Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dual-wavelength vortex beam with high stability in diode-pumped
  Yb:CaGdAlO4 Laser   We present a stable dual-wavelength vortex beam carrying orbital angular
momentum (OAM) with two spectral peaks separated by a few terahertz in
diode-pumped Yb:CaGdAlO4 (CALGO) laser. The dual-wavelength spectrum is
controlled by the pump power and off-axis loss in laser resonator, arising from
the broad emission bandwidth of Yb:CALGO. The OAM beam is obtained by a pair of
cylindrical lens that serves as an {\pi}/2 convertor for the high-order
Hermite-Gaussian modes. The stability is verifed that the 1 h OAM beam with two
spectral peaks at 1046.1 nm and 1057.2 nm (3.01 THz interval) can steadily
operate for more than three hours. It has great potential for scaling the
application for OAM beams in Terahertz spectroscopy, high-resolution
interferometry, and so on.

36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin