Multifunctional Optomechanics with Structured Material

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The use of light to control mechanical systems is of broad importance in technology and science. However, planar mirrors experience an optical force only in the direction of the incident light. Consequently, to move such structures in the opposite direction requires a restoring force that may not exist or may not have suitable characteristics. More generally, being able to control the motion of material, depending on the spatial and spectral properties of the incident light, would offer impact in applications as diverse as optical communication and computing and molecular biology. The goal of this project is to investigate the relationship between the strength and direction of the optical force and the nanometer-scale arrangement of material from which the object is made. This is expected to lead to a new class of multi-functional optomechanical components that will allow, for example, remote and energy-efficient control for all-optical data networks, as well as actuators having a wavelength-dependent response. Also, more control over force and torque than exist with current laser beam tweezers will provide for new dimensions in molecular biology. In addition, the project should be important for propulsion because of the possible strength and regulation of the optical force imparted by a laser. Graduate and undergraduate students will be involved in the research and a learning module to excite young people to pursue studies in related disciplines will be developed.This project involves two research topics. The first is the development of a design methodology for optomechanical devices based on metal and dielectric structures that provide pushing (in the direction of the incident beam) and pulling (in the opposite direction) forces. Numerical field solutions yield force density in the material and hence the force and torque on the structure can be determined. This model provides a means for device design. While the primary focus is membrane implementation, generalized principles should ensue. The second topic is the experimental demonstration of key optomechanical device principles. Work with structured films on silicon nitride membranes will lead to implementation strategies with silicon films that will allow large-area devices. The experiments will evaluate pushing and pulling forces, and investigate ways to use the same structure to realize bidirectional forces based on the character of the control light (most simply, wavelength, but potentially the spatial control of the incident light).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.