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In this work, we propose, to the best of our knowledge, the first demonstration of a ~3.5 μm dual-wavelength pumping (DWP) Er3+-doped ZBLAN fiber laser gain switched by 976 nm pulses. The DWP scheme is composed of a pulsed 976 nm laser system and a home-made continuous-wave 1973 nm laser. Stable pulses were obtained with repetition rates ranging between 5.2 kHz and 10 kHz. The maximum output power energy of 50.4 μJ was achieved at 10 kHz with a wavelength of 3445.9 nm. The temporal profile of the pulse trains was characterized by stable relaxation spike pulses containing a series of sub-pulses. The pulse characteristics with respect to the pump energy and the underlying mechanism are discussed. This work makes an effort to better understand the dynamics and theory of the cascade pumping system, and provides a new perspective for the realization of high-power pulses beyond 3 μm.

We report a dual-wavelength tunable passively Q-switched Er3+ -doped ZBLAN fiber laser at ~3 nm using a bulk PtSe2 as a saturation absorber. Stable pulses were generated for average output power of 504.0 mW at 72.9 kHz repetition rate. The corresponding pulse width and pulse energy were measured to be 1.26 μs and 6.92 μJ, respectively. By tuning the feedback angle of the plane ruled grating, the spectra show simultaneous dual-wavelength pulsed operations with tuning range of 51.5 nm (2745.5-2797.0 nm) at the launched pump of 2.27 W.

We report Q-switched Er3+ -doped ZBLAN fiber lasers operating at 2.8 μm based on MIL-68(Al) (MIL: Materials of Institute Lavoisier), for the first time. The nonlinear absorption of MIL-68(Al) was characterized by using a homemade nonlinear absorption measurement system. The modulation depth, non-saturable loss, and saturation peak intensity are determined to be 24.43 %, 58.63%, and 0.0335 GW/cm2, respectively. A piece of 6 mol.% multimode Er3+ -doped ZBLAN fiber was used as the gain medium. The maximum average output power as high as 1.18 W was reached with the shortest pulse duration as short as 546 ns at a repetition rate of 106.71 kHz. The corresponding pulse energy and peak power were 11.03 μJ and 20.19 W, respectively. Then, we replaced the gain fiber with a 7 mol.% single-mode Er3+ -doped ZBLAN fiber and achieved nanosecond pulses with a pulse duration of 846 ns and average output power of 0.734 W. The corresponding pulse energy and peak power were 3.68 μJ and 4.25 W, respectively. Our work shows that the MIL-68(Al) is a promising stable SA for mid-infrared high-power nanosecond laser pulses generation.