Two-center holographic recording in highly doped LiNbO3 crystals

In this paper, we report the observation of electron tunneling during two-center recording in LiNbO₃:Fe:Mn doped with high Fe concentration. Unlike tunneling in the singly doped lithium niobate that erases the hologram, the effect in two-center recording can improve the diffraction efficiency of the hologram after the recording while it is kept in the dark. A detailed study of this effect in LiNbO₃:Fe:Mn is presented both theoretically and experimentally. We show that the hologram strength may increase or decrease due to tunneling, depending on the experimental condition of recording. PACS 42.40.-i; 42.70.Ln; 42.40.Lx