Abstract:The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachining techniques. Off-state deflections of the cantilevers have been optimized to appropriately position them near the evanescent field of the resonator. Using electrostatic actuation, moving the cantilevers into this evanescent field, the propagation properties of the ring waveguide are modulated. We demonstrate 122 pm tuning of the resonance wavelength of the optical ring resonator (in the optical C-band) without change of the optical quality factor, on application of 9 V to a 40 µm long cantilever. This compact integrated device can be used for tuning/switching a specific wavelength, with very little energy for operation and negligible cross talk with surrounding devices. ©2011 Optical Society of America

A systematic study is presented on the modelling, fabrication and measurements of curled micro-bimorph cantilevers, which are composed of a dielectric beam with a metal electrode layer coated on top. The device, having stress-induced upward curvature in the electrical off-state, functions as a vertical electrostatic actuator for nanometre displacements. A detailed analysis is carried out of the resonance frequency of the cantilever as a function of its length, deflection and thickness of the upper electrode layer, including the effect of undercut. A Galerkin-based static model is used to predict the pull-in voltages which are validated by measurements. A dynamic model is used to investigate the shift in resonance frequency by the electrostatic spring softening effect, which is evaluated against experimental data. The measured shift in resonance frequency is further extrapolated to non-destructively predict the pull-in voltages.

A photonic crystal slab waveguide (PhC-WG) with an integrated MEMS bimorph cantilever actuator has been successfully fabricated using deep UV lithography and surface micromaching techniques. The cantilever is equipped with tips that are self-aligned with respect to the holes of the PhC-WG such that on electrostatic actuation, with modest voltages of less than 10 V, these tips move into the holes. This provides electro-opto-mechanical modulation of light-transmission, up to 80%, for interaction lengths as short as 10 µm. The device is monolithically integrated and designed to operate in the C-band of the telecommunication wavelengths.

We demonstrate a monolithically integrated micromechano-optical device where the resonance wavelength of a silicon ring resonator is tuned by perturbing the evanescent field with an electrostatically actuated silicon nitride microcantilever. The resonance wavelength can be tuned over 125 pm.

A technology to monolithically integrate micro-bimorph cantilevers equipped with tips that are self-aligned with respect to the holes of a 2D photonic crystal cavity-based channel-drop filter is presented. On electrostatic actuation, the tips move into the holes and provide electromechano-optical modulation of light. The technology allows the fabrication of tips on specific photonic crystal holes by controlling the hole diameter and the sacrificial layer thickness. The integrated device is both mechanically and optically characterized. A 180 pm wavelength shift at the first band edge of the photonic crystal cavity-based channel-drop filter is measured on the application of a 2 V dc voltage to the cantilever. This CMOS-compatible device is designed to operate in the C-band of the telecommunication wavelengths and constitutes a promising candidate for future integrated all-optical devices.