Optical Force Regulation with Nanostructured Materials
Abstract
The use of light to control mechanical systems is of broad importance in science and technology. From Maxwell’s theory, the maximum optical pressure on a mirror is twice the average incident power density divided by the velocity of light. Here it is experimentally demonstrated that, with a specially designed nanostructured membrane, the optical pressure substantially exceeds that on a perfect mirror. Enhanced pressure is demonstrated by deflection measurement of a patterned gold film on a silicon nitride membrane, in conjunction with a model and with established error bounds to draw definitive conclusions. The enhancement of the net optical pressure with nanostructured material over that on a perfect mirror can be understood as being due to an asymmetric cavity effect within a modest quality factor regime, and this is illustrated using a simple one-dimensional model. Therefore, carefully harnessing the photon confinement in nanostructured material leads to pressure enhancement. The physical basis of a net pulling force on a structure is presented. Whether there is a pushing or a pulling pressure can be regulated by excitation of a surface wave on the front or back side of a nanostructured metal film. This can be achieved through geometrical and material design, and it is shown that pushing or pulling with a single structure, depending on wavelength, is possible. Furthermore, an enhanced pulling pressure can also be achieved in a simple all-dielectric silicon-based system. Various applications will benefit from optomechanics with pushing or pulling achieved by control of the characteristic of the incident light.
Degree
Ph.D.
Advisors
Webb, Purdue University.
Subject Area
Electromagnetics|Mathematics|Nanotechnology|Optics|Physics
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