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GaussianCwLaser models a continuous-wave laser source with a Gaussian beam profile. The source is modeled as single line (wavelength), single mode with specified power. The beam size is specified by the parameter sigma, which is the 1/e radius in amplitude of the Gaussian profile, or equivalently, the 1/e^2 radius in irradiance. That is, if r is the radial coordinate, GaussianCwLaser outputs the amplitude A(r) = A0*exp[-(r/sigma)^2] .
The irradiance, I(r) = A(r)^2 , will have units of W/m^2.
The phase of the output beam is planar, with zero tilt.
The beam is clipped by a circular aperture and/or a circular inner obscuration, and the integral under the CLIPPED Gaussian corresponds to the specified total power (i.e., determines A0 in the profile formula). Note that the clipping aperture radius of the source may be set to an arbitrarily large value to correspond to an unobstructed beam (although this will necessarily leave a small but non-zero irradiance at the edge of the propagation mesh). The Gaussian beam function is defined on the full propagation mesh, with zeros beyond any clipping radius.
Finally, note there are two parameters marked "NOT USED, BUT must be set": these are present for historical reasons and will be removed from the interface in the future. They must still be set, even though they are not used, because all parameters must be assigned values.