HOLOGRAPHY IN FREQUENCY SELECTIVE MEDIA .2. CONTROLLING THE DIFFRACTION EFFICIENCY

A novel hologram storage technique based on recently reported causality effects in spectral hole-burning media [1] is presented. Simultaneously sweeping the phase and frequency of CW recording light produces holograms with new diffraction properties. In particular the distribution of the light in the different diffraction orders becomes asymmetric and can be easily controlled by the direction of the phase shift. The line shape of phase and frequency swept holograms can be designed in a way which yields many advantages for optical data storage. Compared with normal holograms recorded at a single frequency the maximum diffraction efficiency has been increased by a factor of 5.