Poynting vector and beam divergence

摘要

Laser beam divergence was considered using the components of the Poynting vector. A physical interpretation of the real and imaginary parts of the "longitudinal" field component (along the z axis, the direction of beam propagation) is given in an exponential representation. The longitudinal field component was shown to be the reason for the formation of laser beam divergence. This fact was used to reveal fundamental differences between Laguerre-Gaussian beams and incoherent rays in the focal region. The possibility of using selective action on the longitudinal field component to decrease the divergence of Laguerre-Gaussian beams is discussed. (C) 2020 Optical Society of America