Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photonic Generation of High Power, Ultrastable Microwave Signals by
  Vernier Effect in a Femtosecond Laser Frequency Comb   Optical frequency division of an ultrastable laser to the microwave frequency
range by an optical frequency comb has allowed the generation of microwave
signals with unprecedently high spectral purity and stability. However, the
generated microwave signal will suffer from a very low power level if no
external optical frequency comb repetition rate multiplication device is used.
This paper reports theoretical and experimental studies on the beneficial use
of the Vernier effect together with the spectral selective filtering in a
double directional coupler add-drop optical fibre ring resonator to increase
the comb repetition rate and generate high power microwaves. The studies are
focused on two selective filtering aspects: the high rejection of undesirable
optical modes of the frequency comb and the transmission of the desirable modes
with the lowest possible loss. Moreover, the conservation of the frequency comb
stability and linewidth at the resonator output is particularly considered.
Accordingly, a fibre ring resonator is designed, fabricated, and characterized,
and a technique to stabilize the resonator's resonance comb is proposed. A
significant power gain is achieved for the photonically generated beat note at
10 GHz. Routes to highly improve the performances of such proof-of-concept
device are also discussed.

6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an