A transformation-optical approach to enhance optical gradient forces with metamaterials

In the interaction between light and matter, linear momentum can be transferred from electromagnetic waves to particles to generate so-called optical forces. Recently, it has been suggested that optical gradient forces can be used to actuate nanophotonic devices since measurable displacements can be achieved [1]. The typical setup consists of two waveguides positioned in each other´s vicinity such that they are coupled through the interaction of the evanescent tails [2]. Although the gradient forces between these waveguides can be enhanced considerably with the use of electromagnetic resonators, the resulting displacements remain relatively small [1,2].