Analysis of Photonic Crystal Fibers Using a Full-Vectorial Imaginary-Distance Finite-Element Beam Propagation Method
Date Issued
2007
Date
2007
Author(s)
Peng, Chan-Huan
DOI
en-US
Abstract
In this work, we adopt the full-vectorial finite element
imaginary-distance beam propagation method (FE-ID-BPM) based on the curvilinear hybrid edge/nodal elements and the incorporated perfectly matched layers (PMLs) to accurately analyze two types of photonic crystal fibers (PCFs) guiding light by different mechanisms, the modified total internal reflection (TIR) and the photonic bandgap (PBG) guiding.
We first analyze the modal characteristics as well as the coupling characteristics of a single-polarization single-mode PCF (SPSM-PCF) coupler through adjusting the diameters of the larger inner air holes and the smaller cladding air holes. From the simulation results, one can observe that the position and the width of the SPSM coupling region can be tailored through adjusting the hole diameters and the coupling length is more sensitive to the changing of the diameters of the smaller cladding air holes than those of the larger inner air holes. Next, we analyze an air-core photonic crystal bandgap fiber (PBGF) which more resembles the experimental structure due to the three types of polygons with their corners being smoothed by circles being used to approximate the air holes. We perform a complete searching
for the propagation modes in this air-core PBGF. From the analysis results, the existence of the surface modes and the occurrence of the avoided crossings are confirmed. In addition, the confinement losses and the GVDs of the fundamental air-core mode of the air-core PBGF are also scrutinized and they are observed to be strongly modified by the presence of the avoided crossings. To understand the influence of the surrounding air-hole rings on the propagating modes, a four-ring PBGF is studied and the same
numerical tests as in the six-ring PBGF are performed. We find that the real parts of the effective indices of the four-ring PBGF are very close to those of the six-ring PBGF while the confinement losses of the four-ring PBGF are much larger than those of the six-ring PBGF.
Subjects
光子晶體
光纖
有限元素
波束傳播法
虛軸波束傳播法
單極化單模態
耦合器
空氣纖心
能隙
波導
photonic crystal
fibers
finite element
beam propagation method
imaginary-distance beam propagation method
single-polarization single-mode
coupler
air-core
bandgap
waveguide
Type
thesis
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