Electromagnetic vortices are naturally occurring throughout the universe and have recently been observed in association with black holes. Over the last decade, scientists have sought methods to investigate how extremely strong electromagnetic vortices interact with matter, specifically plasma, in a laboratory setting.
Plasma, known as the fourth state of matter, makes up nearly all observable matter in the universe and consists of freely moving ions and free electrons. The use of high-intensity lasers to generate these vortices have shown great promise and have the potential to unlock new physics when such beams interact with plasma.
Andrew Longman, a High Energy Density Science (HEDS) Center postdoctoral fellow for Lawrence Livermore National Laboratory, proposes that spiral phase mirrors, when incorporated into a laser system, will enable scientists to “twist” the laser light and generate an optical vortex. An optical vortex is best described as a beam with a helical wavefront, like a whirlpool but spinning at the speed of light. Optical vortices are best described as a beam with a helical wavefront. In Andrew Longman’s research, optical vortices are used to rotate plasma to extremely high angular speeds, enabling studies of new physical phenomena. To generate these vortices at ultra-high intensities, Longman uses an off-axis spiral phase mirror—a mirror that has a wavelength-deep (less than one-thousandth of a millimeter) spiral imprinted on its surface.