Low loss Slotted core photonic crystal fiber for terahertz radiation

Abstract

Fiber optic systems are important telecommunication infrastructure for world-wide broadband networks. Wide bandwidth signal transmission with low delay is a key requirement in present day applications. Optical fibers provide enormous and unsurpassed transmission bandwidth with negligible latency, and are now the transmission medium of choice for long distance and high data rate transmission in telecommunication networks. Terahertz radiation occupies a middle ground between microwaves and infrared light waves known as the terahertz gap, where technology for its generation and manipulation is in its infancy. The frequency band of 0.1-10 THz, known as THz band has brought potential applications in many important fields. For wave propagation, THz systems use free space as medium. But in free space, waves face many difficulties which is very big issue for wave propagation. So we have to use guided transmission instead of unguided transmission. Our main objective is to design an optical waveguide which will be able to transmit terahertz signal into longer distances. Low material loss and high core power fraction is major concern for designing a Terahertz photonic crystal fiber. Material loss occurs due to the use of bulk material in the background of photonic crystal fiber. Several ultra-low loss terahertz (THz) photonic crystal fibers (PCF) design have been proposed and inquired precisely. We proposed four photonic crystal fiber designs where two is slotted air hole inside the octagonal core, another one is slotted air hole inside the hexagonal core and finally last one is a circular air hole inside hexagonal core. All the simulations are performed with Finite Element Modeling (FEM) package, COMSOL 5.3b. The design can be fabricated using stack and drilling method. The investigation results have proved that the designed PCFs shows very low effective material loss (EML) such as 0.010 cm−1, 0.012 cm−1, 0.025 cm−1 and 0.029 cm−1, at 2.1THz, 1.6 THz, 1.6 THz and 1.7 THz respectively. The core power fractions of those proposed design are 70%, 60%, 50% and 49% respectively. Moreover, other optical parameter of those PCF such as effective mode area (EMA), confinement loss (CL), and dispersion have been investigated also. The proposed PCFs suggested flatted dispersion from 0.70 THz to 2.10 THz, 0.60 THz to 1.60 THz, 0.60 THz to 1.60 THz and 0.50 THz to 1.70 THz. The outcomes indicate that the proposed PCFs will be good candidates for THz or T-ray transmission as well as in the area of photonic devices also.