Intensity-modulated rotation angle sensor based on multi-core fibers

An intensity-modulated rotation angle sensor based on eccentric dual-core fiber (EDCF) and seven-core fiber (SCF) is proposed and demonstrated. The sensor configuration comprises an EDCF and a cascaded fan-out SCF. Input light is coupled from the eccentric core of the EDCF into the outer cores of the SCF for transmission. The output light intensities from the seven single-mode fibers (SMFs) of the fan-out are detected by photodiodes to quantify the optical power in each core of the SCF. Both simulation and experimental results verify a correlation between the light intensity distributions in the outer cores of the SCF and the rotational angle of the EDCF. Lorentzian fitting is applied to the intensity profiles of the six surrounding cores of the SCF at each angular position. By extracting the peak horizontal coordinates from these fittings, a linear relationship is established between these coordinates and the rotation angle. The sensor achieves full 360° angular coverage with a resolution of 10° and a sensitivity of 0.0168 core number/°. Featuring a simple structure and wide measurement range, this sensor exhibits significant potential for applications in industrial automation and full-range angle monitoring scenarios.