  Exciton-polaritons are mixed light-matter particles offering a versatile
solid state platform to study many-body physical effects. In this work we
demonstrate an electrically controlled polariton laser, in a compact,
easy-to-fabricate and integrable configuration, based on a semiconductor
waveguide. Interestingly, we show that polariton lasing can be achieved in a
system without a global minimum in the polariton energy-momentum dispersion.
The surface cavity modes for the laser emission are obtained by adding couples
of specifically designed diffraction gratings on top of the planar waveguide,
forming an in-plane Fabry-Perot cavity. It is thanks to the waveguide geometry,
that we can apply a transverse electric field in order to finely tune the laser
energy and quality factor of the cavity modes. Remarkably, we exploit the
system sensitivity to the applied electric field to achieve an electrically
controlled population of coherent polaritons. The precise control that can be
reached with the manipulation of the grating properties and of the electric
field provides strong advantages to this device in terms of miniaturization and
integrability, two main features for the future development of coherent sources
from polaritonic technologies.
