Broadband and high-extinction plasmonic polarization filter using photonic crystal fiber with dual elliptical graphene-coated silver layers

Polarization filters are key components driving the widespread adoption of new photonic integration technologies. This work demonstrates a broadband and high-extinction plasmonic polarization filter using photonic crystal fiber with dual graphene-coated elliptical silver layers. The finite element method is employed to analyze in-fiber transmission behavior. The graphene-silver layers are introduced to stimulate the surface plasmon resonance effect, significantly enhancing the difference in signal strength across different polarization directions. The numerical results indicate that when the lattice constant is 1.6 μm, the diameter of the cladding hole is 1.2 μm and the larger diameter of holes near core region is 1.45 μm, the length of elliptical hole long axis is 2.0 μm, the length of elliptical hole short axis is 0.60 μm, the thickness of silver layer is 50 nm, and the thickness of graphene layer is 17 nm, the intensity difference between the two polarization signals reaches 12712 times. The 400 μm-long PCF filter, supporting single mode single polarization transmission, exhibits the maximum extinction ratio of -249.1 dB, with an ultra-broad band of greater than 880 nm, covering two common communication windows of 1.31 and 1.55 μm. Boasting excellent comprehensive performance, this all-fiber polarizer is anticipated to be a candidate device for further optimization of photonic signal processing, optical communication, and optical computing technologies.