of the emitter. 3 Simultaneously, a
team of researchers from the University of Michigan presented an electrically driven polariton laser device
based on a comparable structure in
Physical Review Letters. 4 Both independently developed devices encourage
the realization of future electrically
driven room-temperature polariton
lasers because polariton condensates
at such temperatures have been
achieved under optical pumping in
appropriate material systems. 5
In stark contrast to conventional semi- conductor laser operation which relies
on stimulated emission of photons,
a polariton laser relies on stimulated
scattering of bosons into a common
particle energy state. 1 In quantum-well
microcavities, exciton-polaritons arise
in the strong light-matter-coupling
regime. These bosonic quasiparticles
can accumulate in a single energy state,
an effect closely related to Bose-Einstein
condensation of atoms. This macroscopically occupied quantum state—the
polariton condensate—provides coherent emission of light. This is in contrast
to a photon laser which can only be
operated in thermal non-equilibrium
(and hence requires strong pumping).
Polariton laser emission in thermal equilibrium with the host lattice is possible
and promises a more energy-efficient
In recent years, exciton-polariton
condensation studies attracted many
researchers worldwide. While an
early demonstration of polaritonic
lasing was achieved more than one
decade ago in optically pumped
semiconductor microcavities, electrical pumping of a polariton laser
was not demonstrated until 2013.2
This breakthrough in the practical
use of polaritonic light sources was
presented by our team of researchers together with our international
partners from the United States,
Japan, Russia, Singapore, Iceland
and Germany. 3
We recently reported in Nature an
unambiguous demonstration of an
electrically driven polariton laser,
where the strong-coupling regime
above the laser threshold is evidenced by magnetic-field interaction
A diagram of the electrically driven polariton laser. A high-quality GaAs microcavity
with four embedded quantum wells is employed to achieve stimulated scattering of polaritons (balls) from excited states (blue) into a macroscopically occupied ground-state
(red). A colored grid represents the respective energy-momentum dispersion of the
particles with the lowest energy state at the bottom.
A. Rahimi-Iman (arahimi-iman@
C. Schneider and S. Höfling
University of Würzburg, Germany
1. A. Imamoglu et al. Phys. Rev. A
53, 4250 (1996).
2. L.S. Dang et al. Phys. Rev. Lett.
81, 3920 (1998).
3. C. Schneider and A. Rahimi-Iman. Nature 497, 348 (2013).
4. P. Bhattacharya. Phys. Rev.
Lett. 110, 206403 (2013).
5. S. Christopoulos. Phys. Rev.
Lett. 98, 126405 (2007).
Electrically Driven Polariton Lasing