In a 2D axisymmetric geometry, the position and orientation of the Gaussian beam is more restricted compared to 2D and 3D geometries. The beam must be symmetric about the z-axis or else it would not actually be a Gaussian beam in the 3D volume of revolution.
Enter the Beam waist z-coordinate zw (SI unit: m). The default is 0. Then, from the Beam direction list, select Positive z-axis (the default) or Negative z-axis.
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Point source (small Rayleigh range), the default, is appropriate when the rays in the model propagate very large distances compared to the beam waist radius or Rayleigh range. The beam waist is treated as a point source, from which rays emanate outward in a cone. The symmetry axis of the cone is the Beam axis from the previous section.
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Collimated source (large Rayleigh range) is appropriate when the rays propagate for only a short distance compared to the Rayleigh range. The rays are released from a grid of points and initially propagate in the same direction.
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Specify beam divergence half-angle (the default), then enter a value or expression for the Beam divergence half-angle α (SI unit: rad). The default is 1 mrad.
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Specify beam waist radius, then enter a value or expression for the Beam waist radius w0 (SI unit: m). The default is 1 mm. In 2D, this option is instead called Specify beam waist half-width and the input is called the Beam waist half-width because the 2D beam is uniform in the out-of-plane direction, not rotationally symmetric about the beam axis.
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Specify Rayleigh range, then enter a value or expression for the Rayleigh range zR (SI unit: m). The default is 1 mm.
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Specify total beam power (the default), then enter a value or expression for the Total source power Psrc (SI unit: W). The default is 1 W.
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Specify encircled power, then enter a value or expression for the Encircled power Pcir (SI unit: W). The default is 1 W.
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Specify Intensity at beam waist, then enter a value or expression for the Peak intensity at beam waist I0 (SI unit: W/m2). The default is 1 W/mm2.
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Components of the Initial polarization reference direction u (dimensionless). By default the vector points in the positive y direction. This must not be parallel to the beam axis.
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Initial polarization, out of plane (dimensionless, default 0).
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