Comparison of three different microring resonator-based add-drop filters for Photonic Integrated Circuits’ telecom applications

Abstract

We report the design, simulation, and performance comparison of three variants of microring resonator (MRR)-assisted optical add-drop-filter (OADF) in terms of their (i) device loss characteristics, (ii) free spectral ranges, (FSRs), (iii) full-width at half maximum (FWHM), and (iv) design complexity. The three MRR-OADFs were (a) Racetrack-based OADF using a typical waveguide directional coupler (DC), (b) MZI-based OADF using Mach-Zehnder Interferometer (MZI) as DC, and (c) Tapered-MZI-based OADF using a tapered waveguide (to minimize optical transmission loss) together with MZI as DC. The waveguide material was silicon nitride (Si₃N₄) while the substrate was silicon dioxide (SiO₂). We used the Finite-Difference Time-Domain (FDTD) solver of Lumerical MODE to simulate their performances. We optimized their parameters by (i) varying the MZI's arm height, (ii) MZI's delta length, and (iii) the ring radius.