The rotation of a constellation is due to a change in phase of all symbols. This could mean propagating down the length of a fiber or due to dispersion. The smearing of the individual symbols is also a phase effect, which without looking at your design I would assume is from dispersion as well or possible SPM. The CW Laser also introduced phase error from its linewidth.
The OFDM demodulator component is able to efficiently correct this issue with carrier phase estimation from the pilot tones, but the older OptiSystem 12 components do not have this functionality.
Regards