Waveguide hologram for outcoupling and simultaneous focusing into multiple arbitrary positions

Outcoupling waveguide holograms are gratings with locally dislocated grating lines etched into the waveguide surface. They couple light out of the waveguide into air and simultaneously provide focusing capabilities. Here, we present a waveguide hologram that focuses light into spots in any desired three-dimensional configuration. The hologram is fabricated on an InGaAsP-InP waveguide for 1550-nm optical wavelength. In an experiment we obtained simultaneously focused spot patterns at 1.5, 3 and 40 mm distance from the waveguide surface. The uniformity error was 23%, 8%, and 16%, respectively, for the three patterns and the diffraction efficiency was 40%.