Fig. 1. Energy level structure of Pr^3+[11]

Fig. 2. Schematic diagram of intracavity frequency doubling experiment setup^[28]. OPS: optically pumped semiconductor; M1: input mirror (R=50 mm); M2: folding mirror (R=100 mm); M3: end mirror (R=50 mm)

Fig. 3. Schematic diagram of experimental setup^[50]. (a) 4.88 W high power high-efficiency orange laser, the cavity length is 51 mm, M1 and M2 are flat-concave mirrors with curvature radius of 50 mm; (b) 3.80 W high power orange laser with improved beam quality, the cavity is a 72 mm flat concave cavity, M3 is a flat concave mirror with curvature radius of 100 mm, and M4 is a flat mirror with tunable transmission

Fig. 4. Research status of several typical Pr:YLF continuous-wave visible lasers. The label for each marker corresponds to the output wavelength and the type of pump source used in the pumped Pr:YLF crystal

Fig. 5. Schematic diagram of the experiment of diode-pumped Pr:YLF with switchable wavelength near 670 nm^[57]

Fig. 6. Schematic diagram of diode-pumped Q-switched Pr:YLF visible laser using Bi₂Se₃ as SA^[73]. IM: input mirror, OC: output coupler

Fig. 7. Schematic diagram of Pr:YLF double pulse laser experiment setup^[79]

Fig. 8. Cavity configuration of the mode-locked Pr³⁺:LiYF₄ laser^[88]

Fig. 9. Layout of the Pr:YAlO₃ mode-locked laser system using the nonlinear mirror method^[92]

Fig. 10. Schematic of the passively mode-locked Pr:YLF laser with a SESAM and pumped by InGaN blue LDs^[94]

Fig. 11. Summary of Pr³⁺ doped crystal mode-locking in the visible range^[97]

Fig. 12. Diode pumped 604 nm and 607 nm quadratically polarized SLM-Pr:YLF laser experimental setup^[102]