Two-dimensional multilevel grating array generators with regular M×N fan-out patterns are designed using both nonlinear optimization and an iterative phase retrieval algorithm. Ten-level designs with fan-out of 2×2, 4×4, 1×8, and 8×8, with design efficiencies of 87%, 92%, 95% and 89% are manufactured using direct electron-beam lithography on electron resist. The measured efficiencies, 79%, 84%, 84% and 84% of transmitted light, respectively, are ~ 10% above the theoretical efficiencies of non-separable binary-phase array illuminators. © 1992.
|Number of pages||5|
|Publication status||Published - 1 Mar 1992|