Content area
Full Text
Abstract- Designing a power splitter with five ports has been shown in this article. In order to prevent the direct coupling between waveguides, a T-shaped structure with an appropriate distance has been used. The coupling between the parallel photonic crystal waveguides is based on multimode interference, while selecting the output efficiency is performed by setting the refractive coefficients and radius of cavities in the coupling area. The photonic crystal of the splitter has a square-shaped structure made of silicon rods with lattice constant "a", radius of 0.2a and linear refractive index of n=3.4. The filling factor of this structure is r/a=0.18. Characteristic curve of the power splitter has been simulated by means of finite difference time domain (FDTD) method. The present device can be used in the future photonic integrated circuits and optical network applications.
Keywords- Photonic crystal, power splitter, coupling area, finite difference time domain (FDTD)
1. INTRODUCTION
Choosing an appropriate environment for light emission with minimum power dissipation is desirable in optical devices. Photonic crystals are the novel type of optical structures that create a suitable environment for light emission [1]. The photonic crystals have become a subject of great interest during the past few years as a result of exhibiting good features [1, 2]. Photonic crystal is an environment of alternate optical properties wherein at least two materials with different dielectric constant are repeated periodically. Some stopping bands in the structures make electromagnetic wave propagation impossible. By causing a defect in the photonic crystal structures, some virtual modes within band gaps are produced that can act as a cavity resonance or waveguide [3]. Through directional coupling between two or more photonic crystal waveguides, it is possible to create power splitters, optical switches [4], polarization splitters [5, 6], mirrors [7, 8], splitters [9] and also filters [10, 11]. Among the devices mentioned above, the splitter is one of the most important components in the optical integrated circuits being used in many systems. The devices made by the photonic crystal structures have some advantages such as considerable reduction in their size compared to their counterparts, whereas as a result of this unique feature, they lead to miniaturization and integration of the optical devices in large scale. Many devices used in optical integrated...