Fiber Laser-Type Current Sensing System Based on Pre-Biased Yttrium Iron Garnet Probe

A fiber laser-type current sensing system based on a pre-biased yttrium iron garnet (YIG) probe is proposed and demonstrated. The fiber laser is composed of an erbium-doped fiber (EDF), a fiber Bragg grating (FBG), and a plane mirror. To transduce the external current variations, a YIG probe is strategically employed within the resonant cavity, proximal to the planar mirror, where the magnetic-optical phase shift caused by current variations modifies the phase difference between two orthogonal light waves, resulting in a shift in the polarization mode beat frequency (PMBF) produced by orthogonally polarized light, which exhibits a direct and measurable correlation to the variations in the current. Especially, a biased magnetic field to the YIG probe resolves the nonlinearity problem. The experimental results demonstrate that when a pre-biased magnetic field of 15 mT is applied to the YIG, the system exhibits sensitivities of 405.36 kHz/A at 11.125 MHz and 392.86 kHz/A at 796.3 MHz, with corresponding R-squared values of 0.99963 and 0.99802, respectively. Furthermore, the maximum sensitivity is increased to 661.1 kHz/A by lowering intrinsic polarization to 3.44 MHz. It provides a reliable new option for the upgrading of current detection technology in related fields.