3×3 Microfiber Coupler Simulation and RI Sensing Performance with Output end Sagnac Loop

An optical fiber 3×3 microfiber coupler (MFC) is fabricated by fusing taper method. The working principle of the MFC is theoretically analyzed, the optical field of the MFC with different coupling degrees is theoretically simulated. The liquid refractive index (RI) sensing performance of the MFC with output Sagnac loop is experimentally studied, and its highest sensitivity is 25108nm/RIU. Theoretical and experimental results show that the wavelength has tunable characteristics, which can be used in tunable filters and wavelength division multiplexers, and the sensing characteristics have potential applications in biomedical diagnosis, environmental monitoring, food safety monitoring, and other fields.