Doping improves holographic storage performance of lithium niobate

Doping improves holographic storage performance of lithium niobate

By manipulating the composition of stoichiometric lithium niobate (LiNbO3) as a material for nonvolatile holographic data storage--and by doping the material with iron and manganese--researchers at Stanford University (Palo Alto, Ca), Optitek (Mountain View, CA), and the Rockwell International Science Center (Thousand Oaks, CA) improved sensitivity, dark storage time, and gating efficiency of the material compared to earlier reports. Based on previous work using a two-photon gated recording method on an undoped, lightly reduced LiNbO3 crystal, the researchers found that two-photon sensitivity had a sharp threshold dependence on material composition near stoichiometry. Consequently, with postgrowth reduction processing, they were able to increase sensitivity by a factor of 20 in undoped LiNbO3. The researchers also investigated transition ions of manganese and iron as extrinsic dopants and found that they could improve both two-photon sensitivity and dark storage times by optimizing the total concentration and reduction state of the dopants. Thus, gating efficiency in stoichiometic, iron-doped material improved by a factor of three over undoped samples. Contact: Lambertus Hesselink at bert@kaos.stanford.gifdu.