Cantilever design for tunable WDM filters based on silicon microring resonators

Abstract

Wavelength-division multiplexing (WDM) systems are essential building blocks in modern photonic integrated circuits (PICs), and could enable high-bandwidth connectivity in novel 3D integrated chip stack architectures. These systems can be realized with optical add-drop multiplexers (OADMs) implemented using optical microring resonators. A key feature of such optical filters is the possibility of controlling their frequency response, and extensive research has been dedicated to this end. This chapter focuses on the design and numerical validation of a frequency tuning mechanism based on a microelectromechanical system (MEMS) implementation, through a cantilever that is probing the evanescent field of the optical mode of a microring resonator. The chapter starts with a brief introduction on PICs and microring-based OADMs, along with considerations on the main parameters that can be controlled, and a summary of the state-of-the-art frequency tuning techniques. A detailed opto-mechanical analysis is then performed for the cantilever design, complemented with both mechanical and optical numerical computations.