Deep learning optimized isotropic diffractive layers focus unidirectional light forward, suppressing unwanted backward focusing

https://phys.org/news/2025-03-unveil-unidirectional-focusing-diffractive-optics.html

"compact, broadband... no: costly, bulky specialized material properties/ nonlinear materials, high-power laser sources, need for active modulation, polarization/ wavelength sensitivity, diagonal illumination issues... 3D printed 2-layer diffractive structure that unidirectional focused THz... signal efficiency, security, clarity, reduced background interference... free-space optical links, imaging and sensing, laser machining, biomedical, metrology, security, defense, optical communications"