Researchers use sound to slow down, speed up, and block light

How do you make an optical fiber transmit light only one way? Researchers from the University of Illinois at Urbana-Champaign have experimentally demonstrated, for the first time, the phenomenon of Brillouin Scattering Induced Transparency (BSIT), which can be used to slow down, speed up, and block light in an optical waveguide. The BSIT phenomenon permits light to travel in the forward direction while light traveling in the backward direction is strongly absorbed. This non-reciprocal behavior is essential for building isolators and circulators that are indispensible tools in an optical designer's toolkit.