Constant ring width of the Laguerre-Gaussian vortex beams

We studied ring width of the Laguerre-Gaussian vortex beams, which is the outer radius minus the inner radius. Combining theoretical analysis and numerical simulation, the approximate expression of the ring width is obtained. From the expression, we find that the ring width is independent of the topological charge, and increases with the increase of the waist radius at z=0 of the host Gaussian beam and the propagation distance. This research has good application prospects in optical tweezers technology and OAM optical communication.