Numerical evaluation of multilayer holographic data storage with a varifocal lens generated with a spatial light modulator

A multilayer recording using a varifocal lens generated with a phase-only spatial light modulator (SLM) is proposed. A phase-only SLM is used for not only improving interference efficiency between signal and reference beams but also shifting a focus plane along an optical axis. A focus plane can be shifted by adding a spherical phase to a phase modulation pattern displayed on a phase-only SLM. A focal shift with adding a spherical phase was numerically confirmed. In addition, shift selectivity and recording performance of the proposed multilayer recording method were numerically evaluated in coaxial holographic data storage.