Sliding-blade MEMS iris and variable optical attenuator

• Published in: Journal of micromechanics and microengineering 2004-12, Vol.14 (12), p.1700-1710
• Main Authors: Syms, R R A, Zou, H, Stagg, J, Veladi, H
• Format: Article
• Language: English
• Subjects: Applied sciences; Circuit properties; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated optics. Optical fibers and wave guides; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Optical and optoelectronic circuits; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/14/12/015

An iris-type variable aperture fabricated using microelectromechanical systems (MEMS) technology is described. The device contains a number of shutter blades, which are each driven by a separate microactuator, and translated synchronously to create a variable polygonal aperture. The optical performance of devices with different numbers of blades is compared using simple analytic models and diffraction theory. The mechanism is simulated by finite element analysis. Four-blade devices driven by buckling mode electrothermal actuators are formed by double-sided patterning and deep reactive ion etching of bonded silicon-on-insulator and characterized experimentally. Symmetric deflections are obtained, and used to create a square pupil. Variable attenuation is demonstrated using optical fibres with thermally expanded cores.