Transforming optical forces using thin-film metamaterials

Recently, a lot of interest has been paid to the possibility to dynamically actuate nanoscale devices using optical forces. These forces arise when linear momentum is transferred between electromagnetic fields and matter. In the past decade, optical forces have been used in the field of optomechanics, but they still remain too small for dynamic manipulation in photonic actuation systems. We show how transformation optics can enhance optical forces in such systems by altering the perceived separation distance, resulting in a more than tenfold enhancement of the optical force. This transformation can be implemented using single-negative metamaterial thin films. Additionally, we show how this lensing mechanism is robust to the dissipative loss associated with resonant metamaterials. Therefore, our results provide an alternative way to boost optical gradient forces in nanophotonic actuation systems and may be combined with existing resonator-based enhancement methods to produce optical forces with unprecedented amplitude.