Bessel-like beams with z-dependent cone angles

Abstract

A new type of Bessel-like optical beams, which is distinguished by the dependence on the cone angle from the longitudinal coordinate, is investigated. Such beams have the properties of Bessel beams (ring-spatial spatial spectrum) as well as Gaussian beams (keeping the transverse profile at any distances). This new type of beams can be obtained in optical system composed of lens axicon doublet and conical lens. An experimental set-up for producing such beams is realized. It is shown that depending on its parameters the scheme allows one to produce z-dependent Bessel-like beams, whose spatial spectra change from Bessel function to shifted Gaussian one. It is establish theoretically and confirmed experimentally that on-axial intensity of z-dependent Bessel-like beam could be higher than that of incident Gaussian beam.