16 March 2018
Vol 359, Issue 6381

About The Cover

Cover image expansion

COVER Illustration of a nonmagnetic topological insulator laser: an array of microring resonators (circles) coupled by waveguides (ellipses) in a topological fashion. The red perimeter depicts the lasing topological edge mode, which exits through one of the two outputs (solid red triangle). Implementation of this design in an all-dielectric semiconductor enhances lasing performance and makes many diode lasers operate together as a single highly coherent laser. See pages 1230 and 1231.
Illustration: Valerie Altounian/Science