Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cavity-enhanced narrow bandwidth photon pairs generation at the telecom
  wavelength with a triple resonance configuration   In this paper, we present a narrow bandwidth source at the telecom wavelength
based on type II PPKTP crystal inside an optical cavity. Simultaneous
resonances of the pump and the two down-converted fields are achieved by
special design of the cavity. This is a triple resonances optical parametric
oscillator (OPO) far below threshold, which generates photon pairs at around
1560 nm with a bandwidth of 8 MHz. A coherence time of 27.7 ns is estimate by a
time correlation measurement, and the estimated photon pairs generating rate is
134 s-1MHz-1mW-1. As entangled photon pairs in the telecom regime is suitable
for long distance transmission and manipulation, this source is desirable for
the demands of quantum communication.

10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin