Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Selective Pumping of Localized States in a Disordered Active Medium   Light scattering and localization in strongly scattering disordered systems
is governed by the nature of the underlying eigenmodes, specially their spatial
extension within the system. One of the main challenges in studying
experimentally Anderson like localized states resides in the difficulty to
excite these states independently and observe them individually anywhere in the
sample. The modes mutual interaction and their coupling to the sample
boundaries makes it extremely challenging to isolate them spectrally and image
them alone. In the presence of gain, random lasing occurs above threshold and
lasing modes are excited. It was shown recently that shaping the intensity
profile of the optical pump is a very effective way to control and force random
lasing in singlemode regime at any desired emission wavelength. Active random
media therefore offer a unique platform to select modes individually. By using
pump shaping technique in a strongly scattering random laser, we successfully
select localized lasing modes individually. Direct imaging of the light
distribution within the random laser confirms the confined nature of the modes
and enables us to elucidate long standing questions on the role of
non-Hermiticity in active scattering media and the influence of nonlinearities
on Anderson wave localization.

23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc