Diffraction efficiency of quantized programmable phase elements: a critical assessment

The combined effect of phase quantization, diffractive element feature size and signal location in the reconstruction plane, on diffraction efficiency upper bounds is presented. An upper-bound criterion linking these different features is given. The interest of such a criterion, regarding the optimization of diffraction efficiency in unconventional cases involving considerations of technical feasibility and system parameters, is discussed. Particular attention is paid to multilevel programmable phase elements involving particular constraints on feature size and phase quantization.