Pushing and pulling optical pressure control with plasmonic surface waves

Abstract

The basis for pulling a passive nanostructured material using laser light by establishing a transverse surface plasmon resonance on the back of a membrane is presented and supported with both theory and numerical simulations. The total force magnitude and direction can be regulated by electromagnetic resonant modes interacting with materials that can be adjusted using the material and geometry variables, and with plane-wave illumination under sinusoidal steady-state conditions. In the situations treated, the structured material is fixed in position and the force density and hence total force are determined numerically. Simulations indicate that a silicon nitride film coated with gold and patterned to produce a unit cell having a slot passing through both materials allows satisfactory surface wave control to facilitate a pulling force with visible wavelengths. When the plasmon surface wave on the back dominates, pulling occurs, and when the mode on the front has more energy, the result is pushing. It is also shown that pushing or pulling, regulated by varying the wavelength of the incident light, is possible, and an example is presented. This work motivates an experimental effort to investigate pulling with nanostructured media and offers a different paradigm in optomechanics.