Leonard Huxley Lecture Theatre
Dr Anton Desyatnikov
Nonlinear Physics Centre
Optical vortex is a name for the twisted flow of light around dislocation in a phase front of a laser beam. Optical vortices arise naturally as the dark spots at the points of total destructive interference within diffraction patterns, speckle fields and various natural optical phenomena. In three spatial dimensions the phase singularities follow complex trajectories forming vortex lines, the ‘’threads of darkness’’, which can be linked and knotted. We are interested in the nonlinear dynamics of optical vortices, similar to quantised vortices in atomic and polariton Bose-Einstein condensates, and I will discuss recent theoretical and experimental results on the dynamics of optical vortices embedded in laser beams propagating in self-focusing media. I will focus on the spontaneous knotting of optical vortices in nonlinear media. In contrast to linear optics, our recent theoretical studies of the field topology of a simple fundamental soliton perturbed by various initial deformations, such as twist, shows the spontaneous formation of vortex loops, spirals, and more complex links and knots. A small variation of parameters leads to vortex line reconnections, transforming and destroying knots as well as forming new knots. The vortex knots are thus unstable, yet their spontaneous appearance suggests that wave knotting is a robust nonlinear phenomenon.
ABOUT THE SPEAKER:
Dr Anton S Desyatnikov graduated (1998) and got his PhD (2000) from Moscow Engineering Physical Institute and he completed the Alexander von Humboldt research fellowship (2002-2003) in Muenster University, Germany, before moving to ANU as a research fellow (2004). Dr Desyatnikov was awarded the Australian Research Fellowship in 2007 and he currently works in the field of nonlinear photonics and singular optics, including optical vortices and vortex solitons, angular momentum and topological transformations of light.