CST2013: Solver / Generate Gaussian Beam

Home: MacrosMacrosSolverGenerate Gaussian Beam as Field Source

Use this macro to generate a Gaussian Beam via the near field source functionality.

Beam parameters:

Wavelength: The wavelength lambda (in nm) of the beam

Focus distance: Distance (in project units) between the source center and the focus point of the beam (point of smallest diameter). The source will be of cuboid shape.

Rayleigh length (alternatively: minimum beam width):

The Rayleigh length z_R determines the distance (in project units) over which the beam can be considered as focused. The minimum beam width w0 is the beam diameter in the focus point. The two quantities are related via z_R=w0^2*Pi/lambda. The physically smallest possible beam width is 2*lambda/Pi^2, which is equivalent to a minimum Rayleigh length of 4*lambda/Pi^3.

Orientation and polarization:

Propagation vector: The x/y/z components of the beam propagation vector.

Source center: The x/y/z coordinates (in project units) of the center point of the cuboid representing the near field source.

E-field polarization angle: By default, for a beam propagating in z direction, the main component of the E field is directed in x. Use

this angle to rotate the fields around the beam axis. When looking in the direction of propagation, positive angles describe a

counter-clockwise rotation.

Miscellaneous:

Truncation error: The beam amplitude in radial direction decays exponentially but never reaches a true zero. Since the source size has

to be limited, the amplitude will be truncated at some point. This number determines how much of a truncation error the user is willing

to accept. This setting directly influences the size of the source box, small truncation errors (<1e-6) can result in very large sources.

Lines per wavelength: This number determines the number of samples on the source surface. Values of 8 and above are recommended to accurately render the fields.

OK:

Generates the beam. The source file will be copied into the model3D subfolder of the project folder and the near field source will

automatically be imported. The macro will also set up E and H field monitors at the frequency corresponding to the beam's wavelength.