Low Loss Flatband THz Guidance in Nodeless Antiresonant Hollow Core Fiber

A simpler hollow core antiresonant fiber structure is designed where the proper optimization of our structure leads toa very low effective material loss and the addition of bar contributes for the confinement loss reduction significantly. The results show that a low effective material loss of 0.0248 dB/m$\sim$0.032dB/m at 1.3-1.0 THz and very low confinement loss (order of $\sim10^{-4}$dB/m) lead to the lowest total transmission loss of 0.025 dB/m at 1.28 THz. The low loss transmission bandwidth of $\sim$0.88 THz (0.8 THz to 1.68 THz) with total loss of 0.06 dB/m and a wide flat-band (0.96 THz) near-zero dispersion is obtained over the frequencies of interest. Other related fiber parameters (single mode and bending loss performance) are also discussed. The presented fiber can be a potential candidate for future low loss and lowcost THz waveguides design.