Diffraction efficiency of non-uniform gratings in a Bi12SiO20 crystal for a non-linear regime under an external d.c. field

We assess the influence of the non-uniformity of a recorded grating on the prediction of the diffraction efficiency taking into account optical activity, absorption of light, birefringence, polarization angle of the incident beam and an external d.c. field. The influence is noteworthy for samples larger than 3 mm.