A Tunable Polarization Beam Splitter Based on Magnetic Fluids-Filled Dual-Core Photonic Crystal Fiber

Abstract

A tunable polarization beam splitter (PBS) is proposed based on a dual-core photonic crystal fiber (DCPCF). The DCPCF is filled with magnetic fluids in the air holes, whose refractive index varies with the magnetic field strength. The two polarized modes are separated into the two cores at the output ports in a magnetic-free condition. When magnetic field is applied, the output intensities of the two polarized modes would fluctuate. The polarized modes can be ported out with arbitrary proportion by adjusting the magnetic field intensity. Moreover, the polarized mode would be completely converted at some magnetic field strength. The properties of the DCPCF are investigated by the finite element method (FEM), including mode-conversion magnetic field strength, extinction ratio, fabrication tolerance of the PBS, and the performance of PBS at various temperatures. The numerical results show that at 1550-nm wavelength, the length of the tunable PBS is 8.13 mm. The polarized mode converts at a magnetic intensity of 25 mT with a high extinction ratio greater than -100 dB. In addition, the tunable PBS sustains a fabrication tolerance of at least 0.5% and works well at temperatures in the range of 0-55 °C by adjusting the magnetic field strength.