In our work, passively mode-locked and Q-switched Er-doped fiber lasers (EDFLs) based on titanium disulfide (TiS2) as a saturable absorber (SA) were generated successfully. Stable mode-locked pulses centred at 1531.69 nm with the minimum pulse width of 2.36 ps were obtained. By reducing the length of the laser cavity and optimizing the cavity loss, Q-switched operation with a maximum pulse energy of 67.2 nJ and a minimum pulse duration of 2.34 µs was also obtained. Its repetition rate monotonically increased from 13.17 kHz to 48.45 kHz with about a 35 kHz tuning range. Our experiment results fully indicate that TiS2 exhibits excellent nonlinear absorption performance and significant potential in acting as ultra-fast photonics devices.

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This paper reports an all-solid-state yellow laser, which is based on two Nd：YAG rods connected in series and the intracavity sum frequency generation in a KTP crystal by use of a V-shaped folding configuration, and continuous-wave 589 nm light with the output power of 3 W is obtained. In order to improve the output power of the yellow light, two means are introduced. One means is optimizing the space overlapping of two fundamental beams by optimized designing of the oscillators, and the other is optimizing the intracavity power ratio of two fundamental beams by choosing proper pump powers of the two beams.

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The second near-infrared (NIR II) response photon up-conversion (UC) materials show great application prospects in the fields of biology and optical communication. However, it is still an enormous challenge to obtain efficient NIR II response materials. Herein, we developed a series of Er3+ doping ternary sulfides phosphors with highly efficient UC emissions under 1532 nm irradiation. Excitingly, β-NaYS2:Er3+ achieves a breakthrough visible UC efficiency as high as 6.13%, along with outstanding brightness, spectral stability of lights illumination and temperature. Such efficient UC dominates by excited state absorption process accompanied by the advantage of super long lifetimes of excited state levels of Er3+, instead of the well-recognized energy transfer UC between sensitizer and activator. NaYS2:Er3+ phosphors are further developed for high-performance underwater communication and a narrowband NIR photodetectors. Our findings breakthrough the traditional thinking of realizing efficient UC, and open up a novel frontier for developing NIR II response UC materials.