MODELING OF RING RESONATOR AS AN OPTICAL FILTER USING MEEP SOFTWARE

Abstract

Ring resonators are key components in modern optical networks. Their small size allows high density integration in optical photonic circuits due to the use of high index contrast. Ring resonator filters based Optical Filters for wavelength division multiplexing (WDM) are considered as one example in this technology. This thesis is a simulation study of Ring resonators which are widely used for various applications such as Optical antennas, Optical bandpass filters, Optical couplers and Optical oscillators. The description, design, simulation and layout of a ring resonator were carried out using Mit Electromagnetic Equation Propagation (MEEP) software. Coupling a closed loop resonator with a straight waveguide using evanescent coupling leads to a filter behavior of a new structure. By using the MEEP software, the transfer functions provide detailed physical interpretations of the resonator which are required to design good filter characteristics. Some of the characteristics include the Free Spectral Range (FSR), Finesse (F) and Quality factor (Q). The ring resonator modeled achieved a resonant frequency of 1.45518 x 1015 rad/s and resonance wavelength of 1.2955 μm, a single mode of 0.15076 GHz frequency was also achieved that resulted in a single mode source which is analytically solvable. Change in dielectric constant of the ring and perfect matched layers reduced greatly the power transmitted in the waveguide; hence leading to the downward shifting of the power. In addition an increase in length between the ring and the waveguide led to a decrease in the power coupled in the ring. A horizontal decrease in power was eminent when the computation cell and number of rings were increased from a single ring to triple rings. Vertical decrease in power and horizontal shifting of power coupled in the ring resonator were also achieved; which are the characteristics of fixed and tunable filters respectively. These research findings will help greatly in improving data and signal selection in communication as the process increase the speed of communication.