Reconfigurable High-Resolution Microwave Photonic Filter Based on Dual-Ring-Assisted MZIs on the Si₃N₄ Platform

Abstract

We report a reconfigurable optical filter chip based on the Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> waveguide platform. Microwave filtering is realized using a device with optical-to-electrical mapping. The filter chip is based on a lattice structure with the dual-ring-coupled Mach-Zehnder interferometers (DR-MZIs) as the basic elements. Both the lattice and ring couplers are tunable, making the chip reconfigurable to various filter functions. A theoretical model is developed to analyze its optical filtering performance. Measurement reveals that the filter passband can reach hundreds of megahertz in the lower limit and several gigahertz in the upper limit. Various orders of infinite impulse response filters are implemented with a tailorable passband. The flexibility in tuning filter center frequency and passband makes it suitable in high-resolution adaptable microwave signal front-end processing.