Holographic formation of optical-vortex filaments

An optical-vortex filament is characterized by a dark core of vanishing size and fluidlike propagation dynamics in the near-field region. This type of phase singularity does not naturally occur as an eigenmode of a cylindrically symmetric system, but it can be easily formed by computer-generated holography. The size of the core is an important attribute affecting vortex–vortex interactions within a laser beam. Here we demonstrate a means to minimize the core size, and we experimentally show that a beam-to-core size ratio exceeding 175 may be readily achieved.