Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical Rotation Quasi-Phase-Matching for Circularly Polarized High
  Harmonic Generation   The first scheme for quasi-phase-matching high harmonic generation of
circularly polarized radiation is proposed: optical rotation
quasi-phase-matching (ORQPM). In ORQPM propagation of the driving radiation in
a system exhibiting circular birefringence causes its plane of polarization to
rotate; by appropriately matching the period of rotation to the coherence
length it is possible to avoid destructive interference of the generated
radiation. It is shown that ORQPM is approximately 5 times more efficient than
conventional QPM, and half as efficient as true phase-matching.

28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn