Holographic fixing with modulated light in two-center holographic recording

摘要

The two-center holographic recording method is a very effective technique to realize nonvolatile photorefractive holographic storage in doubly-doped LiNbO3 crystals, but its main drawbacks are low fixing diffraction efficiency and low recording sensitivity, Commonly homogeneous readout light was used to fixing holographic grating, because the concentration of donor in shallower center had a nearly 180° phase difference to space-charge field at the end of recording phase, a negative photovoltaic field should be created and drive part of electrons come back to its origin position, finally low the fixing space-charge field In this paper a new fixing method for two-center holographic recording was proposed, and the modulated light with the same optical phase to recording light is used to fix holographic, The new formed photovoltaic field has the same phase with recording light and counteracts with the negative photovoltaic field, finally heavily enhance the fixed space-charge field. Furthermore, the recording sensitivity can be markedly increased with higher intensity ratio of recording light to sensitizing light, at the cost of a little decrease in fixed space-charge field.