Narrow Results

This paper proposes a novel model to attain high birefringence and low loss in a slotted core-based photonic crystal fiber (PCF) structure in THz regime. The performance of the proposed PCF has been evaluated by applying finite element method (FEM) with full simulation software COMSOL Multiphysics V-5.1. The proposed model gains good optical properties such as high birefringence of 0.24, low effective material loss (EML) of 0.03 cm${}^{-1}$, low confinement loss of 6.5 × 10${}^{-13}$ (dB/m), low scattering loss of 2 × 10${}^{-3}$ (dB/m) and low bending loss of 7.4 × 10${}^{-20}$ (dB/cm). The proposed structure also exhibits the flattened dispersion for wider frequency response. However, the real-life fabrication of the suggested model is highly feasible using the current technology due to the unique shape of circular air holes in the cladding region. The outcomes make the proposed PCF a stronger candidate for polarization-preserving applications such as sensing, communications and filtering operations in THz band.

A triangle-platform-index core fiber is proposed, in which the refractive index distribution in the cross-section of the fiber core is composed of several closely connected triangles and a platform at the outermost layer. The simulation results show that the proposed fiber possesses an extremely large mode field area of $3110\mu {\mathrm{\text{m}}}^2$ at the wavelength of $1.06\mu \mathrm{\text{m}}$, and achieves single-mode operation state near a bend radius of 17 cm. Furthermore, several different mode field distributions, including Gauss-like distribution, flatten distribution and hollow distribution, are achieved. The proposed fiber can benefit suppressing nonlinear phenomenon to increase the output power level of fiber laser, and promoting special industrial processing.

Generally, fiber with a large mode area is desired for fiber laser and beam delivery applications. But the use of these fiber types is restricted to linear optical applications due to the lower value of the nonlinear coefficient. This paper investigates a single material-based photonic crystal fiber (PCF) with improved optical characteristics, applicable for linear and nonlinear optics. The light propagation in the structure is explored by applying finite element solver-based COMSOL multiphysics software. Five nonlinear optical materials are utilized as background material to get the optimized material with high performance PCF. Using this PCF, the improved optical properties of PCF such as moderate effective mode area of 115.85 $\mu {\mathrm{\text{m}}}^2$, chromatic dispersion, confinement loss of 10${}^{-6}$ dB/m, the nonlinear coefficient of 543W${}^{-1}$Km${}^{-1}$, splicing loss of 2.013 dB, and numerical aperture are numerically analyzed. This single-mode PCF also shows the low bending loss for the bending radius of 7mm. The amended PCF structure is found to be suitable for high-power fiber laser, supercontinuum generation, wavelength conversion, and slow-light generation.