ABSTRACT
Advances in fabrication technology have led to a greater appreciation for the limitations of scalar diffraction theory for analysis and design. The proper design of elements whose features are less than or on the order of a wavelength requires tools that can analyze and design arbitrary elements using rigorous vector-based diffraction theory. Since the 1980s, considerable progress has been made in the rigorous analysis and design of diffractive optical elements. One of the most significant results has been the high-diffraction efficiencies produced by binary diffractive elements that have subwavelength features. In fact, the presence of only a few subwavelength features is sufficient to increase diffraction efficiency.
