Pr:YLF

Pr³⁺:YLF has been found as promising laser material for producing visible lasers directly. Many trivalent rare-earth ions (RE3) exhibit visible radiative transitions that potentially enable visibly emitting solid-state lasers. So far, various visible lasers based on RE³⁺-doped crystalline media have been demonstrated. Among them, trivalent praseodymium ion (Pr3) is recognized as one of the most successful active ions for achieving efficient visible lasers because the visible transitions of Pr³⁺ follow a four-level system, and their emission cross sections are larger than that of other RE³⁺. Many other RE³⁺ also exhibit visible transitions; however, these are often spin-forbidden, resulting in very small absorption and emission cross sections. Moreover, some visible transitions in RE³⁺ follow a three-level system, which is unattractive for laser demonstration. Only few laser materials have necessary properties for realization of lasing in visible spectral range. Trivalent praseodymium (Pr³⁺) is known to be an interesting laser ion for using with solid-state lasers in the visible spectral range because of its energy levels scheme, providing several transitions in the red (640 nm, ³P₀ to ³F₂), orange (607 nm, ³P₀ to ³H₆), green (523 nm, ³P₀ to ³H₅), and dark-red (720 nm, ³P₀ ³F₃₊³F₄) spectral regions.