Yellow lasers ( ∼ 565 – 590    nm ) are of tremendous interest in biomedicine, astronomy, spectroscopy, and display technology. So far, yellow lasers still have relied heavily on nonlinear frequency conversion of near-infrared lasers, precluding compact and low-cost yellow laser systems. Here, we address the challenge through demonstrating, for the first time, to the best of our knowledge, watt-level high-power yellow laser generation directly from a compact fiber laser. The yellow fiber laser simply consists of a Dy 3 + -doped ZBLAN fiber as gain medium, a fiber end-facet mirror with high reflectivity at yellow and a 450-nm diode laser as the pump source. We comprehensively investigated the dependence of the yellow laser performance on the output coupler reflectivity and the gain fiber length and demonstrated that the yellow fiber laser with an output coupler reflectivity of 4% and a gain fiber length of ∼ 1.8    m yields a maximum efficiency of 33.6%. A maximum output power of 1.12 W at 575 nm was achieved at a pump power of 4.20 W. This work demonstrated the power scaling of yellow Dy 3 + -doped ZBLAN fiber lasers, showing their promise for applications in ophthalmology, astronomical exploration, and high-resolution spectroscopy.

Mode-locked fibre lasers (MLFLs) are fundamental building blocks of many photonic systems used in industrial, scientific and biomedical applications. To date, 1-2 μm MLFLs have been well developed; however, passively modelocked fibre lasers in the visible region (380-760 nm) have never been reported. Here, we address this challenge by demonstrating an all-fibre visible-wavelength passively mode-locked picosecond laser at 635 nm. The 635 nm mode-locked laser with an all-fibre figure-eight cavity uses a Pr/Yb codoped ZBLAN fibre as the visible gain medium and a nonlinear amplifying loop mirror as the mode-locking element. First, we theoretically predict and analyse the formation and evolution of 635 nm mode-locked pulses in the dissipative soliton resonance (DSR) regime by solving the Ginzburg-Landau equation. Then, we experimentally demonstrate the stable generation of 635 nm DSR mode-locked pulses with a pulse duration as short as~96 ps, a radio-frequency signal-to-noise ratio of 67 dB and a narrow spectral bandwidth of <0.1 nm. The experimental results are in excellent agreement with our numerical simulations. In addition, we also observe 635 nm noise-like pulse operation with a wide (>1 nm) and modulated optical spectrum. This work represents an important step towards miniaturized ultrafast fibre lasers in the visible spectral region.

Abstract The recent renaissance in pulsed lasers operating in the visible spectral region has been driven by their significant applications in a wide range of fields such as display technology, medicine, microscopy, material processing, and scientific research. Low-dimensional nanomaterials as saturable absorbers are exploited to create strong nonlinear saturable absorption for pulse generation at visible wavelengths due to their absorption peaks located in visible spectral region. Here we provide a detailed overview of visible-wavelength pulsed lasers based on low-dimensional nanomaterials, covering the optical properties and various integration strategies of these nanomaterials saturable absorbers, and their performance from solid-state as well as fiber pulsed lasers in the visible spectral range. This emerging application domain will undoubtedly lead to the rapid development of visible pulsed lasers.

We demonstrate visible-wavelength all-fiber pulsed vortex lasers for the first time that may serve as attractive alternatives to solid-state vortex lasers for a variety of applications, such as visible mode-division multiplexing and STED microscopy.

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