Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A circular dielectric grating for vertical extraction of single quantum
  dot emission   We demonstrate a nanostructure composed of partially etched annular trenches
in a suspended GaAs membrane, designed for efficient and moderately broadband
(approx. 5 nm) emission extraction from single InAs quantum dots. Simulations
indicate that a dipole embedded in the nanostructure center radiates upwards
into free space with a nearly Gaussian far-field, allowing a collection
efficiency > 80 % with a high numerical aperture (NA=0.7) optic, and with 12X
Purcell radiative rate enhancement. Fabricated devices exhibit an approx. 10 %
photon collection efficiency with a NA=0.42 objective, a 20X improvement over
quantum dots in unpatterned GaAs. A fourfold exciton lifetime reduction
indicates moderate Purcell enhancement.

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The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs