A continuous laser with uniform intensity distribution

[Hatisa]

I need to simulate a continuous laser with a spot radius of 2.5 micrometers, and its spatial intensity distribution is uniform. How should I set it up?


I have tried to change the x_spot but it doesn't work.
laser intensity a = (e * sqrt((Ey+Bz).^2 + (Ez-By).^2))/(2 * m_e * c * omega_L)
The results I run are as follows:

I need a continuous laser like this:

Thanks!

[Status-Mirror]

Hi @Hatisa

Your laser wavelength is 1 micron, and your profile is 2 microns - such a laser pulse will not physically propagate the way you want it to.

Lasers move through space by following Maxwell's equations. If you set up a profile like you describe, where the beam size is comparable to the wavelength, then the kind of diffraction you observe is guaranteed - this is what Maxwell's equations produce.

To enforce a fixed intensity over some distance, you might want to consider using a 1D simulation - these are diffraction-free, as there is no variation in the $y$ direction.

If it's important that the beam has a set size at a particular point in space (e.g. a laser with a 2 micron spot-size when it hits the target), then you can use a focusing Gaussian beam.

Hope this helps,
Stuart