Phys.org November 29, 2021
An international team of researchers (China, Spain) constructed a topological gallery insulator using sonic crystals made of thermoplastic rods that are decorated with carbon nanotube films, which act as a sonic gain medium by virtue of electro-thermoacoustic coupling. By engineering specific non-Hermiticity textures to the activated rods, they were able to break the chiral symmetry of the whispering-gallery modes, which enables the out-coupling of topological ‘audio lasing’ modes with the desired handedness. Adding gain makes it possible to amplify to break the chiral symmetry. The laboratory tests have demonstrated that when these elements are applied, the resulting sound resembles to the sound of a high-intensity laser beam. The work could have application in medical and industrial imaging and non-destructive testing and acoustic sensing…read more. TECHNICAL ARTICLEÂ
Complex band diagram of a sonic topological insulator with acoustic gain. Credit: Nature volume 597, pages655–659 (2021)Â