Long-term stable platinum diselenide for nanosecond pulse generation in a 3-µm mid-infrared fiber laser

In this paper, we fabricate the bulk-like multilayer platinum diselenide (PtSe 2 ) and employ it as saturable absorber (SA) for a passively Q-switched fiber laser operating at 2865 nm for the first time, to the best of our knowledge. The nonlinear optical measurements of the bulk-like multilayer PtSe 2 reveal efficient saturable absorption property at around 3 µm showing a modulation depth of 8.54% and a saturation intensity of 0.074 GW/cm 2 . By introducing the bulk-like PtSe 2 -SA into the Ho 3+ /Pr 3+ co-doped ZBLAN fiber laser, stable Q-switched pulses with a duration as short as 620 ns are achieved at the pulse repetition rate of 238.1 kHz. The maximum average power is 93 mW, corresponding to a peak power of 0.63 W. The excellent long-term stability of the PtSe 2 -SA was also verified utilizing the same experimental setup after 40 days of ambient storage of the PtSe 2 sample. The results not only validate the excellent nonlinear optical performance of PtSe 2 , but also indicate that the bulk-like PtSe 2 is a promising long-term stable SA material under ambient conditions for nanosecond pulse generation in the 3-µm mid-infrared spectral region.