Nonvolatile two-color holographic recording in Er-doped LiNbO3

We demonstrate nonvolatile two-color holographic recording in as-grown and reduced Er-doped LiNbO3. It is found that, unlike the case of near-stoichiometric LiNbO3 reported previously, the diffraction efficiency can be increased by a factor of similar to5 after the reduction treatment. The recording sensitivity and the figure of merit M/# for the reduced crystal are measured to be 9 x 10(-4) cm/J and 0.02, respectively, with a 488-nm gating beam at an intensity of 1 W/cm(2) and 780-nm writing beams at a total intensity of 2 W/cm(2). Results of the light-induced absorption measurement suggest that the small polarons are responsible for the two-color photosensitivity in Er-doped LiNbO3.