2D MEMS electrostatic cantilever waveguide scanner for potential image display application

¹ Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
² Department of Electrical Engineering, University of Washington, Seattle, Washington, USA
³ Medical Device Innovation Center at National Cheng-Kung University, Tainan, Taiwan, R.O.C.
⁴ Department of BioMedical Engineering, National Cheng Kung University, Tainan, Taiwan, R.O.C.

^a Corresponding author: abong@uw.edu

Abstract

This paper presents the current status of our micro-fabricated SU-8 2D electrostatic cantilever waveguide scanner. The current design utilizes a monolithically integrated electrostatic push-pull actuator. A 4.0 μm SU-8 rib waveguide design allows a relatively large core cross section (4μm in height and 20 μm in width) to couple with existing optical fiber and a broad band single mode operation (λ= 0.7μm to 1.3μm) with minimal transmission loss (85% to 87% output transmission efficiency with Gaussian beam profile input). A 2D scanning motion has been successfully demonstrated with two fundamental resonances found at 202 and 536 Hz in vertical and horizontal directions. A 130 μm and 19 μm, corresponding displacement and 0.062 and 0.009 rad field of view were observed at a +150V input. Beam divergence from the waveguide was corrected by a focusing GRIN lens and a 5μm beam diameter is observed at the focal plane. The transmission efficiency is low (~10%) and cantilever is slightly under tensile residual stress due to inherent imperfection in the process and tooling in fabrication. However, 2D light scanning pattern was successfully demonstrated using 1-D push-pull actuation.