High-performance terahertz polarization filter based on the anti-resonant fiber

A novel terahertz polarization filter based on the anti-resonant fiber is designed and analyzed. The polarization extinction ratio (PER) is improved by using high-resistivity silicon (HRS) as the bulk material in conjunction with a double conjoined tube cladding structure. The effects of the structure and material of the anti-resonant fiber on the polarization filtering characteristics are analyzed by the finite element method. The PER of the anti-resonant fiber reaches 100 dB and the insertion loss of y-polarization fundamental mode (YPFM) is less than 0.66 dB at 1 THz when the anti-resonant fiber length is 5.58 cm. The bandwidth can be expanded by changing the fiber length and for a fiber length of 8 cm, the frequency bandwidth is 0.92–1.14 THz and the insertion loss is less than 3 dB. The polarization filter is demonstrated to deliver excellent performance in the terahertz frequency range and has large commercial potential in terahertz communication and biomedical spectroscopy.