Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasinormal mode analysis of chiral power flow from linearly polarized
  dipole emitters coupled to index-modulated microring resonators close to an
  exceptional point   Chiral emission can be achieved from a circularly polarized dipole emitter in
a nanophotonic structure that possess special polarization properties such as a
polarization singularity, namely with right or left circularly polarization
(C-points). Recently, Chen et al. [Nature Physics 16, 571 (2020)] demonstrated
the surprising result of chiral radiation from a linearly-polarized (LP) dipole
emitter, and argued that this effect is caused by a decoupling with the
underlying eigenmodes of a non-Hermitian system, working at an exceptional
point (EP). Here we present a quasinormal mode (QNM) approach to model a
similar index-modulated ring resonator working near an EP and show the same
unusual chiral power flow properties from LP emitters, in direct agreement with
the experimental results. We explain these results quantitatively without
invoking the interpretation of a missing dimension (the Jordan vector) and a
decoupling from the cavity eigenmodes, since the correct eigenmodes are the
QNMs which explain the chiral emission using only two cavity modes. By coupling
a LP emitter with the dominant two QNMs of the ring resonator, we show how the
chiral emission depend on the position and orientation of the emitter, which is
also verified by the excellent agreement with respect to the power flow between
the QNM theory and full numerical dipole solutions. We also show how a normal
mode solution will fail to capture the correct chirality since it does not take
into account the essential QNM phase. Moreover, we demonstrate how one can
achieve frequency-dependent chiral emission, and replace lossy materials with
gain materials in the index modulation to reverse the chirality.

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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int