Evanescent Wave


The team hopes to move on to a more perplexing case. Light striking the boundary between two refractive materials at a sufficiently shallow angle glances off completely as a reflection rather than passing through, but also creates a decaying field known as an evanescent wave on the other side of the boundary. This evanescent wave can reach across a narrow gap and strike up a new light wave in an adjacent medium. Theorists have presented discrepant calculations of how long light takes to traverse such a gap, but Migdall says the new system should be precise enough to measure such transits directly.


National Institute of Standards and Technology (2008, March 17). Speed Of Light: Sub-femtosecond Stop Watch For 'Photon Finish' Races. ScienceDaily. Retrieved March 19, 2008, from http://www.sciencedaily.com­ /releases/2008/03/080313185734.htm