Sector-type high birefringence hollow-core anti-resonant terahertz photonic crystal fiber with low loss

A novel high birefringence hollow-core anti-resonant terahertz photonic crystal fiber based on cycloolefin copolymer (COC) is proposed. The cladding of the fiber is composed of four sector-type tubes with node-less structure. The properties of birefringence, confinement loss, effective material absorption loss, and power fraction are analyzed by using the finite difference time domain (FDTD) method. The numerical simulation results show that a high birefringence window (B >8×10−4) in the frequency range of 0.7–1.18 THz is obtained when the tube thickness is 0.09 mm. At 0.83 THz, the lowest transmission loss of 0.172 dB/m is attained, and the corresponding birefringence is 1.06×10−3. In addition, the bending loss and dispersion characteristics of the proposed fiber are investigated. It is found that a flatten and low dispersion in the frequency range of 0.7–1.47 THz, and an excellent bending performance in the y-direction with critical bending radius of 22 cm are obtained simultaneously.