Thanks Steven,
I select “cladding” in the upper pane and “width” in the lower pane, and then set the range of the scanning width from 1 to 1.5 (means 1L to 1.5L). The scanning width equal to 1 means the original width of cladding is not shrunk or expanded. So, the effective refractive index of the cladding modes will not change. However, the calculated effective index of LP02 mode with scanning width equal to 1 is 1.44793 (see Fig. 1) which is smaller than that (1.4627469) without setting the scanning parameters (see Fig. 2).