Faculté des sciences

Tunable optical microsystems featuring vertical electrostatic comb drives

Overstolz, Thomas ; De Rooij, Rob (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2007 ; 1940.

This PhD thesis presents the realization of micro electro-mechanical systems for optical applications requiring very precise actuation. One of the requirements was the implementation of a vertical actuation mechanism based on comb actuators that allow accurate static displacements. Two devices have been realized following two different concepts for vertical comb drive actuators. One device... Plus

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    Summary
    This PhD thesis presents the realization of micro electro-mechanical systems for optical applications requiring very precise actuation. One of the requirements was the implementation of a vertical actuation mechanism based on comb actuators that allow accurate static displacements. Two devices have been realized following two different concepts for vertical comb drive actuators. One device provides a tilting platform of 2×2mm2 which can be used to tune an optical element assembled on top of the platform. Two sets of vertically staggered comb actuators are used to create a vertical force which pulls down the platform to one or to the other side. We achieved a tilt angle of ±3.5° at 80V in static operation. For demonstration purpose, we assembled a telecom resonant grating filter (RGF) onto the platform. We successfully scanned the entire telecom C-band (1530-1570 nm) by tilting the platform from -3.5° to +3.5°. The other device provides a triangular mirror of 1.7mm edge length which is suspended by three C-shaped beams. Three sets of asymmetric vertical comb actuators are used for actuation. The mirror can perform either a pure vertical (piston) displacement of up to 18 µm at 80 V, or a tip-tilt of up to 2.2 mrad at 50 V. The tip-tilt feature allows to correct a small wedge error with an optical component assembled on top of the device. Typical applications of such a device are tunable cavity systems where the required flatness of the mirror is of particular importance.