Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber
  laser at 2.8 {\mu}m   Black phosphorus, a newly emerged two-dimensional material, has attracted
wide attention as novel photonic material. Here, multi-layer black phosphorus
is successfully fabricated by liquid phase exfoliation method. By employing
black phosphorus as saturable absorber, we demonstrate a passively Q-switched
Er-doped ZBLAN fiber laser at the wavelength of 2.8 {\mu}m. The modulation
depth and saturation fluence of the black phosphorus saturable absorber are
measured to be 15% and 9 {\mu}J/cm2, respectively. The Q-switched fiber laser
delivers a maximum average power of 485 mW with corresponding pulse energy of
7.7 {\mu}J and pulse width of 1.18 {\mu}s at repetition rate of 63 kHz. To the
best of our knowledge, this is the first time to demonstrate that black
phosphorus can realize Q-switching of 2.8-{\mu}m fiber laser. Our research
results show that black phosphorus is a promising saturable absorber for
mid-infrared pulsed lasers.

37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin