Abstract

Binary phase gratings, also called Dammann gratings, represent a successful technique to fabricate fan-out elements with good uniformity of the generated array of beams, but moderate efficiency (60 - 70 %). Multilevel phase gratings [1], or smooth surface relief structures [2] have been investigated yielding improved diffraction efficiencies (> 90 %). However, proper modulation at large carrier frequencies (> 1000 lines/mm) is difficult to achieve by mask projection or laser beam writing. Therefore, interferometrically recorded holograms are still of interest for realizing off-axis elements and large fan-out numbers. This paper deals with simultaneous and sequential recording of efficient fan-out elements in thick volume holograms. We have applied coupled wave theory to the special problem of regular fan-out elements.

© 1992 Optical Society of America