Influence of an externally applied magnetic field on vectorial interaction in LiNbO₃:Fe crystals

An experimental investigation of the influence of an externally applied magnetic field on the dynamic grating formation in iron-doped lithium niobate is carried out. The diffraction efficiency and the two-beam gain depends strongly on the applied magnetic field. We observe changes in the two-beam gain and the diffraction efficiency of up to 40 and 75 %, respectively. The magnitude depends on the direction of the magnetic field. The interaction is believed to occur due to the anomalously high mobility of the nonthermalized free electrons responsible for the photovoltaic current, which in the vectorial interaction scheme causes the grating formation. A phenomenological description of the photovoltaic current including the photo-flail effect shows a linear dependence on the magnetic field, which does not explain the obtained experimental results.