Microeletromechanical Systems for Tunable Ring Resonators on a Silicon Platform

Sammanfattning: Advancements in photonic integrated circuits, so-called PICs, have progressed fast in the last decades. More complex PICs are getting developed, which are promising in possibly offering advantages like low power consumption and high-performance computing. Re-programmable photonic FPGAs are one of these candidates. To make these PICs viable, fundamental building blocks based on photonics need to be developed. Some of those fundamental building blocks are tunable silicon ring resonators, which can be used to filter signals in the transmission of light through photonic circuits. Fabrication of PICs is developing and those components are getting smaller, which leads to a strong sensitivity of their behavior to nanometer-scale variations. That has created a need for active tuning of those devices to recuperate those variances. One promising way to tune silicon ring resonator devices is to integrate microelectromechanical systems (MEMS) into the tuning section of the devices, because of their local and low power actuation. They are prospective to eliminate drawbacks from usual actuation methods like thermal actuation, which comes with high power consumption and cross talk while heating the functional sections of the ring. In this thesis, we have measured and analyzed MEMS-tunable silicon ring resonators, featuring two different designs, being an all-pass ring resonator and an add-drop ring resonator. The MEMS in the design are used to change the gap between the waveguides in their directional coupler and phase shifter section to control the position and extinction ratios of the ring resonance dips, which has been successfully demonstrated for the all-pass ring resonator. For the add-drop ring resonators, we have obtained performance parameters of their resonances with an average Q-factor of 3000 over the measured wavelength ranged from 1460nm to 1580nm and the characteristic behavior of their transmission has been shown without actuation. Further investigation with MEMS actuation of add-drop ring resonators and passive measurements on all-pass ring resonators can be done for a better understanding of their behavior and functionality. This can be achieved by characterizing all-pass ring resonators in terms of obtained performance parameters and by active measurements on add-drop ring resonators, as we expect that their MEMS could enable similar functionalities as all-pass ring resonators. Our first characterization results confirm the potential of MEMS for ring resonator tuning and could enable future circuits based on ring resonators with low power consumption.