3-µm Nanosecond Pulsed Fiber Laser Enabled by the Porous Coordination Network Yellow Material

We report a passively Q-switched erbium-doped fiber laser operating at ~
$3~\mu \text{m}$
based on the porous coordination network yellow material (PCN-128Y), which was synthesized by the hydrothermal method. The modulation depth, non-saturable loss and saturable intensity of the PCN-128Y at
$\vphantom {_{\int }}~2.87~\mu \text{m}$
were measured to be 17.74%, 40.31%, and 0.0051 GW/cm2, respectively. By incorporating the PCN-128Y into an Er
$^{\mathrm {3+-}}$
doped ZBLAN fiber laser, stable Q-switched laser with a wavelength of 2785.2 nm was obtained. The maximum average output power of 350.1 mW at the repetition rate of 162.35 kHz was realized when the launched pump power was 2.07 W. The corresponding pulse energy and pulse width were
$2.16~\mu \text{J}$
and 604 ns, respectively, and the slope efficiency was 13.08%. This is the first time to demonstrate that the PCN-128Y can serve as a saturable absorber for the generation of 3-
$\mu \text{m}$
mid-infrared laser pulses, to the best of our knowledge. These results reveal the nonlinear absorption property of the PCN-128Y and will open the door for use of PCN-128Y in the 3-
$\mu \text{m}$
mid-infrared band.