Highway Ramp for Light (IMAGE) University of California - Berkeley Caption Each individual "light switch" is constructed like a microscopic highway overpass. When the switch is off, the light passes straight through a lower channel (red lines). Turning the switch on lowers a tiny ramp, directing the light to an upper channel to make a right turn (blue lines). A second ramp lowers the light back down. Credit Tae Joon Seok image Usage Restrictions with credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.