Multi-band polarization switch based on magnetic fluid filled dual-core photonic crystal fiber

Abstract The research of high-performance polarization controllers is of great significance for expanding the application field of polarization optics. Here, a polarization switch is demonstrated by using a dual-core photonic crystal fiber (DCPCF) with four symmetrical air holes, placed above and below each core, filled with magnetic fluid (MF). The switch, which utilizes a magnetic field to change the coupling length ratio of the x and y polarization modes, enables dynamic tuning of the polarization state and extinction ratio. Numerical results show that when the working length is 36.638mm, the magneto-optical polarization switch can operate in four communication bands, i.e., 1509nm to 1520nm, 1544nm to 1556nm, 1578nm to 1591nm, and 1611nm to 1624nm. Moreover, the extinction ratio (ER) is greater than 20dB in the fiber length range of 38.5 mm to 38.7 mm, indicating that the device has a good fault tolerance for the interception of the fiber length.