Researchers demonstrate first echoless light

New Scientist : Waves scatter as they pass through a medium. In communications, that scattering causes parts of a transmitted signal to arrive after the main pulse, which leads to distortion and degradation. In 1948 Leonard Eisenbud proposed a technique to shape pulses to overcome the distortion. Now, Joel Carpenter of the University of Queensland in Brisbane, Australia, and his team have become the first to demonstrate the technique in practice. The researchers sent pulses of light down a 100-m fiber-optic cable and measured their distortion and the changes in their profile—what the pulses looked like at different cross sections of the fiber. The researchers were then able to create new pulses of light with the initial profile that would counter the distortion of the cable. As a result, the scattering gets nullified and the pulse reaches the end of the cable intact. The technique could be useful for improving WiFi signals, medical imaging devices, laser transmissions, and more, but adapting it to a variety of media will be challenging.