Design and Analysis of Fixed Planar Holographic Interconnects for Optical Neural Networks

this paper, this technique is referred to as a preconditioned random search. Preconditioned random search was applied to holograms produced by using either the error-diffusion technique or the Gerchberg-Saxton technique. Once a binary transmission hologram has been calculated, it can be fabricated by using electron-beam lithography. The lithographic mask can function as the hologram, or it can be used to copy the hologram to another substrate. Binary phase holograms, which have improved diffraction efficiency relative to binary amplitude holograms, can be constructed from binary amplitude holograms by using reactive ion-etching techniques. The Gerchberg-Saxton, simulated annealing, and random -search techniques can be reformulated to calculate multilevel phase-only holograms. The former is modified by replacing the amplitude quantization function with a phase quantization function, 28 while the pixel update processes of the latter two are modified so that when a pixel is randomly chosen, its discrete phase value is randomly changed to another discrete phase value. The production of multilevel phase-only holograms is more complex than the production of binary holograms. The fabrication process begins by breaking the phase levels into binary values and generating a separate electron-beam mask for each bit. 29 M electron-beam masks are used to generate 2 M phase levels. As with the binary phase hologram, the mask pattern is copied to a substrate and reactive ion etching is used to produce specific phase modulations. This is repeated for all M masks. 4. Hologram Analysis To evaluate the various design techniques, a 64-point connection pattern was defined. Half the interconnection weights in this pattern had a value of 1 and half had a value of 0. With randomness in the desi..