All-Optical Micromirrors From Nanotube MOMS With Wavelength Selectivity

The photomechanical properties of carbon nano-tubes (CNTs) enable the construction of CNT-based optical actuators. Employing a microelectromechanical systems-compatible nanotube-patterning process by plasma etching, CNT ensembles are integrated into microsystems to realize microoptomechanical systems (MOMS) (CNT-MOMS), where nanotubes behave as both the structural materials and the actuation mechanism. In this paper, following the CNT-MOMS principle, we report on all-optical micromirrors from the CNTs. Photomechanical actuation of single-wall CNTs from polymer-/nanotube-fllm bimorph structures is designed to actuate the micromirrors. A large mirror angular displacement of 19deg is obtained under laser illumination. Bidirectional rotation of the micromirrors is realized by the incorporation of two symmetrical serpentine bimorph actuators with the mirror surface. Furthermore, to add controllability to the micromirror rotations, absorptive-type optical filters are combined with the mirror structure in a "suspended" filter assembly. With green and red optical filters incorporated in the micromirrors, they show rotational selectivities of 10:1 and 20:1 for the 532-and 658-nm lasers, respectively. Depending on the wavelength of the incoming light, it could be selectively modulated into opposite directions by the micromirror.