Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Slow propagation of 2 GHz acoustical waves in a suspended GaAs on
  insulator phononic waveguide   Optoelectronic oscillators have dominated the scene of microwave oscillators
in the last few years thanks to their great performances regarding frequency
stability and phase noise. However, miniaturization of such a device is an up
to date challenge. Recently, devices based on phonon-photon interaction gather
a lot of interest thanks to their extreme compactness and working frequency
directly in the GHz. In this frame, a still missing element to obtain long-term
frequency stability performances is an on-chip delay within the feedback loop.
Here, we experimentally show filtering and slow propagation of 2 GHz acoustic
waves on a Gallium Arsenide membrane heterogeneously integrated on silicon
wafer. By engineering the dispersion of an acoustical waveguide, we evidence a
group velocity below 1000 m/s for the mode able to propagate. Thus, an
integrated delay implementation is at reach for potential improvement of
opto-acoustic devices such as optomechanical oscillators or wireless
applications.

31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th