The developed spatiotemporal mode‐locked (STML) laser has emerged as an effective platform for investigating high‐dimensional nonlinear spatiotemporal dynamics. Additionally, it offers a novel avenue for the design of fiber oscillators capable of operating at high power levels. At present, the focus of STML laser research primarily revolves around this aspect. However, considering practical applications, there is a strong desire to conceive a simple all‐fiber STML oscillator with both high beam quality and high power. In this study, an all‐fiber, high‐power STML oscillator based on multimode fibers is constructed and investigated. By manipulating the pump power and the polarization state, the laser could operate in a dissipative soliton or noise‐like pulse regime, both with average output powers of two operation states reaching the Watt level. Simultaneously, high‐quality output beam profiles are observed in both operation states. To the best of knowledge, this is the first demonstration of high‐power spatiotemporal mode‐locking with high beam quality. The study holds great benefits for advancing the investigations of compact all‐fiber STML lasers which deliver high‐power outputs with superior beam quality and ultimately propels the application of STML lasers. Furthermore, this study contributes to the understanding of the behavior of STML lasers with high power.

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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.

We systematically studied several of the most traditional hollow-core anti-resonant fiber (HC-ARF) structures, with the aim of achieving low confinement loss, single-mode performance, and high insensitivity to bending in the 2 µm band. Moreover, the propagation loss of fundamental mode (FM), higher-order mode (HOMs), and the higher-order mode extinction ratio (HOMER) under different geometric parameters were studied. Analysis showed that the confinement loss of the six-tube nodeless hollow-core anti-resonant fiber at 2 µm was 0.042 dB/km, and its higher-order mode extinction ratio was higher than 9000. At the same time, a confinement loss of 0.040 dB/km at 2 was is achieved in the five-tube nodeless hollow-core anti-resonant fiber, and its higher-order mode extinction ratio was higher than 2700.

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