We report on the generation of large pulse duration-tuning and wide wavelength-tunable mode-locked pulses, operating in a dissipative soliton resonance (DSR) region, by an all-normal-dispersion Yb-doped figure-eight fibre laser. For the case of a DSR operating at 1045.1 nm, the pulse duration varies from 26.3 ps to 8.621 ns with the increase of pump power. At the maximum pump power of 400 mW, the pulse energy is as high as 4.8 nJ. In particular, through properly adjusting the polarization controllers, the DSR can be wavelength-tuned in a wide range from 1037.3 to 1075.3 nm. To the best of our knowledge, this is the widest tunable range ever reported for DSR operation. This wavelength-tunable mode-locked fibre laser with a high-energy output may be well-suited for many potential applications.

Pork accounts for an important proportion of livestock products. For pig farming, a lot of manpower, material resources and time are required to monitor pig health and welfare. As the number of pigs in farming increases, the continued use of traditional monitoring methods may cause stress and harm to pigs and farmers and affect pig health and welfare as well as farming economic output. In addition, the application of artificial intelligence has become a core part of smart pig farming. The precision pig farming system uses sensors such as cameras and radio frequency identification to monitor biometric information such as pig sound and pig behavior in real-time and convert them into key indicators of pig health and welfare. By analyzing the key indicators, problems in pig health and welfare can be detected early, and timely intervention and treatment can be provided, which helps to improve the production and economic efficiency of pig farming. This paper studies more than 150 papers on precision pig farming and summarizes and evaluates the application of artificial intelligence technologies to pig detection, tracking, behavior recognition and sound recognition. Finally, we summarize and discuss the opportunities and challenges of precision pig farming.

A continuous-wave erbium-doped ytterbium-free fiber laser generates a record-breaking pump-power-limited output power of 656 W at ∼1601  nm when cladding pumped by 0.98 μm diode lasers. The slope efficiency was 35.6% with respect to launched pump power, and the beam quality factor (M) was ∼10.5. This M value excludes a fraction ∼25% of the power that emerged from the cladding, which we attribute in part to mode coupling between the 146 μm core and 700 μm inner cladding. Whereas these parameters are adequate for in-band tandem pumping of Tm-doped fiber lasers, we predict that an output power of over 1 kW is possible through pumping with state-of-the-art 0.98 μm diode lasers, even with a smaller core that allows for improved beam quality.

High-energy square pulses operating in dissipative soliton resonance region are experimentally observed in an erbium-doped figure-of-eight fiber laser with large net-normal dispersion for the first time to our knowledge. The dissipative soliton resonance is achieved by using the nonlinear-amplifying-loop-mirror mode-locked technique. The output pulse duration broadens linearly with the increase of pump power, while the peak power maintains a constant value. At the maximum pump power of 620 mW, the intracavity pulse energy is up to 379.2 nJ, and the average output power is 14.02 mW.

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