The more intense that laser pulses can be made, the more surprising and extreme are the interaction effects researchers are seeing — effects that are sometimes hard to control. One way to guide or redirect the physics relationships is to manipulate the composition or shape of targets. Nickel nanowires present >95% optical absorption into an effective skin-depth that is very long, greater than 1 μm. Partly this is due to the strong optical anisotropy of these oriented nanostructures: a dielectric in the transverse direction and a conductor along the optical axis. Under intense irradiation, and especially at relativisitic optical intensities, this can lead to transition from dielectric to conductor, strong J×B effects, nonlinear acceleration of electrons and the generation of high harmonic radiation. I’ll outline our new theoretical and experimental results for intensities from small-signal up to very clean relativistic pulses.
Department of Physics & Institute for Optical Sciences, University of Toronto