Lasers simply displays Hermite-Gaussian and/or Laguerre-Gaussian laser beam profiles on your screen.
Select the kind of modes with the pop-up menu. Select the number of beam profiles displayed with "# profiles", and the resolution with "Resolution" (1x1 is beautiful, but awfully slow). Check the log scale checkbox to enhance hard-to-see profiles (the profiles are power-normalized).
Of course, you might not appreciate the deep beauty of it all unless you're a laser physicist...