Design, Simulation, and Characterization of a Partial Negative Curvature Antiresonant Hollow-Core Fiber for Low Loss Terahertz Wave Transmission

The present paper demonstrates a novel partial negative curvature hollow-core fiber for low-loss terahertz transmission. In the optimized fiber structure, the tubes in the vertical direction are replaced by plate-like dielectric sheets, thereby achieving low loss and low blocked risk of 3D printing, while retaining a small fiber hollow core and fiber diameter. The 3D printed fiber is characterized by a terahertz time-domain spectroscopy (THz-TDS) system. The obtained transmission spectrum demonstrates the mode beating phenomenon and its peak position varies periodically with fiber length at short distances. The thin antiresonant walls endow the fiber with two broad low-loss windows of 0.2–0.4 THz and 0.55–0.85 THz. Besides, the x-polarization and y-polarization waves achieve minimum losses of 16.2 dB/m@0.28 THz and 16.0 dB/m@0.29 THz, respectively. Furthermore, our fiber has low experimental dispersions, namely −0.18±1.1 ps/THz/cm (x-pol) and 0.67±0.77 ps/THz/cm (y-pol). The experimental losses and dispersions match well with the simulation results. Additionally, the simulation results reveal that the fiber has the potential to attain a high birefringence of 10 ⁻³ .