Widely Tunable MEMS-Based Fabry-Perot Filter

• Published in: Journal of microelectromechanical systems Vol. 18; no. 4; pp. 905 - 913
• Main Authors: Milne, J.S., Dell, J.M., Keating, A.J., Faraone, L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.08.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuator materials; Actuators; Applied sciences; Broadband; Capacitive sensors; Curvature; Curvature correction; doubly supported beam; Electronics; Exact sciences and technology; Fabry-Perot; fixed-fixed beam; infrared; Infrared detectors; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; material properties; Mathematical analysis; Mechanical instruments, equipment and techniques; Mechanical variables measurement; microbridge; microelectromechanical systems (MEMS); Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Mirrors; MOEMS; optical filter; Optical filters; Physics; Plasma measurements; pull-in; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; short-wave infrared (SWIR); snap-down; stress; Stress measurement; Stresses; Studies; travel range; Tuning; tuning range; Wavelength measurement; Young's modulus; Integrated optics; Actuators; tuning range; doubly supported beam; snap-down; Electromechanical filters; infrared; Fabry-Perot; travel range; optical filter; microbridge; Young's modulus; Wide band; Strain gradient; Modelling; Mirrors; Microelectromechanical device; Fabry-Perot interferometers; Infrared detectors; stress; Elastic constants; microelectromechanical systems (MEMS); Deformation modulus; Capacitive transducer; pull-in; short-wave infrared (SWIR); Low power; MOEMS; Curvature correction; Young modulus; Wavelengths; material properties; fixed-fixed beam; Nanotechnology
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2009.2024793

This paper describes the use of strain stiffening in fixed-fixed beam actuators to extend the tuning range of microelectromechanical-systems-based Fabry-Perot filters. The measured wavelength tuning range of 1.615-2.425 mum is the largest reported for such a filter. Curvature in the movable mirror was corrected using a low-power oxygen plasma to controllably alter the stress gradient in the mirror. After curvature correction, the linewidth of a filter was 52 nm, close to the theoretical minimum for our mirror design. As a proof of concept, a filter was bonded to a broadband infrared detector, realizing a wavelength-tunable infrared detector. All measured data have been compared to theoretical models of the optics and mechanics of the filters, with excellent agreement between theory and measurement demonstrated in all cases. Finally, the Young's modulus and stress of the actuator materials were extracted directly from the measured voltage-displacement curves, demonstrating a novel technique for material property measurement.