Study Of The Laser Properties Of The Pr³⁺:YLF Crystal

In this paper the laser properties of the Pr-doped crystal was studied. Pr is the abbreviation of Praseodymium, which is rare-earth element. Due to its energy level configuration, trivalent Pr-ion offers several transitions in the visible region. Laser sources emitting in the visible range can be very useful in many fields such as data storage, medical treatment, laser communication under water and so on. And ultraviolet laser, frequency doubled from these visible lasers, can be useful in fields such as laser print, laser drilling, laser cutting, atmospheric measurements and even biomedical applications. On the other hand, all solid-state lasers have been paid more attention to in recent years regarding that they are smaller, life-longer, more stable, and more efficient. Therefore Pr-doped crystal has special advantages in the field of solid-state visible laser. This paper studied the laser properties of the Pr-doped crystal hoping to push forward the development of solid-state lasers and benefit people's searching for new laser sources.We measured the fluorescent line of Pr³⁺:YLF crystal, showing that Pr³⁺:YLF crystal had seven emission peak-479.3nm, 522.7nm, 546.1nm, 607.1nm, 639.4nm, 697.5nm and 720.8nm, and the highest emission peak was 604nm and 640nm. The result showed it was feasible to use Pr³⁺:YLF crystal as the active medium of solid-state visible laser. Then the absorption spectrum of Pr³⁺:YLF crystal was measured, showing that Pr³⁺:YLF crystal had five absorption peak-442nm,467nm,479nm,584nm and 596nm, and the highest absorption peak was 442nm. The result provided reference for selecting proper pump wavelength.It was nacessary to do simulation before experiment. In light of the theory of four-level rate equation, the paper did optimization design for the Pr³⁺:YLF laser and mainly studied the output power as function of the crystal length and the transmissivity of the output mirror, finding that there was a optimized transmissivity under a certain crystal length, to obtain a highest output power.At last, the experiment of Pr³⁺:YLF crystal emitting laser was carried out. Pumped by 442nm pulse laser provided by a dye laser diveces, we successfully obtained red laser, of which the wavelength was 640nm and the highest output energy was 142μJ. We also measured the output energy and the slope efficiency of this Pr³⁺:YLF laser under several output mirror transmissivities which were 3%,5%,7% and 10%. We compared the experiment results with the simulation results, analysed the discrepancy and advised how to improve Pr³⁺:YLF laser in the future.