Refraction—the bending of light as it passes through different media—has long been constrained by physical laws that prevent independent control over how light waves along different directions bend. Now, UCLA researchers have developed a new class of passive materials that can be structurally engineered to “program” refraction, enabling arbitrary control over the bending of light waves.

In a study published in Nature Communications, a team led by Dr. Aydogan Ozcan, the Chancellor’s Professor of Electrical & Computer Engineering at UCLA, has introduced a novel device called a refractive function generator (RFG) that can independently tailor the output direction of refracted light for each input direction. This device allows light to be steered, filtered, or redirected according to custom-designed rules—far beyond what standard materials or traditional metasurfaces can achieve.

Standard refraction, described by Snell’s law, links the input and output directions of light using fixed material properties. Even advanced metasurface designs only allow limited tunability of refraction.