In this paper, we present design, fabrication, and test results of a novel wavelength-selective MEMS switch for integrated optics. The device is based on switching of a ring resonator add-drop filter by use of an electrostatically-actuated MEMS bridge. We have demonstrated the wavelength-dependant switching capabilities of a prototype device; however, the residual stress in the bridge caused sagging of the bridge and high insertion loss to the optical output. Therefore, we are investigating the use of titanium nitride (TiN) for the MEMS bridge material. TiN has ideal characteristics both mechanically and electrically. It can also be annealed to lower the residual stress to almost zero. We have fabricated the MEMS bridge with TiN and done some preliminary experiments on the structure. The results show promise for the use of this material in our device, and more generally as a structural material. We have also designed closed-loop feedback control for precision positioning of the bridge. This enables this device to tune the selected wavelength over one full channel (30nm) for use as a tunable optical filter. The feedback scheme is based on using the bridge as one electrode of a capacitive sensor, and simulations indicate that the bridge position can be controlled to 2.5pm accuracy. Modifications of the device could also be used as a variable optical attenuator.

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