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Digital Planar Holography

Digital Planar Holography (DPH) is a new technology, developed recently for fabricating miniature components for integrated optics. The essence of the DPH technology is embedding digital holograms, calculated in a computer, inside a planar waveguide. This allows for light propagation in the hologram plane rather than in the perpendicular direction and results in a long interaction path. Benefits of a long interaction path are well known for volume/thick holograms . On the other hand planar configuration provides easy access to the surface, where the hologram should be embedded.
As it is well known, light can be confined in waveguides by a refractive index gradient. Light propagates in a core layer, surrounded with a cladding layer(s), which should be selected the core refractive index Ncore is greater than that of cladding Nclad : Ncore > Nclad. Cylindrical waveguides (optical fibers) allow for one-dimensional light propagation along the axis. Planar waveguides, fabricated by sequential depositing flat layers of transparent materials with a proper refractive index gradient on a standard wafer, confine light in one direction (axis z) and permit free propagation in two others (axes x and y).