Data from a cut line with Livelink Matlab

Hello,

I'm studing an optical waveguide in Comsol.
I have defined a cut line 2D to observe the electric field z-component along the width of the waveguide.
Then I have used the livelink matlab command:

mphinterp(model,{'real(ewfd.Ez)'},'dataset','cln1','Solnum','5')

to retrieve the same electric field z-component and plot the corresponding profile.
I have almost the same plot as in Comsol but there are some supplementary points that give the plot a saw tooth like profile.
If I export the data from Comsol into a file and use them to plot the field, I have the same smooth plot as in Comsol but I don't want to loose time exporting the data like this.

What are those supplementary points given by mphinterp? What is the good way to directly retrieve data from a cut line to avoid them?

Thanks in advance!