Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Slow light with fractional optical angular momentum in a photonic
  crystal ring   Whispering gallery modes (WGMs) in circularly symmetric optical
microresonators exhibit integer quantized angular momentum numbers due to the
boundary condition imposed by the geometry. Here, we show that incorporating a
photonic crystal pattern in an integrated microring can result in WGMs with
fractional optical angular momentum. By choosing the photonic crystal
periodicity to open a photonic bandgap with a band-edge momentum lying between
that of two WGMs of the unperturbed ring, we observe hybridized WGMs with
half-integer quantized angular momentum numbers ($m \in \mathbb{Z}$ + 1/2).
Moreover, we show that these modes with fractional angular momenta exhibit high
optical quality factors with good cavity-waveguide coupling, an order of
magnitude reduced group velocity, and also can co-exist with more localized
states when a defect is introduced in the photonic crystal lattice. Our work
unveils WGMs with fractional angular momentum, which can be used in
sensing/metrology, nonlinear optics, and cavity quantum electrodynamics.

8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin