The inherent ability of silicon micromachining to provide a multitude of precision aligned optical components on a single die naturally facilitates optical communication trends towards installing larger cross-connects and transmitting many channels on individual fibers. A micromachined mirror array has been designed and fabricated using the Analog Devices, Inc. (ADI) Optical iMEMS (R) process. The single-chip mirror die consists of 84 mirrors arranged in a linear array with an average pitch of 95 μm. Each mirror is equipped with a pair of polysilicon actuation electrodes located beneath the mirror. These two electrodes allow each mirror to be independently rotated around the axis parallel to the long dimension of the array using off-chip voltage commands. An operating mirror tilt of +/- 2 degrees is achieved with less than 130 volts of actuation. The design objectives including high mirror fill factor, optimal air damping, low mirror-to-mirror cross talk, acceptable voltage levels, and robustness posed significant challenges. This paper will describe how these challenges were overcome using an interdigitated mirror layout. The mirrors were successfully fabricated with good yield and characterized through both customer and ADI testing.
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