Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Decoding Ultrafast Polarization Responses in Lead Halide Perovskites by
  the Two-Dimensional Optical Kerr Effect   The ultrafast polarization response to incident light and ensuing
exciton/carrier generation are essential to outstanding optoelectronic
properties of lead halide perovskites (LHPs). A large number of mechanistic
studies in the LHP field to date have focused on contributions to
polarizability from organic cations and the highly polarizable inorganic
lattice. For a comprehensive understanding of the ultrafast polarization
response, we must additionally account for the nearly instantaneous
hyperpolarizability response to the propagating light field itself. While light
propagation is pivotal to optoelectronics and photonics, little is known about
this in LHPs in the vicinity of the bandgap where stimulated emission,
polariton condensation, superfluorescence, and photon recycling may take place.
Here we develop two-dimensional optical Kerr effect (2D-OKE) spectroscopy to
energetically dissect broadband light propagation and dispersive nonlinear
polarization responses in LHPs. In contrast to earlier interpretations, the
below-bandgap OKE responses in both hybrid CH3NH3PbBr3 and all-inorganic
CsPbBr3 perovskites are found to originate from strong hyperpolarizability and
highly anisotropic dispersions. In both materials, the nonlinear mixing of
anisotropically propagating light fields result in convoluted oscillatory
polarization dynamics. Based on a four-wave mixing model, we quantitatively
derive dispersion anisotropies, reproduce 2D-OKE frequency correlations, and
establish polarization dressed light propagation in single crystal LHPs.
Moreover, our findings highlight the importance of distinguishing the
often-neglected anisotropic light propagation from underlying coherent
quasi-particle responses in various forms of ultrafast spectroscopy.

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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: solv-int