Simulation of near-diffraction- and near-dispersion-free OAM pulses with controllable group velocity by combining multiple frequencies, each carrying a Bessel mode

Optical pulses carrying orbital angular momentum (OAM) have recently gained interest. In general, it might be beneficial to simultaneously achieve: (i) minimum diffraction, (ii) minimum dispersion, and (iii) controllable group velocity. Here, we explore via simulation the generation of near-diffraction-free and near-dispersion-free OAM pulses with arbitrary group velocities by coherently combining multiple frequencies. Each frequency carries a specific Bessel mode with the same topological charge (l) but different k(r) (spatial frequency) values based on space-time correlations. Moreover, we also find that (i) both positive and negative group velocities could be achieved and continuously controlled from the subluminal to superluminal values and (ii) when the l is varied from 0 to 10, the simulated value of the group velocity remains the same. However, as the l value increases, the pulse duration becomes longer for a given number of frequency lines. (C) 2021 Optical Society of America

Automated summary

By coherently combining multiple frequencies, near-diffraction-free and near-dispersion-free OAM pulses with arbitrary group velocities have been generated. It has been found that both positive and negative group velocities can be achieved and continuously controlled, and that the simulated value of group velocity remains the same when the topological charge l is varied. However, as the l value increases, the pulse duration becomes longer for a given number of frequency lines.