The coupling of electromagnetic (EM) radiation to mechanical motion is not only of fundamental interest but is also relevant to practical applications. In this thesis, I will describe experiments investigating the local EM stress on a metamaterial unit. While it is well-known that the EM field is strongly concentrated at resonance and the total EM force can be strongly enhanced from the ordinary radiation force, here we show that the enhancement in the local EM stress is even larger. A general recipe for isolating the EM contribution from photothermal effects will also be described. In another effort, we investigate the strong geometrical dependence of the Casimir force that arises from quantum fluctuations of the EM field. A monolithic measurement platform allows us to circumve...[ Read more ]

The coupling of electromagnetic (EM) radiation to mechanical motion is not only of fundamental interest but is also relevant to practical applications. In this thesis, I will describe experiments investigating the local EM stress on a metamaterial unit. While it is well-known that the EM field is strongly concentrated at resonance and the total EM force can be strongly enhanced from the ordinary radiation force, here we show that the enhancement in the local EM stress is even larger. A general recipe for isolating the EM contribution from photothermal effects will also be described. In another effort, we investigate the strong geometrical dependence of the Casimir force that arises from quantum fluctuations of the EM field. A monolithic measurement platform allows us to circumvent the alignment difficulties in Casimir force measurements. Since two silicon nanostructures can be aligned almost perfectly, we can measure the Casimir force even after their interpenetration. In our experiments, we focused on two kinds of nanostructures. In the first T-shaped structure, we observed a non-monotonic Casimir force. A ‘Casimir spring’ effect analogous to the optical spring in optomechanics is observed. The second structure consists of two interpenetrating gratings. It shows a Casimir force independent of the distance between the gratings. In such a structure, we measure a factor of greater than 500 deviations from the proximity force approximation, the strongest geometry dependence observed so far.