Storage density and signal/noise ratio in a binary frequency-selective optical memory utilising multistage optical spectral hole burning

The signal/noise ratio (SNR) of a thin-film optical memory with frequency multiplexing, based on multistage optical spectral hole burning, is compared with the SNR expected for single-stage hole burning. The dependences of the SNR on the single-frequency two-dimensional data storage density are obtained for various optical diffraction images in the focal plane. It is shown that a change from single-stage to multistage hole burning provides new opportunities for increasing the basic (in the absence of frequency multiplexing) storage density, which at the 0.5 μm wave-length can reach ~10⁹ bits cm^–2 . When the frequency multiplexing factor is ~10³, the total storage density in two-dimensional carriers can rise to 10¹² bit  cm^–2 .