In this present work, a novel structure of octagonal cladding with two elliptical air holes based on photonic crystal fiber (O-PCF) has been presented for the application of different types of communication areas within the terahertz (THz) wave propagation. There are five layers of octagonal design shape of circular air holes (CAH) in cladding region with elliptical design shape of two air holes in core area has been reported in this research work. This O-PCF fiber has been investigated by the perfectly matched layers (PML) with the finite element method (FEM). After the simulation process, our proposed O-PCF fiber shows a low effective material loss (EML) of 0.0162 cm −1 , the larger effective area of 5.88×10-8 m2, the core power fraction (PF) of 80%, the scattering loss of 1.22×10 -10 dB/km, and the confinement loss of 3.33×10 -14 dB/m at the controlling region of 1 terahertz (THz). Due to its excellent characteristics, this proposed O-PCF fiber gives proficient transmission of broadband terahertz waves of signals. Moreover, for different kinds of optical communication applications and biomedical signals, our suggested O-PCF fiber will be highly perfect in the terahertz (THz) regions.