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A kind of magnetic field sensor is proposed, which is based on symmetrically side-polished photonic crystal fiber (PCF) with regular hexagonal air holes. Magnetic fluid (MF) is used as the magnetic field-sensitive material. The polished surfaces are coated with an indium tin oxide (ITO) film to generate lossy mode resonance (LMR) for magnetic field sensing. The obtained magnetic field sensitivity is 466.81 pm/Oe, which can be further adjusted by changing the thickness of the ITO film. The comprehensive sensing performance is evaluated by defining the figure of merit (FOM). The proposed structure is simple and has the capability of mass production, which has great development space in the future. [ABSTRACT FROM AUTHOR]

A kind of novel and compact magnetic field sensor has been proposed and investigated experimentally. The proposed sensor consists of a tapered single mode fiber coupled with a nanostructured magnetic fluid-infiltrated photonic crystal fiber, which is easy to be fabricated. The response of magnetic fluid to magnetic field is used to measure the intensity of magnetic field via whispering gallery mode. The magnetic field-dependent shift in resonance wavelength is observed. The maximum magnetic field intensity sensitivity is 53 pm/mT. The sensor sensitivity is inversely proportional to the thickness of the photonic crystal fiber cladding. [ABSTRACT FROM AUTHOR]

• Magnetic field and temperature sensing are realized with no core fiber coated with magnetic fluid and polydimethylsiloxane. • High sensitivity is obtained with the gold-clad no core fiber probe. • Reflection-like probe is convenient for magnetic field and temperature detection in narrow space. A kind of reflection-type magnetic field and temperature dual-parameter sensor based on surface plasmon resonance (SPR) effect was proposed and investigated. The sensing probe was fabricated with a section of no-core fiber, which was evenly divided into two parts. One part was immersed in magnetic fluid (MF) for magnetic field sensing (Channel 1, referred as CH1). The other part was coated with polydimethylsiloxane (PDMS) for temperature sensing (Channel 2, referred as CH2). The issue of magnetic field and temperature cross-sensitivity was resolved ingeniously. In the magnetic field intensity range of 0–55.1 mT, the maximum magnetic field sensitivity of 122.67 pm/mT was obtained. In the temperature range of 30–70 ℃, the maximum temperature sensitivity was 1662.64 pm/◦C. The sensor has the advantages of simple structure, small size, and potentials for applications in narrow space. [ABSTRACT FROM AUTHOR]

A compact all-fiber magnetic field sensor is achieved by using Mach–Zehnder interferometer based on the hollow optical fiber (HOF) and the magnetic fluid (MF). The HOF is sandwiched between two single mode fibers (SMFs), which form an SMF-HOF-SMF (SHS) structure. Then, the SHS structure is immersed in MF to sense the magnetic field strength. The magnetic field assisted tunable refractive index of MF is exploited to realize the sensor. As a result, the magnetic field strength can be obtained by monitoring the wavelength shift of the SHS structure. The maximum magnetic field sensing sensitivity of −170 pm/Oe is obtained at the wavelength around 1580 nm. Besides, an intensity sensitivity of −0.21268 dB/Oe is also achieved. [ABSTRACT FROM PUBLISHER]

• Magnetic fluids can be easily integrated with optical fiber. • The sensing structure made of microfiber coupler has a large evanescent field. • At the dispersion turning point, the theoretical sensitivity can be infinite. • The problem of high sensitivity but narrow detection range can be solved. A kind of ultrasensitive magnetic field sensor based on microfiber coupler and magnetic fluid (MF) is proposed and investigated. As the working wavelength is near the birefringence-induced dispersion turning point (B-DTP), the sensitivity has been enhanced considerably and the maximum sensitivity can achieve −97.856 nm/mT. By tracking the B-DTP, the problem of high sensitivity but narrow detection range can be solved. The temperature sensitivity of the structure is 0.816 nm/℃. The proposed sensor has the advantages of extremely high sensitivity, which has the potential applications in high-precision magnetic field measurement. [ABSTRACT FROM AUTHOR]