Mid-infrared (MIR) ultrashort laser pulses have a wide range of applications in the fields of environmental monitoring, laser medicine, food quality control, strong-field physics, attosecond science, and some other aspects. Recent years have seen great developments in MIR laser technologies. Traditional solid-state and fiber lasers focus on the research of the short-wavelength MIR region. However, due to the limitation of the gain medium, they still cannot cover the long-wavelength region from 8 to 20 µm. This paper summarizes the developments of 8–20 μm MIR ultrafast laser generation via difference frequency generation (DFG) and reviews related theoretical models. Finally, the feasibility of MIR power scaling by nonlinear-amplification DFG and methods for measuring the power of DFG-based MIR are analyzed from the author’s perspective.

Two-dimensional material nanosheets have always been a research hotspot because of their unique structure and properties. We report mode-locked operation in ytterbium-doped fiber laser (YDFL) for the first time by adopting Fe₃O₄ nanosheets as a saturable absorber (SA). The laser is capable of generating 456 ps pulses, centered around 1039 nm. Our results manifest that Fe₃O₄ nanosheets are expected to become a new type of saturable absorber, which can better promote the development of mode-locked lasers.

In this paper, we report for the first time on an all-multimode fiber spatiotemporal mode-locked figure-eight laser operating at 1.0 µm. This laser utilizes a multimode gain fiber and a nonlinear amplifying loop mirror mechanism. It can generate mode-locked noise-like pulses at different central wavelengths. Additionally, we observed the presence of a multi-soliton state within the cavity by reducing intracavity gain. This study contributes to a broader investigation of various pulse phenomena in spatiotemporal mode-locked lasers and provides valuable insights into further exploring the evolution of spatiotemporal dynamics in such systems.

A self-made saturable absorber (SA) based on hybridized graphene oxide (GO) and F e 3 O 4 nanoparticles (FONP) was inserted into a linear cavity to generate a passively Q -switched solid-state N d : Y V O 4 laser operating at the 1.3 µm waveband. The laser had a minimum pulse width of 163 ns and a maximum repetition rate of 314 kHz. This experiment, to the best of our knowledge, is the first to demonstrate that hybridized GO and FONP (GO-FONP) can be used as an SA in passively Q -switched pulse lasers. Results show that GO-FONP has the potential to be used for passively Q -switched laser generation.

In this paper, a diode-pumped CW Kerr lens mode-locked Nd:YVO₄ laser is demonstrated in the megahertz (MHz) oscillations mode-locked regime for the first time. Considered the beam mode size in the laser crystal and the Kerr lens sensitivity, an effective laser system with a symmetrical z-shaped cavity is strictly designed by the ABCD matrix and experimentally researched. The laser system can be self-starting without the need of any additional components. When an incident pump power is of 8 W, the maximum output power is 1.65 W, with a slope efficiency of 23.8%. The mode-locked repetition rate and pulse width are 530 MHz and 15.1 ps, respectively.