If I am not mistaken the left figure is just a plot of absorption versus pillar height and wavelength, i.e. there’s no optimizing going on in this plot. If that is all you need, to get the colour plot like this, you just run the sweep and then plot the result (right click on the sweep and click “visualize” and “R”). It’s not clear how the right graph is generated. Probably it is a plot of the maximum absorption for each pillar height. If true, you can either do this at the end once you’ve got the sweep results, or you may be able to calculate it as you are performing the sweep (by adding another parameter to the sweep results, which is the maximum of the reflection in your case).
Before all of that the first step is to get your sweep set up correctly. A tip for this is to right click on the sweep and select “animate”. Currently it is clear that nothing in your simulation changes as you sweep. The pillars are moving apart, yes, but that is all outside of the FDTD region, so these changes are having no affect on the FDTD region and every single sweep gives the same result. Probably what you want to do is to add a new parameter to the sweep, which is the FDTD span in the x direction. (So that the boundary of the FDTD region is always midway between pillars.) This will then keep the symmetry correct and give you the result you want.