Fabrication of an Electrostatic Actuated Dielectric Mirror With Free-Standing Layers of Polymer

Common materials used in dielectric mirrors are inorganic and rigid such that their optical properties cannot be modified. Here, we developed a method to fabricate a dielectric mirror with free-standing flexible layers that can be actuated by applying an electrostatic force or air pressure between the top and bottom ones. The membranes are sequentially compressed by reducing the structure reflectance by eliminating the air layers, where reflectance is the total electromagnetic power reflected divided in the incident one. A potential bias is applied between the layers of up to 30 V and an actuation time is shown to be less than 4.1 ms, recorded with a camera at 240 frames/s. Mirrors with length and width of up to
$230~\mu \text{m}$
each were achieved with three polymer/air layers. The polymer free-standing layers thickness ranged from 840 to 1240 nm and the air gaps from 140 to 400 nm. The small gaps and the large length of the mirrors allow fast actuation with relatively low voltages. The mirrors can be designed to reflect specific colors of the visual spectrum with potential application for color reflective displays.