The researchers were able to control light by using random crystal lattice structures to counteract light diffraction. Technology that prevents diffraction and controls light more precisely, says the team, could lead to advances in optical communications.
To control light on the nanoscale, the researchers used a photonic crystal superlattice – a disorderly pattern with thousands of nanoscale heptagonal, square and triangular holes.
While it has been known that uniformly patterned holes can control the spatial diffraction to some extent, the researchers found that structures with the most disorderly patterns were best able to trap and collimate the beam and that the structure worked over a broad part of the infrared spectrum.
The effect, known as Anderson localisation, was first proposed in 1958 by Nobel laureate Philip Anderson. The new study is the first to examine transverse Anderson localisation in a chip scale photonic crystal media.
Researcher Pin-Chun Hsieh said the findings are completely counterintuitive because one might think that disorder would lead the light to spread out more. "This effect, based on intuition gained from electronic systems, where introduced impurities can turn an insulator into a semiconductor, shows unequivocally that controlling disorder can arrest transverse transport, and really reduce the spreading of light."
