Mid-infrared broadband in-fiber polarization beam splitter based on dual core photonic crystal fiber with dual aluminum wires

Abstract

The polarizing beam splitter (PBS) plays an important role in meeting the growing demand of communication capacity. This paper presents a novel mid-infrared broadband in-fiber PBS using dual-core photonic crystal fiber (DC-PCF) with dual aluminum wires numerically. The high refractive index substrate material As₂S₃ glass can facilitate the extension of the working wavelength to the mid-infrared band, and the aluminum wires provide plasmonic effect to enhance the birefringence of the proposed PCF to promote the compactness of the device. The numerical results demonstrate that the coupling length ratio of 2 can be achieved at 3.3 μm, when the diameter of cladding holes is 1.6 μm, the diameter of central hole is 1.2 μm, the diameter of inner small holes is 0.7 μm, the diameter of aluminum-filled holes is 2.0 μm and lattice constant is 2.1 μm. The aluminum wires have a remarkable tuning effect and the length of this PBS is only 160 μm. Meanwhile, this PBS possesses the maximum ER of −72.1 dB and a 1020 nm-long operating bandwidth of extinction ratio greater than 20 dB, ranging from 2.92 to 3.94 μm. Additionally, with the existing manufacturing process, the device has a high feasibility. It deserves expecting that the proposed PBS has extensive application prospects in fields such as gas sensing, medical surgery, environment monitoring, optical imaging and the new generation optical communication network.