Fractional Talbot four-level phase-only holograms using ferroelectric liquid-crystal spatial light modulators

We propose a new technique for generating a four-level reconfigurable phase-only hologram, using two binary phase {0,pi} ferroelectric liquid-crystal spatial light modulators. The principle is based on the self-imaging properties of periodic structures operating in a Fresnel field double-diffraction system. Fractional Talbot planes are shown to be of particular interest. The problem of hologram bandwidth reduction that results from the holographic pattern replication is addressed. A trade-off between diffraction efficiency and hologram coding capacity is considered.