Design & analysis of Optical Ring Resonator with Circular Cavity as Add-drop Multiplexer

From the last decade, there has been immense interest in development of optical components. Optical components can be broadly classified into two types viz. active and passive components. These components are used for purpose of splitting, multiplexing, filtering etc. In order to investigate performance of these components, computationally complex Maxwell’s equations are solved either in time or frequency domain. Numerous mathematical methods are developed to solve these equations for analysis of wave propagation inside optical components. The effectiveness of these method depends on the dimensions of the component, wavelength and step size used in the problem. Optical ring resonators are passive components, which are used as channel dropping filters in dense wavelength division multiplexing(DWDM). Filtering performance of ring resonators depends upon various parameters such as size and shape of cavity, coupling length, separation gap from adjacent waveguides etc. In this paper, finite difference beam propagation method(FDBPM) is used to analyze the filtering performance of optical ring resonator with circular cavity. The filtering performance is determined by selecting circular cavities with different diameters and its separation distance for adjacent parallel waveguide. Simulation results shows that maximum optical power can be dropped for circular cavity with smaller diameters with lesser separation gaps, which are consistent with theoretical results. This paper also investigates effect of negative separation gap on filtering performance of ring resonator.