13 Facts About Gaussian beam

In optics, a Gaussian beam is a beam of electromagnetic radiation with high monochromaticity whose amplitude envelope in the transverse plane is given by a Gaussian function; this implies a Gaussian intensity profile.

The electric and magnetic field amplitude profiles along any such circular Gaussian beam are determined by a single parameter: the so-called waist.

At any position relative to the waist along a Gaussian beam having a specified, the field amplitudes and phases are thereby determined as detailed below.

Geometric dependence of the fields of a Gaussian beam are governed by the light's wavelength and the following beam parameters, all of which are connected as detailed in the following sections.

At a distance from the waist equal to the Rayleigh range, the width of the Gaussian beam is larger than it is at the focus where, the Gaussian beam waist.

That point along the Gaussian beam happens to be where the wavefront curvature is greatest.

Divergence is inversely proportional to the spot size, for a given wavelength, a Gaussian beam that is focused to a small spot diverges rapidly as it propagates away from the focus.

Since the Gaussian beam model uses the paraxial approximation, it fails when wavefronts are tilted by more than about 30° from the axis of the beam.

The BPP of a real Gaussian beam is obtained by measuring the Gaussian beam's minimum diameter and far-field divergence, and taking their product.

Numerical aperture of a Gaussian beam is defined to be, where is the index of refraction of the medium through which the beam propagates.

The Gaussian beam solution is valid only in the paraxial approximation, that is, where wave propagation is limited to directions within a small angle of an axis.

The fundamental Gaussian beam happens to be the one that minimizes the product of minimum spot size and far-field divergence, as noted above.

The effect of the rotational mode number, in addition to affecting the Laguerre polynomial, is mainly contained in the phase factor, in which the Gaussian beam profile is advanced by complete phases in one rotation around the Gaussian beam (in ).