Comparative Analysis of Compact Microring Resonator Architectures for Tunable Optical True Time Delay

Abstract

In this paper, we have carried out detailed analytical study of a compact continuously tunable optical time delay based on optimal ring resonator architectures that can reduce footprint and increase time delay at the same time. We have derived the complete mathematical equations such as time delay and design equations that characterize the devices. The performances of the new architectures are compared with the conventional racetrack ring resonator architecture on the same footprint area. We have used Silicon-on-insulator (SOI) technology platform for design and analysis. The peak time delay achieved in the new architectures is higher by 110% as compared with the conventional ring structure. The optimal device architectures' performances of side-coupled integrated spaced sequence of resonator (SCISSOR) structures for zero group delay dispersion (GDD) and wideband operation are analyzed. The delay per unit footprint area (dB/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and loss per unit delay (dB/ns) are computed for all architectures. The new optimal architecture and conventional one provides 43.0 ns/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 21.0 ns/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> respectively. This result signifies the compactness of the new optimal architecture. Thus, the proposed device is highly applicable in designing low complexity true time delay lines (TTDs) for phased array beamforming of RF /microwave signals.