Design and characterization of highly birefringent chalcogenide As 2 Se 3 glass photonic crystal fiber with low confinement loss

Abstract

Abstract: A new simplified structure of highly birefringent chalcogenide As 2 Se 3 glass Photonic Crystal Fiber (PCF) with low confinement loss is designed and analyzed by using fully-vectorial finite element method. The effective indices, confinement losses, birefringence and chromatic dispersion of fundamental polarized mode are calculated in the proposed PCF. It is also shown that As 2 Se 3 glass PCF provides lower chromatic dispersion and less confinement loss compared to silica PCF of the same structure and hence such chalcogenide As 2 Se 3 glass PCF have high potential to be used in dispersion compensating and birefringe nce application in optical communication systems. Keywords : Photonic crystal fiber, Birefringence, Chalcogenide glass, Confinement Loss . 1. INTRODUCTION The Photonic crystal fibers (PCFs) have generated great amount of interest in optical communication over the past decade [1-3] as they exhibit many attractive optical properties such as endlessly single mode operation, controlled dispersion, large birefringence, supercontinuum generation and soliton propagation [4-8] over a wide range of wavelengths, that can not be realized in conventional fibers. The light guidance in PCF or holy fiber is based on one of the two mechanisms: effective index guid ance and Photonic Band Gap (PBG) guidance. In effective index mechanism, light is guided based on the total internal reflection between a solid core and cladding region with multiple air-holes [2]. On the other hand, photonic band gap mechanism, have the capabilities to control the guidance of light with a certain frequency band [9, 10] . One of the most fruitful aspects of PCFs is their applications as Polarization maintaining (PM) PCFs. Different approaches have been investigated to realize PM PCFs, which is generally based on birefringence. The key point in realizing the birefringence is to destroy the symmetry of fiber structure and increase the effective index difference between the two orthogonal polarization modes. The structural symmetry can be destroyed either by altering the air hole sizes near the core area [6], or by distorting the sh ape of the air holes (elliptical air holes) [11]. The most common technique to break the PCF structural symmetry is by changing the air hole sizes along two orthogonal axes near the core region. This results in increasing the difference between the effective indexes of the orthogonal polarization modes. To the best of our knowledge, highest birefringence in PCFs is report ed with elliptical air holes however, elliptical air holes are ve ry difficult to control during the fabrication process [11] PMFs have extensive application in optical communications (e.g. polarization-sensitive optical modulators) and fiber-optic sensing (e.g. fiber gyroscopes). PMFs are also required for high bit rate transmission systems as they can eliminate polarization mode dispersion (P MD) and also stabilize the functional performa nce of optical devices. Recently polarization maintaining (PM) PCFs have been fabricated and their transmission characteristics have been reported [12] using two different air hole diameters along two orthogonal axis near the core region. PM PCF can be of one order higher magnitude than that for conventional PMFs and is reported to be in the order of