Multiphoton photorefractive processes for optical storage in LiNbO3

Abstract
Permanent reversible changes of the refractive index of pure and doped LiNbO3 have been obtained by multiphoton absorption. Greatly increased sensitivity over the linear process enables holograms to be recorded even in high‐purity LiNbO3, with a diffraction efficiency of 25% with less than 0.4 J/cm2. These holograms can be read nondestructively, eliminating the need for fixing processes while the versatility of optical erasure is maintained.