Demonstration of gain multiplication by series assembly of fiber-optic cantilever beam deflection: Measurement of low magnetic field and magnetization of probe samples

We report our experimental realization of fiber-cantilever beam-deflection magnetometer using a series assembly of deflecting fiber-cantilevers for measuring low magnetic field (∼mT) and magnetization of probe nano-particles. Using single-mode fibers coated with optimized cobalt-doped-nickel-ferrite nano-particles, we devise a concatenated twin-fiber-cantilever assembly that identically modulate transmitted fiber-exit beam with varying external magnetic field. We measure surrounding field as low as ∼1 mT and demonstrate gain-multiplication through series-fed signal of fiber-cantilever response. Our cantilever-deflection-transmission analysis is devised to interpret the experimental observation and to determine magnetization of probe-samples. A Sagnac-loop assisted cantilever arrangement is also fabricated and tested that yielded the same sensitivity.