Photoinduced linear dichroism in sillenite crystals and in diamond

By illumination with linearly polarized light, a strong optical linear dichroism (LD) can be created in undoped sillenites of the type Bi12TiO20(BTO). This photoinduced LD is stable in the dark at T < 77 K and is reversible by changing the direction of the polarization appropriately. The spectra of the LD and of the magnetic circular dichroism (MCD) of the Bi-Ti(4+) antisite reveal some similarities; however, there is no direct evidence for attributing the LD to Bi-Ti(4+). The observation of the LD as a function of the direction of the polarization is shown to give information on the symmetry of the center causing the LD. Comparative studies of nitrogen containing diamond support this fact.