604-nm high-order vortex beams directly generated from a Pr:YLF laser with a cavity-loss-induced gain switching mechanism. (July 2020)

• Record Type: Journal Article
• Authors: Luo, Saiyu; Cai, Zhiping; Sheng, Chuanxiang; Li, Li; Chen, Qian
• Is Part Of: Optics & laser technology. Volume 127(2020)
• Publication Date: 2020-07
• Subjects: Interference -- Laser modes -- Optical pumping -- Optical resonators; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2020.106185
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: First demonstration of 604-nm vortices directly generated from a Pr:YLF laser. Topological charge up to three was achieved through designated cavity design. Cavity-loss-induced gain switching mechanism between 604 and 607 nm emission. Output power reached 470, 230, and 60 mW for the 1st-, 2nd-, and 3rd-order vortex. Slop efficiencies were 24.5%, 17.5%, and 11.4%, respectively. Abstract: In this work, we demonstrated, for the first time to the best of our knowledge, high-order vortex beams at 604 nm that were directly emitted from a Pr:YLF crystal laser. By combining a blue-diode-pumped v-type cavity for controllable Gouy phase introduction and off-axis crystal rotation for high-order HG modes generation, topological charged 604-nm vortex lasers were attained up to the third order. Furthermore, the vortex beams were found to be lasing at 604 nm that was often deemed less prone to lase compared with 607-nm in the same energy manifold. By a detailed spectroscopic study and rate equation analysis, we proposed and confirmed that the 604-nm transition of Pr:YLF crystal could be favorable in the vortex beam generation by a cavity-loss-induced gain switching process, in which the net gain at 604-nm could surpass that of 607-nm as the cavity loss was amassed beyond a threshold value.