16 research outputs found
Stability of Spatial Optical Solitons
We present a brief overview of the basic concepts of the soliton stability
theory and discuss some characteristic examples of the instability-induced
soliton dynamics, in application to spatial optical solitons described by the
NLS-type nonlinear models and their generalizations. In particular, we
demonstrate that the soliton internal modes are responsible for the appearance
of the soliton instability, and outline an analytical approach based on a
multi-scale asymptotic technique that allows to analyze the soliton dynamics
near the marginal stability point. We also discuss some results of the rigorous
linear stability analysis of fundamental solitary waves and nonlinear impurity
modes. Finally, we demonstrate that multi-hump vector solitary waves may become
stable in some nonlinear models, and discuss the examples of stable
(1+1)-dimensional composite solitons and (2+1)-dimensional dipole-mode solitons
in a model of two incoherently interacting optical beams.Comment: 34 pages, 9 figures; to be published in: "Spatial Optical Solitons",
Eds. W. Torruellas and S. Trillo (Springer, New York
Real-space collapse of a polariton condensate
Microcavity polaritons are two-dimensional bosonic fluids with strong nonlinearities,
composed of coupled photonic and electronic excitations. In their condensed form, they
display quantum hydrodynamic features similar to atomic BoseâEinstein condensates, such as
long-range coherence, superfluidity and quantized vorticity. Here we report the unique
phenomenology that is observed when a pulse of light impacts the polariton vacuum: the fluid
which is suddenly created does not splash but instead coheres into a very bright spot. The
real-space collapse into a sharp peak is at odd with the repulsive interactions of polaritons
and their positive mass, suggesting that an unconventional mechanism is at play. Our
modelling devises a possible explanation in the self-trapping due to a local heating of the
crystal lattice, that can be described as a collective polaron formed by a polariton condensate.
These observations hint at the polariton fluid dynamics in conditions of extreme intensities
and ultrafast times
Ultrathin Ga2O3 Glass: A Large-Scale Passivation and Protection Material for Monolayer WS2
Atomically thin transition metal dichalcogenide crystals (TMDCs) have extraordinary optical properties that make them attractive for future optoelectronic applications. Integration of TMDCs into practical all-dielectric heterostructures hinges on the ability to passivate and protect them against necessary fabrication steps on large scales. Despite its limited scalability, encapsulation of TMDCs in hexagonal boron nitride (hBN) currently has no viable alternative for achieving high performance of the final device. Here, it is shown that the novel, ultrathin Ga2 O3 glass is an ideal centimeter-scale coating material that enhances optical performance of the monolayers and protects them against further material deposition. In particular, Ga2 O3 capping of monolayer WS2 outperforms commercial-grade hBN in both scalability and optical performance at room temperature. These properties make Ga2 O3 highly suitable for large-scale passivation and protection of monolayer TMDCs in functional heterostructures