Focusing properties of high charge number vortex laser beams.
We investigate experimentally and numerically the propagation characteristics of laser beams formed by imparting an azimuthal phase lphi to a Gaussian beam, where l is an integer. We find that when high-l beams of a finite extent are focused through a lens, the beams achieve peak intensity and are most sharply defined before and after the focal plane. Additionally, in these regions of highest intensity the effect of aberrations on the beam quality is greatly reduced, which we also demonstrate experimentally and numerically. We present a simple geometrical picture that provides excellent estimates of the beam radius and propagation distance to the plane of peak intensity.
Fatemi
Fredrik K
FK
Optical Sciences Division, Naval Research Laboratory, Washington, DC 20375, USA. ffatemi@ccs.nrl.navy.mil
Bashkansky
Mark
M
D003198:Computer Simulation; D004867:Equipment Design; D007834:Lasers; D008027:Light; D015233:Models, Statistical; D008962:Models, Theoretical; D016011:Normal Distribution; D055095:Optics and Photonics