Interparticle separation dependent dynamics in optical matter (Conference Presentation)

Abstract

Optical trapping has proved to be a valuable research tool in a wide range of fields including physics, chemistry and material science. The ability to place and manipulate individual colloidal particles in a precise three-dimensional location has been highly useful for the understanding of soft matter phenomena and inter-particle interactions. It also holds great promise for nanoscale fabrication and ultra-sensitive medium sensing by enabling precise positioning of specific material building blocks. An interesting consequence of optical trapping is seen when a large number of particles are trapped in a single holographic trap that is significantly larger than the particle diameter. Due to the interference effects between the incident light and scattered light, the particles become strongly bound to one another. This can lead to the creation of large, highly ordered structures of colloidal particles, termed optical matter. The geometry of the structure is dependent on the phase and polarization profile of the incident optical beam. In this talk we discuss our research on the structural and dynamical effects on optical matter composed of plasmonic nanoparticles. We describe how the structures are formed from one particle up, and how their dynamics and structure are shaped by the size, phase profile, and polarization of the incident optical beam. Specifically we discuss how circular polarization can create an isotropic optical binding potential and induce rotation in the system, and how the rotation depends on the particle and beam characteristics.