Photonic crystal based rat race coupler for optical applications

In this paper photonic crystal based rat race couplers having circular and/or elliptical rods are proposed which exploit the photonic band gap effect. 2D simulations of the proposed structures are also carried out using FDTD method. The effects of change of the shapes of rods, refractive index of wafer and wavelength of operation are also studied. It is observed that the performance of rat race coupler with all elliptical rods is similar to the conventional rat race coupler operating at microwave frequency. By changing the orientation of the elliptical rods in one of the proposed structures, inverse behaviour of that of conventional rat race coupler is observed. These structures can therefore find applications in power combiners/dividers at optical frequencies. (C) 2012 Elsevier GmbH. All rights reserved.