Fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity for magnetic field vector detection

Abstract

A fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity is proposed for wide-bandwidth magnetic field vector detection. The probe is constructed with the multimode fiber in which the end-surface is integrated with the Fe3O4@C colloidal nanoparticles by a silicone tube. The colloidal nanoparticles form a three-dimensional photonic crystal structure by magnetic field for diffraction selectivity. The lattice constant and diffraction angle are adjusted by the intensity and direction of the magnetic field, respectively. Obtaining the directional diffraction light through the magnetic field-induced photonic band gap shift with the wavelength blue shift and reflectivity change is confirmed by theory and experiment. The results show that the maximum sensitivity reaches up to 19.7 nm/mT in response range from 13 mT to 200 mT. For vector detection, the peak wavelength shift from 740 nm to 485 nm and reflectance shift from 71% to 7% covering the 0–45° region is verified. In addition, the proposed method could decouple intensity and direction of the magnetic field completely. The fiber optic probe integrated with colloidal nanoparticles has wide detection range and high sensitivity with rapid response. It will open up new horizons for inspiring design and application of magnetic field vector detection in robot posture control and motion perception.