Study of Waveguide Mode and Dispersion Property in THz Photonic Crystal Fiber

The characteristic equation of THz photonic crystal fibers is obtained with effective refractive index method. The mode distribution and dispersion are discussed. It's found that when air hole pitch is fixed, the cladding effective refractive index of photonic crystal fiber (PCFs), the cut-off frequency of higher modes, and the frequency of maximum and zero dispersion will become larger, the maximum dispersion will become smaller if the air hole radius decreases; when air-filling fraction is fixed, the cladding effective refractive index, the cut-off frequency of higher modes, and the maximum dispersion will become larger, the frequency of maximum and zero dispersion will become smaller if air hole radius increases. The transmission with single-mode zero dispersion in THz region can be realized according to the changes of air hole pitch and the air hole radius.