Yes.  But at some dimensions of the waveguide, it only supports the fundamental mode. As with the FDE solver, I found that the only supported mode below 230nm diameter of the waveguide is the fundamental mode. Higher order modes appear after that.

So, the dipole should radiate in the fundamental mode only for a diameter below 230 nm. So, the transmission corresponds to the power monitor which basically gives T_total should be equal to the T_forward which is basically the power radiated only by the fundamental mode. But I am getting minimum transmission corresponding to the fundamental mode in these regions. Also, the data set is not consistent. It's like it is picking some random number between 0.01 to 0.4.