A 40 W cw Nd:YAG solar laser pumped through a heliostat: a parabolic mirror system

Abstract

Solar-pumped solid-state lasers are promising for renewable extreme-temperature material processing. Here, we report a significant improvement in solar laser collection efficiency by pumping the most widely used Nd:YAG single-crystal rod through a heliostat-parabolic mirror system. A conical-shaped fused silica light guide with 3D-CPC output end is used to both transmit and compress the concentrated solar radiation from the focal zone of a 2 m diameter parabolic mirror to a 5 mm diameter Nd:YAG rod within a conical pump cavity, which enables multi-pass pumping through the laser rod. 40 W cw laser power is measured, corresponding to 13.9 W m −2 record-high collection efficiency for the solar laser pumped through a heliostat-parabolic mirror system. 2.9% slope efficiency is fitted, corresponding to 132% enhancement over that of our previous pumping scheme. 209% reduction in threshold pump power is also registered.

A fully planar solar pumped laser based on a luminescent solar collector

“…In addition, SPLs could play a critical role in a more sustainable magnesium energy cycle, reconverting magnesium oxide to magnesium 2,9,10 . Although many improvements in the optical gain medium and solar collector design have been reported since the first demonstration of an SPL 11 , most SPLs still rely on lens or mirror concentrator systems with concentration factors on the order of thousands to obtain sufficient gain in the irradiated active medium [12][13][14][15][16][17][18] . Such concentration optics limit the practicality of SPLs because they are expensive and require very precise tracking of the sun to keep the focal point on the active medium to within 0.01°1 9 , which is challenging at high winds.…”

Thermal loading effects on Nd:YAG solar-laser performance in end-pumping and side-pumping configurations: a review

“…For clearly exhibiting the thermal loads effects on Nd:YAG solar-lasers performance, research details will be given afterward. Some literatures [1][2][3]6,7,9,[21][22][23][24][25][26][27][28][29] were made for the solar-laser efficiency improvement, whereas others included laser beam quality enhancements. 11,[26][27][28][30][31][32][33][34][35] Research details will be given for both multimode and monomode (fundamental-mode) solar-laser operations, respectively.…”

Side-pumping Nd:YAG solar laser by six Fresnel lenses

“…Despite the small overlap between the Nd:YAG absorption spectrum and the solar spectrum, Nd:YAG has been demonstrated as the best material under solar pumping because of its superior characteristic on thermal conductivity, high quantum efficiency and mechanical strength compared to other host materials [2][3][4][5][6][7][8][9][10][11]. For 1.1 at% Nd 3+ -doped YAG single-crystal medium, 22 absorption peaks are defined in ZEMAX TM numerical data.…”

“…Parabolic mirrors have been exploited to achieve tight focusing of incoming solar radiation [2][3][4][5]. 13.9 W/m 2 collection efficiency has been achieved at the PROMES-CNRS (Odeillo, France) in 2012, by pumping a Nd:YAG single-crystal rod through a heliostat -parabolic mirror system [6]. This value is, to the best of our knowledge, the highest solar laser collection efficiency achieved with parabolic mirrors.…”