Investigation of a Reflective Counter-Propagating Holographic Setup

Abstract

A reflective counter-propagating holographic setup for optical data storage is presented. The system makes efficient use of the laser light by using the reference beam to generate the signal beam. After passing through the holographic medium, the reference beam is sent onto a spatial light modulator that directs the modified reference beam back into the holographic medium, where it interferes with the original reference beam. Thus 100% of the available laser power can be used for the reference beam. Furthermore, a special random phase mask and a corresponding data page format are introduced. The phase mask has an improved alignment tolerance of ±0.5 pixels in contrast to a conventional binary phase mask that has a tolerance of only ±0.1 pixels. Moreover, the mask still improves the shift-selectivity and eliminates the strong intensity peak in the Fourier plane. We investigate the shift selectivity and compare experimental and simulated results that were obtained with a two-dimensional fast-Fourier-transform (2D-FFT) volume integral method.