A newer and efficient solid core with air holes and ring based circular photonic crystal fiber (C-PCF) design is proposed, developed, and studied. The C-PCF structure with a ring core and three layers of air holes is developed to communicate terahertz frequency of the range of 1 THz to 3 THz. Finite element method (FEM) is used to optimize the position, shape and dimensions of air holes and refractive index (RI) of material for the proposed PCF design and check the efficiency to support different orbital angular momentum (OAM) modes for communication. Our novel designed C-PCF supports multiple stable modes with mode purity above 0.9. Confinement loss is in the range of 10-12 dB/cm, highest effective mode area in the order of 1 mm2 is achieved in the investigated study for 3 THz transmission. The study observes that the performance of PCF is strongly dependent on RI of core and cladding.