Impact of Core Diameter and Porosity on Confinement Loss in Photonic Crystal Fibers Across Terahertz Frequencies

This study investigates the impact of core diameter and porosity on confinement loss (CL) in photonic crystal fibers (PCFs) across terahertz (THz) frequencies ranging from 1 THz to 1.5 THz. Using a finite element method, we analyze the variation in confinement loss as core diameter and porosity are altered between 250 nm and 350 nm, and 30 % to 60 %, respectively. The results demonstrate a clear relationship between increasing core diameter and a reduction in confinement loss, with higher porosity contributing to greater loss at the same core diameters. Specifically, effective material loss (EML) reaches a maximum value of 0.07444 m⁻¹, while confinement loss (CL) is as low as 1.97×10⁻⁷ m⁻¹ at optimal core diameters and porosities. The study also explores how these structural parameters affect EML and the effective mode area (Aeff), revealing that both EML and Aeff increase with frequency. The influence of porosity on CL becomes more pronounced at higher frequencies, highlighting the trade-off between designing fibers for low loss and optimizing for effective mode area. This research provides key insights into optimizing PCF design for terahertz applications, where minimizing confinement loss is critical for efficient wave propagation.