Fig. 1 (IMAGE) Science China Press Caption (left) a conventional waveguide-resonator v.s. (right) a topological insulator waveguide-resonator. Upstream reflection is fundamentally suppressed in the latter one, even in the case of critical coupling. Credit @Science China Press Usage Restrictions Use with credits License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.