Beam propagation factor based on the Rényi entropy

VAVELIUK, P.; LOPES DA SILVA, M.

OPTICS LETTERS

OPTICAL SOC AMER

Año: 2008 vol. 33 p. 2035 - 2037

0146-9592

A beam width measure based on Rényi entropy was introduced by Luis [Opt. Lett31, 3644 (2006)]. That one-dimensional analysis was limited to beam profiles with rectangular symmetry. In this Letter, we derive a general Rényi beam width measure that accounts for the diffraction properties of beams with profiles of arbitrary symmetry. We also show that the square of this measure has a quadratic dependence as a function of the propagation coordinate, so that it can be applied to propagation through arbitrary ABCD paraxial systems. The Rényi beam propagation factor, here introduced, is discussed in examples where the M2 factor seems to have a limited effectiveness in describing the beam spreading.