3D free space thermally actuated micromirror device

A thermally actuated free space single crystal silicon micromirror device has been developed using one wafer low cost fabrication process. The device consists of a central mirror plate symmetrically joined with four thermal bimorph actuators through flexural springs. All the structural components of the device are fabricated in single crystal silicon using bulk silicon micromachining technology. Composite cantilevers of single crystal silicon, silicon dioxide, and aluminum are used as bimorph thermal actuators. This is an analogue micromirror device, which operates very accurately within an angular range for steering light beam in free space. The micromirror was demonstrated to achieve up to 10° repeatable angular deflection, 8-13 ms thermal response time, and 29 cm radius of curvature. The device was operated continuously for 100 million switching cycles at 40 Hz; no change in performance was observed which shows a good structural reliability. The target application area is optical communication networks; however, the device is equally useful for other scanning type of applications.