A novel out-of-plane micro-mirror actuator

Abstract

A novel micro-bridge actuator that can satisfy the important requirements for optical switching has been designed, fabricated and tested. These important properties of the actuator include bi-stability, large out-of-plane movement, bi-directionality and electro-thermal actuation. The monolithic integration of a micro-mirror with this actuator is critical to demonstrate its application for optical switching in planar light circuits. In this paper, the design, simulation, fabrication and testing of the integrated system will be presented. The design and simulation issues include (i)the design of the micro-mirror that can be integrated and yet maintain the bi-stability behavior of the micro-bridge (ii) ANSYS simulations to substantiate the design (iii) the design of the dimensions of the mask lay-out of the micro-mirror to provide the desired micro-mirror size on the micro-bridge. The integrated system was fabricated on (110) oriented wafer. A vertical flat mirror, with verticality of 89.5° and a roughness of about 10nm has been obtained. The fabricated optical switch is laser diced, packaged, wire-bonded and tested. A free space optical path is established by micro-positioning optical fibers on the surface of the wafer in etched grooves to demonstrate optical switching. The optical system is actuated between the ON and OFF positions by driving 16mA and 10mA currents through the legs and bridge parts of the micro-bridge for respectively.