Optical binary switch and amplitude modulator micromirror arrays

Edward S. Kolesar Jr.; Peter B. Allen; Noah C. Boydston; Jeffrey T. Howard; Simon Y. Ko; Josh M. Wilken

doi:10.1117/12.361281

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2 September 1999 Optical binary switch and amplitude modulator micromirror arrays

Edward S. Kolesar Jr., Peter B. Allen, Noah C. Boydston, Jeffrey T. Howard, Simon Y. Ko, Josh M. Wilken

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Proceedings Volume 3878, Miniaturized Systems with Micro-Optics and MEMS; (1999) https://doi.org/10.1117/12.361281
Event: Symposium on Micromachining and Microfabrication, 1999, Santa Clara, CA, United States

Abstract

Five types of micromirror arrays were designed and fabricated using a three-level, polysilicon, surface micromachined, micro-electromechanical systems (MEMS) process. The electrostatically deflectable micromirror designs included arrays of simple cantilever beams, torsion beams, tethered (piston-style) beams, circular membranes, and oval membranes. The smallest micromirror element was the simple cantilever beam, measuring 50 micrometer square. The largest micromirror element was the oval membrane; it possessed an active optical surface that was 320 micrometer by 920 micrometer. Each of the remaining micromirror designs have gold-coated polysilicon optical surfaces with geometries between these two limits. Electrostatically induced vertical deflections on the order of 2.75 micrometer were achieved. The torsion beam micromirror design exhibits both in-plane and out-of-plane deflection. The other micromirror designs only manifest in-plane deflections. The modeling phase focused on the microdynamical behavior of the torsion beam micromirror. The IntelliCAD^R finite element analysis program was used to generate a plot of the micromirror's deflection (d) versus applied direct current voltage (V). The data was least-squares fitted to the well- established V varies direct as d^3/2 relationship. A resonant frequency analysis predicted an approximate switching speed of 6 microseconds. The reliability (number of operational cycles) of each micromirror design, when operated with a rectified 60 Hz alternating current (ac) signal, was measured to exceed more than 1 million flexure events. Experimental evidence supporting the potential for using micromirrors as binary optical switches and amplitude modulators is also addressed.

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Edward S. Kolesar Jr., Peter B. Allen, Noah C. Boydston, Jeffrey T. Howard, Simon Y. Ko, and Josh M. Wilken "Optical binary switch and amplitude modulator micromirror arrays", Proc. SPIE 3878, Miniaturized Systems with Micro-Optics and MEMS, (2 September 1999); https://doi.org/10.1117/12.361281

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