3D-printed diffractive terahertz optical elements through computational design

Abstract

This manuscript reviews our previously reported progress on the computational design of terahertz diffractive optical elements (DOEs). A scalar diffraction approach is advantageous due to its ease of modeling and fabrication which renders it to be ultra-thin (1.5-3λ0), and relatively error-tolerant. In the recent past, there have been several reports in the literature on the design and fabrication of various terahertz DOEs; primarily; in the area of diffractive terahertz lens design, where a demonstration of compact, large aperture, and aberration-free lenses had already been shown. However, the biggest challenge is the lack of a systematic framework towards the design of DOEs at terahertz wavelengths. In this manuscript, we highlight our recent findings on that by enabling a computational design -based approach towards the modeling of terahertz DOEs; optimal DOE solutions with reduced (up to > 10X-100X time faster convergence) computational costs are indeed possible. This is enabled by the careful utilization of a robust scalar diffraction -based wave propagation model in combination with an optimization-based search algorithm; namely, the Gradient Descent Assisted Binary Search (GDABS) algorithm.