Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Large few-layer hexagonal boron nitride flakes for nonlinear optics   Hexagonal boron nitride (hBN) is a layered dielectric material with a wide
range of applications in optics and photonics. In this work, we demonstrate a
fabrication method for few-layer hBN flakes with areas up to 5000 $\rm \mu m$.
We show that hBN in this form can be integrated with photonic microstructures:
as an example, we use a circular Bragg grating (CBG). The layer quality of the
exfoliated hBN flake on a CBG is confirmed by second-harmonic generation (SHG)
microscopy. We show that the SHG signal is uniform across the hBN sample
outside the CBG and is amplified in the centre of the CBG.

1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int