Abstract
Interests on low-loss terahertz (THz) waveguides are increasing due to their remarkable applications in various fields. Since most the materials are highly absorbent to THz waves therefore it is an ongoing challenge to obtain a low-loss waveguide. This paper presents a novel porous-core square lattice photonic crystal fiber (PCF) for efficient transmission of THz waves. The guiding properties of the proposed fiber are characterized by using finite element method (FEM) with circular perfectly matched layer (PML) boundary conditions. It is demonstrated that the designed PCF shows very low effective material loss (EML) of 0.076 cm-1 at 1.0 THz that indicates about 62 % reduction of bulk absorption loss of the background material. In addition to this, the proposed fiber exhibits low confinement loss of 8.96 × 10-3 dB/cm and low flattened dispersion of 0.96 ± 0.086 ps/THz/cm for the optimal design parameters. Other important propagation characteristics such as single mode propagation, power fraction, and bending loss are also investigated thoroughly. A porous-core PCF is an efficient mechanism for the transmission of THz waves. The proposed low-loss and low-dispersion PCF can find numerous applications in THz regime.
Highlights
Interests on low-loss terahertz (THz) waveguides are increasing due to their remarkable applications in various fields
In recent years, enormous efforts have been paid to THz photonic crystal fiber (PCF) due to their applications in multidisciplinary fields including remote sensing [1], imaging [2], security screening [3] and THz time domain spectroscopy [4]
The commercially available finite element method (FEM) based on state-of-the-art COMSOL v.5.0 has been used to design and characterize of the proposed porous-core square lattice PCF
Summary
The commercially available FEM based on state-of-the-art COMSOL v.5.0 has been used to design and characterize of the proposed porous-core square lattice PCF. The minimum element size has been fixed about 0.81 μm, which is enough for mapping different sizes of air holes. Throughout the simulation, finer element size has been used to obtain greater degree of accuracy. During the simulation the bulk material absorption loss of 0.20 cm-1 has been inserted, which is comparable with the experimental results reported in [19]. Dry air is the most transparent medium for THz waves having almost no absorption (αm = 0) in THz frequency bands [18, 30]. Absorption loss of air has not been taken into account during the calculation of different losses. It should be mentioned that losses of the proposed fiber have been studied for THz electromagnetic wave intensity
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