Wavelength-multiplexed volume holograms for fully interconnected neural networks
Robert T. Weverka, Kelvin H. Wagner, Mark E. Saffman · Optical Society of America Annual Meeting · 1990
The degrees of freedom available in a three-dimensional volume hologram only permit interconnection between sparse fractal planes1 of optical neurons that do not adequately sample dense two-dimensional images. We are investigating the capabilities of spectral-hole-burning volume holography2 for implementing N 2 to N interconnections, and will present several approaches for using the wavelength domain as the necessary extra dimension. Global interconnection architectures based on N wavelength-multiplexed N-to-N 2 mappings do not produce any unwanted Bragg degenerate diffractions, but those based on N 2 -to-N mappings produce unwanted diffractions that can be eliminated with a spatially dependent wavelength filter, such as a wedged Fabry-Perot étalon. Other architectures based on N 3/2 -to-N 3/2 mappings with N multiplexed wavelengths to achieve N 2 -to-N 2 global interconnections as well as local mappings requiring fewer wavelengths are also possible. These schemes access all of the degrees of freedom of a spectral-holeburning hologram simultaneously, allowing as many as 1012 multiplications per readout, and learning architectures allow these interconnections to be adaptively modified based on a sequence of training patterns.