Nano-architected material refracts light backward; an important step toward creating photonic circuits

https://phys.org/news/2022-01-nano-architected-material-refracts-important-photonic.html

"Each cube is so tiny that the width of the beams making up the cube's structure is 100 times smaller than the width of a human hair... polymer coated evenly at that scale with a metal required the research team to develop a wholly new method... sputtering technique in which a disk of germanium was bombarded with high-energy ions that blasted germanium atoms off of the disk and onto the surface of the polymer lattice... telecommunications, medical imaging, radar camouflaging, and computing"

Related: This Mirror Reverses How Light Travels in Time
https://spectrum.ieee.org/time-reversal-interface