"Typically, symmetry connotes harmony and beauty. But not in this case. We've developed technology – an asymmetric metawaveguide – that enables a weak control laser beam to manipulate a much more intense laser signal," says Liang Feng, assistant professor at Buffalo University.
Light-light switching typically requires strong nonlinearity where intense laser fields route and direct data flows of weak power, leading to a high power consumption that limits its practical use.
In this study, the experimental demonstration of a metawaveguide – a tiny rectangular box made of silicon – operates in the opposite way in a linear regime, where an intense laser field is interferometrically manipulated on demand by a weak control beam with a modulation extinction ratio up to 60dB. This asymmetric control is said to result from operating near an exceptional point of the scattering matrix, which gives rise to intrinsic asymmetric reflections of the metawaveguide through interplay between index and absorption.