  With a seminal work of Raghu and Haldane in 2008, concepts of topology have
been successfully introduced in a wide range of optical systems, emulating
specific lattice Hamiltonians. Certainly, one of the most promising routes to
an application of topological photonics in an actual device are topological
lasers, where efficient and highly coherent lasing from a topologically
non-trivial mode is achieved. While some attempts have been made to excite such
structures electrically, the majority of published fundamental experiments use
a form of laser excitation. In this paper, we use a lattice of vertical
resonator polariton micropillars to form an exponentially localized topological
Su-Schrieffer-Heeger defect. Upon electrical excitation of the p-i-n doped
structure, the system unequivocally shows polariton lasing from the topological
defect using a carefully placed gold contact. Despite the presence of doping
and electrical contacts, the polariton band structure clearly preserves its
topological properties. At high excitation power the Mott density is exceeded
leading to highly efficient lasing in the weak coupling regime. This work is an
important step towards applied topological lasers using vertical resonator
microcavity structures.
