3 research outputs found
Electrically controlling vortices in a neutral exciton polariton condensate at room temperature
Manipulating bosonic condensates with electric fields is very challenging as
the electric fields do not directly interact with the neutral particles of the
condensate. Here we demonstrate a simple electric method to tune the vorticity
of exciton polariton condensates in a strong coupling liquid crystal (LC)
microcavity with CsPbBr microplates as active material at room temperature.
In such a microcavity, the LC molecular director can be electrically modulated
giving control over the polariton condensation in different modes. For
isotropic non-resonant optical pumping we demonstrate the spontaneous formation
of vortices with topological charges of +1, +2, -2, and -1. The topological
vortex charge is controlled by a voltage in the range of 1 to 10 V applied to
the microcavity sample. This control is achieved by the interplay of a built-in
potential gradient, the anisotropy of the optically active perovskite
microplates, and the electrically controllable LC molecular director in our
system with intentionally broken rotational symmetry. Besides the fundamental
interest in the achieved electric polariton vortex control at room temperature,
our work paves the way to micron-sized emitters with electric control over the
emitted light's phase profile and quantized orbital angular momentum for
information processing and integration into photonic circuits
Single-shot spatial instability and electric control of polariton condensates at room temperature
In planar microcavities, the transverse-electric and transverse-magnetic
(TE-TM) mode splitting of cavity photons arises due to their different
penetration into the Bragg mirrors and can result in optical spin-orbit
coupling (SOC). In this work, we find that in a liquid crystal (LC) microcavity
filled with perovskite microplates, the pronounced TE-TM splitting gives rise
to a strong SOC that leads to the spatial instability of microcavity polariton
condensates under single-shot excitation. Spatially varying hole burning and
mode competition occurs between polarization components leading to different
condensate profiles from shot to shot. The single-shot polariton condensates
become stable when the SOC vanishes as the TE and TM modes are spectrally well
separated from each other, which can be achieved by application of an electric
field to our LC microcavity with electrically tunable anisotropy. Our findings
are well reproduced and traced back to their physical origin by our detailed
numerical simulations. With the electrical manipulation our work reveals how
the shot-to-shot spatial instability of spatial polariton profiles can be
engineered in anisotropic microcavities at room temperature, which will benefit
the development of stable polariton-based optoeletronic and light-emitting
devices