Low Voltage Mems Analog Micromirror Arrays with Hidden Vertical Comb-drive Actuators

We report on a novel, polysilicon surface-micromachined one-dimensional (1-D) analog micromirror array. Large continuous DC scan angle (23.6° optical) and low operating voltage (6V) have been achieved using vertical comb-drive actuators. The actuators and torsion springs are placed underneath the mirror (137 × 120 μm) to achieve high fill-factor (91%). The measured resonant frequency of the mirror ranges from 3.4 kHz to 8.1 kHz. The static scanning characteristics show good uniformity (<±3.2%) for a 1 × 10 array with a mirror pitch of 150 μm. The measured DC scanning characteristics and resonant frequencies agree well with theoretical values. This micromirror array has applications in optical wavelength-division multiplexed (WDM) routers and wavelength-selective crossconnect (WSXC).