Integrated self-assembling and holding technique applied to a 3-D MEMS variable optical attenuator

The application of polysilicon/gold bimorph stress-induced curved beams for three-dimensional self-assembly of MEMS devices is reported. The mechanical principle behind this self-assembling procedure is presented and comparison with current assembling methods are made. With this self-assembling technique, no postprocessing is required. A free-space optical MEMS device in the form of a variable optical attenuator (VOA) has been fabricated and self-assembled using this technique. The angular elevation of the self-assembled structures and the attenuation characteristics of the optical MEMS device are reported. The VOA has a measured dynamic attenuation range of 44 dB at 1.55 μm optical wavelength. The bending of the bimorph beams is also temperature controllable, and the thermal behavior of the beams is also reported.