Efficient 38.8 W/m² solar pumped laser with a Ce:Nd:YAG crystal and a Fresnel lens

Abstract

Herein, we report a significant improvement in solar-pumped laser collection efficiency based on end-side pumping a 6-mm-diameter 95-mm-length Ce:Nd:YAG/YAG grooved bonded crystal rod. A Fresnel lens, quartz cooling-water tube, and gold-plated conical cavity constituted the solar-energy collection and concentration system, which was designed to maximum pump light absorption and minimize thermal effects in the Ce:Nd:YAG laser medium. To the best of our knowledge, this is the first time that a Ce:Nd:YAG crystal has been pumped by a Fresnel-lens solar-energy collection and concentration system. The 0.69-m2 effective solar-collection area produced 26.93 W of continuous-wave laser power, corresponding to 6.33% slope efficiency. The collection efficiency (38.8 W/m2) was 1.21 times higher than the highest previously reported value for Fresnel-lens solar collection, and is a record for single-beam solar-pumped lasers.

Seven-grooved-Ce:Nd:YAG-rod solar laser pumping approach with 34.5 W/m2 TEM00-mode collection efficiency

“…The Ce:Nd:YAG active medium has demonstrated itself to be more proficient at improving the solar laser performance when compared to the Nd:YAG medium 11 , 13 , 27 , 33 – 35 In the wavelength ranges of ultraviolet and blue, not only do the Ce3+ ions strongly absorb the sunlight, but also the energy transfer from the Ce3+ to the Nd3+ ions is efficient.…”

“…This corresponded to collection and conversion efficiencies of only 2.93 W/m2 and 0.33%, respectively. For multimode operation, the current experimental record was attained in 2023 from a system comprising a 0.94 m diameter Fresnel lens, a conical cavity, and a quartz tube, end-side-pumping a grooved Ce:Nd:YAG/YAG bonded crystal rod 13 . 26.93 W cw laser power, 38.81 W/m2 collection efficiency, and 3.88% conversion efficiency were reached.…”

Solar laser pumping approach for both simultaneous and stable multibeam operation under tracking error condition

“…In recent years, solar laser researchers have used both parabolic mirrors and Fresnel lenses as primary concentrators to improve collection and conversion efficiencies. [14][15][16][17][18][19] Cai et al 20 improved the single-rod solar laser collection efficiency to the state-of-the-art of 38.8 W/m 2 by pumping a 6-mm diameter, 95-mm length Ce:Nd:YAG rod through a Fresnel lens. Still, the solar-to-laser conversion efficiency of 3.9% was lower than the state-of-the-art single-rod solar-to-laser conversion efficiency of 4.5% attained by Garcia et al from a 2.5-mm diameter, 25-mm length Ce:Nd:YAG rod efficiently pumped through a parabolic mirror.…”

“…In recent years, solar laser researchers have used both parabolic mirrors and Fresnel lenses as primary concentrators to improve collection and conversion efficiencies 14 – 19 Cai et al 20 . improved the single-rod solar laser collection efficiency to the state-of-the-art of 38.8 W/m 2 by pumping a 6-mm diameter, 95-mm length Ce:Nd:YAG rod through a Fresnel lens.…”

“…Then, in 2022, a dual-rod side-pumping prototype was experimentally studied, achieving up to 1.40 deg TEW10% in the vertical configuration; however, the side-pumping approach seriously limited the solar laser efficiency of the system 49 . End-side-pumping configurations lead to higher efficiencies; 18 , 20 , 21 , 34 however, focusing the concentrated solar radiation onto the end face of a single laser rod is not favorable for enhancing the solar tracking error compensation capacity 49 . Therefore, in the same year, Catela et al 50 .…”