Ultrashort pulse generation at the short-wave infrared (SWIR) wavelength ranges from 1.6 to 2.5μm and together with benefits of the all-fiber design has transformed lasers into an essential tool for industrial, technological, scientific, environmental, and medical applications. With the development of pumping sources and fiber components, ultrafast SWIR fiber lasers have drawn exceptional research and industrial attention over the last decade, resulting in the achievement of comparable performance or even surpassing well-established near-IR sources. Exceptionally compact, highly stable, cost-effective, and maintenance-free ultrafast fiber lasers operating at the SWIR range are currently well on the way to be commercially employed. This invited Perspective article gives a comprehensive overview of the most significant achievements enabling ultrafast generation at SWIR, including up-to-date gain fibers and saturable absorbers, nonlinear process, and laser architectures. This article highlights the perspectives and strategies for further maturing of the field of SWIR fiber lasers and pathways for the improvement of the performance, overcoming existing bottlenecks and challenges toward reducing pulse durations, tunability of repetition rate, and power upscaling. The advancement of the ultrafast SWIR laser development is projected until the landscape of existing technologies, driven by these ultimate sources, and potential applications, emerging on the horizon.

Ensuring self-driven mode-locking and broadband wavelength tuneability in all-fibre-integrated femtosecond laser sources enables a new level of their versatility and extends areas of their applications. Principle limitations for this are traditionally available ultrafast modulators and tuneability techniques. Here, we exploit Thulium-doped fibre to perform three roles in the cavity: laser gain, saturable absorber, and tuneability element via controlling its excitation level. We confirmed that Tm-doped fibre saturable absorption is defined by a reinforced quenching of Tm3+ pairs. As a result, we present both numerically and experimentally a highly stable sub-picosecond pulse generation with a ~90 nm tuneability range spanning from 1873 to 1962 nm via adjusting the cavity feedback. The maximum laser efficiency corresponds to 25% cavity feedback, enabling the highest output energy of 1 nJ in 600-fs solitons at 1877 nm. Overall, the presented laser system establishes a compact and straightforward approach for ultrafast generation, which can be translated to other fibre laser operation wavelengths.

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Implication of self-mode-locking originated from lion-excited Thulium ions is investigated to construct a cost-effective 1.9 pm all-fibre laser. The laser generates 350fs solitons with 1.1811J energy at 44.8MHz repetition rate in flawless mode-locking.)

The impact of thulium ions clustering on saturable absorption of active fibres is investigated. The self-mode-locked thulium-doped laser demonstrates 350-fs solitons at 45-MHz repetition rate with 80-mW average power, making this an affordable, durable, and all-fibre integrated instrumentation.