Multifrequency Bessel beams with adjustable group velocity and longitudinal acceleration in free space

The group velocity of an optical beam in free space is usually considered to be equal to the speed of light in vacuum. However, it has been recently realized that, by structuring the beam's angular and temporal spectra, one can achieve well pronounced and controlled subluminal and superluminal propagation. In this work, we consider multifrequency Bessel beams that are known to propagate without divergence and show a variety of possibilities to adjust the group velocity of the beam by means of designed angular dispersion. We present several examples of multifrequency Bessel beams with negative and arbitrary positive group velocities, as well as longitudinally accelerating beams and beams with periodically oscillating local group velocities. The results of these studies can be of interest to scientists working in the fields of optical beam engineering, light amplitude and intensity interferometry, ultrafast optics, and optical tweezers.

Automated summary

It has been discovered that the group velocity of an optical beam can be adjusted by designing the angular dispersion, including achieving subluminal and superluminal propagation as well as periodic oscillation of local group velocities. These findings are of great importance to scientists in the fields of optics, optical interferometry, and more.