Magneto-Modulating Polarization Converter Based on a Dual-Core Photonic Crystal Fiber

A magneto-modulating polarization converter (PC) based on a new type dual-core photonic crystal fiber (DCPCF) is proposed and analyzed. In DCPCF, the two cores are surrounded by a central circular air hole and two lateral elliptical air holes in the horizontal axis. The central air hole is filled with magnetic fluids (MF). Without external magnetic field, DCPCF acts as a simple polarization splitter. When magnetic field applied, due to the refractive index of MF varying with the magnetic field magnitude, the intensities of the two polarization modes would interchange alternately. At a certain magnetic field, the two polarization modes would rotate 90° at the output ports. In this case, a magneto-modulating PC is realized. The performance of the PC is analyzed by the finite element method. The simulation results show that the length of the PC is 1007 μm. The polarization mode conversion can be realized at a magnetic field magnitude of 40.5 mT with a room temperature 21°C. A high extinction ratio greater than 70 dB is obtained for mode-conversion around 1550 nm wavelength. In addition, the PC works well in the temperature range from 0°C to 60°C by regulating the magnetic field magnitude. The optical fiber-based PC eliminates the silicon-on-insulator circuit chip, which can be integrated with optical system easily and conveniently.