The Beam Propagation Factor of Nonparaxial Truncated Flattened Gaussian Beams

Abstract

By using the second-order moment of the power density, the beam width, far-field divergence angle and M2 factor of nonparaxial truncated flattened Gaussian (FG) beams are derived analytically. It is shown that the M2 factor of nonparaxial truncated FG beams depends not only on the truncation parameter δ and beam order N, but also on the initial waist-width to wavelength ratio w0/λ. The far-field divergence angle approaches an asymptotic value of θmax=63.435° when the truncation parameter δ → 0. For the special cases of N = 0 and δ → ∞ our results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated FG beams, respectively.