Enhanced Optomechanics with Nanostructured Material*

The maximum pressure on a planar surface is understood to be twice the incident wave power density normalized by the background velocity. We demonstrate for the first time that this pressure can be exceeded by a substantial factor by structuring a surface. Experimental results for direct optomechanical deflection of a nanostructured gold film on a silicon nitride membrane illuminated by a laser beam are shown to significantly exceed those for the planar surface. This enhanced pressure can be understood as being associated with an asymmetric optical cavity array realized in the membrane film, and a simple one-dimensional model explains the basic picture. Force control depends on the material properties and the geometrical parameters of the structured material. The interplay between material, structure at the nanometer-scale, and optical force should have substantial consequences in applications that include all-optical communication, remote actuation, propulsion, and biophysics.