Low-Actuation-Voltage MEMS for 2-D Optical Switches

This paper discusses the design, fabrication, and test results of electromagnetically actuated two-dimensional (2-D) microelectromechanical systems (MEMS) optical switches. The switching element consists of a 20 mumtimes500 mumtimes1200 mum vertical micromirror, which is monolithically integrated with an actuation flap. The micromirror is made by anisotropic tetramethyl-ammonium-hydroxide wet etching with an optical insertion loss of about 0.2 dB. A maximum insertion loss of 2.1 dB has been experimentally demonstrated for a 10 times 10 2-D optical crossconnect switch. The actuation flap has double layers of spiral metal coils to generate a large actuation force with the permanent magnets placed at the bottom of the MEMS chip. The magnetic flux is created on the surface of a pair of opposite polarized magnets to precisely control the moving direction of the vertical mirror. The required voltage is less than 0.5 V, and the power consumption is about 3.5 mW for a switching element. Due to the center symmetric design and the stress-free characteristic of the micromirror, the temperature dependence loss is demonstrated to be as low as 0.05 dB. A switching time of 5 ms is achieved by applying the proper driving waveform