitivities of the MZI and FBG are 0.015 nm °C−1 and 0.009 nm °C−1 , respectively. In the experiment, the method of cascading FBG is used to calibrate and compensate the temperature [24]. The reason for the low temperature sen sitivity of the sensor is that the HCF has a very small thermal optic coefficient and thermal expansion coefficient.…”

A magnetic field sensor based on a dual S-tapered multimode fiber interferometer

“…Magnetic fluids (MFs) is one kind of magneto-optical nano-material constituted by surfactantcoated magnetic nanoparticles suspending in carrier fluids [1]. Under external magnetic fields, MFs would exhibit versatile physical properties, including Faraday and birefringence effect, tunable refractive index, thermal-optical effect, optical anisotropy, and field-dependent transmission, etc [2][3][4][5][6].…”