  Topological insulator lasers (TILs) are a recently introduced family of
lasing arrays in which phase locking is achieved through synthetic gauge
fields. These single frequency light source arrays operate in the spatially
extended edge modes of topologically non-trivial optical lattices. Because of
the inherent robustness of topological modes against perturbations and defects,
such topological insulator lasers tend to demonstrate higher slope efficiencies
as compared to their topologically trivial counterparts. So far, magnetic and
non-magnetic optically pumped topological laser arrays as well as electrically
pumped TILs that are operating at cryogenic temperatures have been
demonstrated. Here we present the first room temperature and electrically
pumped topological insulator laser. This laser array, using a structure that
mimics the quantum spin Hall effect for photons, generates light at telecom
wavelengths and exhibits single frequency emission. Our work is expected to
lead to further developments in laser science and technology, while opening up
new possibilities in topological photonics.
