We have investigated the crosstalk between two neighboring gratings in photorefractive Bi12SiO20 optical interconnects. The gratings are induced by the interference between one reference beam and two object beams. By applying a suitable phase shift in one of the object beams, we can selectively switch off one of the gratings. The crosstalk between the two gratings is experimentally determined from the diffraction efficiency in the remaining grating before and after applying the phase shift. The magnitude of the crosstalk is determined by the intensity ratio between the reference beam intensity and the object beam intensity. Crosstalk can be avoided by choosing a certain intensity ratio between the reference and the object beams.