We report a watt-level visible-near-infrared (NIR) dual-wavelength Pr3+:LiYF4 (Pr:YLF) laser. This is the first report about the realization of visible-NIR dual-wavelength lasing in Pr:YLF crystal. The dual-wavelength lasers of 698 & 868 nm and 721 & 915 nm are directly realized without inserting any elements in the resonant cavity. The maximum output powers of the 698 & 868 nm and 721 & 915 nm dual-wavelength lasers are 1.31 W and 1.74 W, corresponding to slope efficiencies of 25.7% and 23.8%, and laser output power stabilities of 1.18% and 1.21%, respectively. The successful realization of the watt-level high-performance visible-NIR dual-wavelength laser can provide practical applications in medical diagnostics, treatment, and laser precision detection.

We reported an 868 nm Pr3+:LiYF4 (Pr:YLF) laser pumped by an InGaN blue laser diode (LD) for the first time. The maximum power of the laser was 641 mW and the beam quality M-x(2) and M-y(2) factors were -2.66 in the xdirection and -2.32 in the y-direction, respectively. The output power fluctuation was stable within +/- 2 %. The 868 nm laser was successfully realized in Pr:YLF crystal by designing and optimizing the laser resonant cavity and optical thin films. In addition, we theoretically simulated the nonlinear relationship between the laser output power and the absorbed pump power, and the theoretical simulation results were in agreement with the experimental data. The first realization of the 868 nm Pr:YLF laser further expands the near-infrared lasers.

We reported a high-power 915 nm Pr3+:LiYF4 (Pr:YLF) laser dual-ended pumped by laser diodes (LDs). The maximum output power of the laser was 3.39 W with a slope efficiency of 19.8 %. The fluctuation range of the laser wavelength was less than 0.58 nm. As far as we know, this is the highest power at 915 nm for LD-pumped Pr:YLF lasers to date. To eliminate the power saturation phenomenon and further improve the laser output power, we proposed a simple and effective method, i.e., laser energy levels cascade. Based on the experimental data, we calculated the populations of P-3(0) and (1)G(4) energy levels in Pr:YLF crystal during laser cascading and developed two different models to verify the feasibility of the laser cascade mechanism. Moreover, the laser cascade could be realized merely by designing the lens film without introducing other devices, which provided a simple and effective solution for developing high-performance lasers.

We report a high-performance wavelength-switchable near-infrared Pr3+:LiYF4 (Pr:YLF) laser by InGaN laser diode (LD) pumping. The 895, 922, and 924 nm lasers with low emission cross sections in the Pr:YLF crystal have been successfully realized using a birefringent filter Lyot as well as designing and optimizing optical thin films and the laser resonant cavity. The maximum output powers of the 895, 922, and 924 nm lasers are 2.01, 1.92, and 1.95 W, respectively. As far as we know, these are the highest power for Pr:YLF lasers at 895, 922, and 924 nm so far. The beam quality M-x(2) and M-y(2) factors are measured to be 1.85 and 1.71 at 895 nm, 1.94 and 1.67 at 922 nm, and 1.76 and 1.60 at 924 nm, respectively. The laser output power fluctuates within +/- 3%. In addition, the transmittance of the Lyot is theoretically calculated to achieve laser wavelength switching. The successful realization of the wavelength-switchable watt-level continuous wave near-infrared Pr:YLF laser can provide many practical applications in biomedicine and other fields.

We report an all-solid-state near-infrared single-frequency (single longitudinal mode, SLM) Pr3+:LiYF4 (Pr:YLF) laser with the spectral linewidth at the sub-picometer level. The SLM lasers with center wavelengths of 868 and 907 nm are realized in Pr:YLF crystal for the first time to the best of our knowledge. The maximum output powers of SLM lasers at 868 and 907 nm are 102  and 213mW, corresponding to the narrowest spectral linewidths of 82 MHz (0.21 pm) and 94 MHz (0.26 pm), respectively. At the maximum output power, the beam quality factors in the x and y directions are measured as 1.25 and 1.16 at 868 nm and 1.21 and 1.13 at 907 nm, respectively. The output power stabilities of the 868 and 907 nm SLM lasers are calculated as 1.39% and 0.87%, respectively. The successful realization of 868 and 907 nm all-solid-state SLM lasers makes up for the gap that the Pr:YLF SLM lasers developed in the past are focused on the visible region, enriches the types of near-infrared (NIR) SLM lasers, and can provide practical applications in biomedicine, cold atom physics, and optical atom manipulation.