Spiral-galaxies-inspired structured light and optical trapping

Spiral galaxies are the most common type of galaxies in the universe, and most spiral galaxies contain a supermassive black hole in their center. However, thus far, the formation of spiral galaxies is still not fully understood, and especially, what determines the number of spiral arms is still an open question as well. Here, inspired by fascinating spiral galaxies, we demonstrate that such a spiral-galaxy-shaped optical field can be generated by interference of a vortex wave and a trumpet wave. Interestingly, we show it is the topological charge of the vortex wave that determines the number of spiral arms in our model. Moreover, we experimentally trap nanoparticles using the structured light and get a spiral-galaxy-like model in a lab. Lastly, we discuss the origin of the trumpet wave through transformation optics and discuss the similarity between our model and spiral galaxies.