New THz Notch Filter Based on Cylindrical Periodic Structure

We propose and numerically analyze a new type of notch filter operating at terahertz frequencies, using a cylindrical periodic structure.This study takes place in the context of increasing demand for precise filtering devices in the terahertz frequency range, crucial for various applications in telecommunications, sensing, and medical field.This research focuses on the numerical analysis of the proposed structure, using the transfer matrix method to examine how changes in geometric parameters influence wave transmission.Particular attention is given to the effects introduced by the radii of the cylinders making up the structure.The principal results show that perfect symmetry (radii R1 = R2) produces no significant transmission dip, indicating the absence of resonance in the frequency band studied.This configuration allows the device to function as a passive filter.The introduction of asymmetry (R1 ̸ = R2) leads to the appearance of transmission dips, meaning that the device functions as a notch filter, capable of blocking specific frequencies.This phenomenon offers a method of selective filtering, by "activating" or "deactivating" the filter's behavior.Our research demonstrates the potential of the proposed cylindrical periodic structure as an innovative solution for the design of notch filters in the THz range.The ability to precisely control wave transmission through geometrical adjustments opens up new ways to develop highly selective filter devices adaptable to various technological applications.