Magnetic Field Detection by an SPR Plastic Optical Fiber Sensor and Ferrofluids

Several surface plasmon resonance (SPR) sensors in optical fibers have been presented for the detection of magnetic fields. These SPR sensors measure the variation of the refractive index of a magnetic fluid in contact to the metal film, when the magnetic field changes. In this work, we have presented a different approach to monitor a magnetic field exploiting SPR optical fiber sensors and ferrofluids. More specifically, we have inserted a patch of multimode plastic optical fiber (POF) covered with ferrofluids between a light source and an SPR-POF sensor connected to a spectrometer. The magnetic field in the region near the patch covered by ferrofluids exerts a bending force on the patch changing the light in input to the SPR sensor and modifying the SPR phenomenon, in terms of resonance’s shape and wavelength.