A novel THz wave Photonic Crystal Fiber（THz-PCF）is designed with a low-loss material polyethylene as the substrate.Its single mode cutoff frequency

dispersion and loss are numerically simulated using the full-vector finite element method.The results show that the frequency range of the THz single-mode propagation can be regulated by changing the cladding air hole period

air hole diameter and fiber core air hole diameter.When the cladding air hole period is 400μm

the claddingair hole diameter is 100μm and fiber core air hole diameter is 40μm

the broadband single-mode propagation range can not only be increased to 0.1

5

THz

but also the waveguide dispersion can be controlled at±0.5ps/（nm·km）within the frequency range of 0.5

5

THz.Moreover

the modal confinement loss will gradually decrease with the increase of the frequency and the minimum propagation loss will be 3.86dB/m at 2.8THz.