MEMS-based planar optical switching solutions with integrated silicon nitride photonics for telecommunication applications

Abstract

High power consumption and long-and-complex assembly procedures have increased production costs related to optical systems used in data centers around the world. Such systems also rely upon optical-electrical-optical (OEO) conversion for switching optical signal in the telecommunication channel(s). Microfabrication technology can make complex optical systems which do not require the energy intensive OEO conversion a reality at low cost. Microelectromechanical systems (MEMS) have been integrated with silicon (Si) photonics components for low power optical switching solutions in the past. Such integration provides limited flexibility in the control over Si based optical components and Si based movable MEMS layer because both often use the same Si device layer in a conventional silicon-oninsulator (SOI) wafer. SOI-based MEMS integration with silicon nitride (SiN) photonics components enables independent control over optical component and MEMS designs. Lower scattering loss due to sidewall roughness, less sensitivity to width variations, and wide operating wavelength range make SiN a promising alternative to Si. Current optical switching solutions with SiN rely upon thermal tuning of optical components Mach-Zehnder interferometers (MZI) and micro-ring resonators. This kind of optical switching consumes high power and operates at high temperature. Also, the operating wavelength range is limited by the optical filter design. In this thesis, we propose a PhD project on the design, optimization, and integration of SOI-based MEMS actuators with SiN photonics for optical switching with wide operation wavelength range. The platform developed during this project integrates MEMS actuators with SiN channel waveguides to implement 1 x 3 and 1 x 5 optical switches with minimal optical transmission loss, low power consumption, and wide operational wavelength range. Minimizing the optical loss in a MEMS based SiN optical switch requires residual stress management and precise design engineering. Commercial multi-user fab process PiezoMUMPs was used to validate MEMS designs before integration with SiN waveguides. Various aspects leading to optical loss in a MEMS integrated SiN optical switch were investigated for performance improvement. The realized 1 x 5 optical switch has an operating wavelength range of 1540 nm to 1625 nm with a minimum average insertion loss of 2.2 dB and a maximum average insertion loss of 7.5 dB. The 1 x 5 optical switch operates at ≤ 90 V with the optical loss reduction mechanism working at 120 V.

Date	11 Jun 2024
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Nabki (Supervisor) & Michaël Ménard (Co-supervisor)