Holographic gratings of different periods were recorded in the photopolymer by two laser beams with opposite circular polarization and a nematic liquid crystal was brought in contact with them. The anchoring conditions for the nematic were modulated in a similar way and an induced, field controlled replica manifested a characteristic asymmetric diffraction for the beams of opposite circular polarizations with dramatically enhanced diffraction efficiency. In fact the situation is more complicated than expected and our modelling of the director distribution for a finite anchoring strength explains the experimental data by considering an additional modulated structure at the polymer-nematic interface.