Unidirectional imaging technology enables efficient/ compact asymmetric visual information processing/ optical communication.

 https://www.eurekalert.org/news-releases/1063040

"forms images from 1 field of view to another, while blocking image formation in reverse direction... work exceptionally well under partially coherent light (where some degree of phase correlation)... high quality and high power efficiency... spatially engineered asymmetric linear diffractive layers optimized for partially coherent illumination... imagers are compact, <75X wavelength of light in thickness... independent of light polarization... compatible with various light sources including broadband radiation"