Abstract

We report the recording of holographic relief gratings in dye-in-polymer films previously developed for optical disk applications.¹ Recording was performed with a frequency-doubled Q-switched Nd:YAG laser in a Mach–Zehnder interferometer configuration. Efficiencies in the first diffraction order of 3–4.5% were obtained. Strong diffraction into the second order was observed, which indicates a nonsinusoidal grating profile. We monitored grating formation during writing by means of an auxiliary He—Ne laser. The grating starts forming rapidly after the application of the laser pulse. Diffraction then reaches a maximum, after which the polymer cools off and relaxes to form a permanent grating. The polymer film can be used as the building block for a stratified-volume holographic medium.² We have studied by computer simulation the storage capability of the artificial three-dimensional memory medium. The discrete nature of the medium leads to a multiplicity of Bragg angles in which the separation between peaks is dictated by the interlayer distance, and the width of the peaks is dictated by the overall structure thickness. The number of multiplexed holograms that can be stored and read out unambiguously in a three-dimensional memory application is equal to the number of layers in the structure.

© 1990 Optical Society of America