A photonic device that emits light only in one direction has been created by researchers in China and the US. Chao Peng, Marin Soljačić and colleagues at Peking University, the Massachusetts Institute of Technology and the University of Pennsylvania created their device by carefully tailoring the shape of a set of etched silica bars – thereby using topology to modify a curious effect that was predicted 90 years ago. The light source could have multiple applications in optoelectronics.
A key challenge in creating optical circuits is that light will happily travel in both directions through optical devices – which causes unwanted effects. Current solutions such integrating a mirror to reflect light travelling in the wrong direction tend to be bulky, inefficient or difficult to fabricate. Now, researchers in China and the US have put a topological twist on an effect first proposed in 1929 and created a photonic crystal that emits light in only one direction.
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