“Hexagonal Lattice Photonic Crystal Fiber with Low Confinement Loss and Low Chromatic Dispersion”

Abstract

In this paper, We design a novel Hexagonal Lattice photonic crystal fiber (PCF) made of soft glass achieving low confinement loss and low chromatic dispersion through the optimization of the arrangement and diameter of circular air holes. The motivation behind this is to optimize the design parameter of PCF to gain low-flattened chromatic dispersion and low confinement loss at wide wavelength range. This new design of PCF having low-flattened chromatic dispersion and low confinement loss in wide wavelength range is demonstrated by carefully adjusting the air holes in each rings, air holes dimensions and spacing between air holes or pitch. 2- D finite difference time domain (FDTD) method is used for the analysis of this PCF Keywords: Photonic crystal fibre (PCF), FDTD method, dispersion, confinement loss I. INTRODUCTION Optical Fibers have brought a great revolution in the field of Communication as they have provided better quality and good properties of the signal. But they also had limitations with respect to losses, dispersion and non linearity. Photonic-crystal fiber (PCF) is a new class of optical fiber based on the properties of photonic crystals. Because of its ability to confine light in hollow cores or with confinement characteristics not possible in conventional optical fiber. Photonic crystal fibers (PCFs) were first demonstrated in 1996 and have attracted much attention in recent years regarding new optical fiber applications (4). The most important property of PCF are that they can possess dispersion properties that are significantly different from those of conventional optical fibres, because their cladding portion consist of micrometer size air holes that run parallel along the length of the fibrer. PCFs provide confinement and guidance of light in a defect region around the centre as they are single- material fibers with an arrangement of air holes running along the length of the fiber. For the light confinement mechanism, index guiding PCFs rely on total internal reflection to confine light in the region of a missing air hole forming a central core. PCF is now finding applications in fiber-optic communications, fiber lasers, nonlinear devices, high-power transmission, highly sensitive gas sensors, and other areas. Photonic crystal fibers may be considered a subgroup of a more general class of microstructured optical fibers, where light is guided by structural modifications, and not only by refractive index differences. Several methods are used for the analysis of PCFs each having its own advantages and disadvantages. In this work, the FDTD method is used to find characteristics of PCFs. Confinement loss (CL), including cladding material losses, is comprehensively evaluated for TE and TM modes of photonic crystal fibers. However, confinement loss can significantly degrade the performance of devices based on such small core fibers. We also identify a range of fiber designs that result in high fiber nonlinearity and low confinement loss. In this paper we have tried to study confinement loss by proposing the four rings of circular shape of holes having the radius of 0.8um with lattice pitch of 2.3um and simultaneously we have also tried to study the dispersion characteristics and tried to confine it to nearly zero dispersion. PCFs can have a significantly larger numerical aperture than conventional fiber types because the cladding region can be mostly comprised of air. When this is combined with a wavelength-scale core, PCFs can provide tight mode confinement (i.e., small values of the effective mode