Jakeya Sultana

Porous core photonic crystal fibre for ultra-low material loss in THz regime

An extremely low-loss porous core circular photonic crystal fibre is presented for terahertz (THz) wave guidance. Much of attention is given to the geometries of the fibre to increase the fraction of power transmitted through core air holes. The finite-element method has been used to compute the modal characteristics of the fibre. Simulation results exhibit an ultra-low material loss of −0.05 cm−1 which is one-fourth of the bulk material loss and almost half of the useful power goes through core air holes at a frequency f = 1 THz. Besides, single-mode properties, confinement loss and dispersion of the fibre are rigorously discussed. The proposed fibre can be fabricated using capillary stacking or sol–gel technique and is useful for transmission applications in the THz frequency band.

Extremely low-loss, dispersion flattened porous-core photonic crystal fiber for terahertz regime

Abstract. A porous-core octagonal photonic crystal fiber (PC-OPCF) with ultralow effective material loss (EML), high core power fraction, and ultra flattened dispersion is proposed for terahertz (THz) wave propagation. At an operating frequency of 1 THz and core diameter of 345  μm, simulation results display an extremely low EML of 0.047  cm−1, 49.1% power transmission through core air holes, decreased confinement loss with the increase of frequency, and dispersion variation of 0.15  ps/THz/cm. In addition, the proposed PCF can successfully operate in single-mode condition. All the simulations are performed with finite-element modeling package, COMSOL v4.2. The design can be fabricated using a stacking and drilling method. Thus, the proposed fiber has the potential of being an effective transmission medium of broadband THz waves.

Near-zero dispersion flattened, low-loss porous-core waveguide design for terahertz signal transmission

Abstract. We demonstrate a photonic crystal fiber with near-zero flattened dispersion, ultralower effective material loss (EML), and negligible confinement loss for a broad spectrum range. The use of cyclic olefin copolymer Topas with improved core confinement significantly reduces the loss characteristics and the use of higher air filling fraction results in flat dispersion characteristics. The properties such as dispersion, EML, confinement loss, modal effective area, and single-mode operation of the fiber have been investigated using the full-vector finite element method with the perfectly matched layer absorbing boundary conditions. The practical implementation of the proposed fiber is achievable with existing fabrication techniques as only circular-shaped air holes have been used to design the waveguide. Thus, it is expected that the proposed terahertz waveguide can potentially be used for flexible and efficient transmission of terahertz waves.

A highly birefringent slotted-core THz fiber

We present a slotted porous-core microstructure polymer fiber for polarization maintaining (PM) guidance of terahertz (THz) waves. The numerical analysis is performed using a full vector finite element method (FEM). Our proposed structure contains a compact hexagonal lattice in the cladding and rectangular slotted air-holes inside the core. Geometries inside the core have been designed to introduce asymmetry which results in a high modal birefringence of ∼0.08. Moreover, majority of the mode power is propagated in air medium to exhibit a very low effective material loss of ∼0.08 cm−1. Some other modal characteristics of the fiber are also discussed rigorously, which include confinement loss, mode power fraction, dispersion properties etc.