The authors achieved 11%–14% slope efficiency of solar-pumped laser by Cr-codoped Nd:yttrium aluminum garnet ceramic and Fresnel lens focusing from natural sunlight. The laser output of 24.4W was achieved with 1.3m2 Fresnel lens. The maximum output for unit area of sunlight was 18.7W∕m2, which is 2.8 times larger than previous results with mirror collector. The utilization of Cr3+ ion enabled efficient absorption and energy transfer to Nd3+ ion of solar spectrum. The fluorescence yield at 1064nm for various pumping wavelengths was measured both for Crcodoped and nondoped laser media, and 1.8 times enhancement of laser output from sunlight is predicted.

A simple, compact, and efficient diode-side-pumped linear intracavity frequency doubled Nd:YAG rod laser with 50 ns pulse width and 124 W green output power Rev. Sci. Instrum. 81, 073104 (2010); 10.1063/1.3457000High-efficiency and economical solar-energy-pumped laser with Fresnel lens and chromium codoped laser medium Appl. Phys. Lett. 90, 261120 (2007); 10.1063/1.2753119Self-mode locking in a diode-pumped self-Q -switched green laser A solar pumped laser system with 7%-9% slope efficiencies has been developed. A Fresnel lens ͑2 ϫ 2 m, f = 2000 mm͒ is mounted on a two-axis sun tracker platform and focuses solar radiation toward laser cavity, which embraces Cr:Nd:yttrium aluminum garnet ceramic rod. The maximum emitted laser power is 80 W corresponding to maximum total area performance of 20 W / m 2 for the Fresnel lens area. This solar laser system would be used as a section of power plant in a magnesium energy cycle as a cost-efficient solar energy converter. Using direct solar radiation into laser, 4.3% net conversion efficiency has been achieved.

A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.

A new type of solar pumped laser system that has features of high-efficiency and low cost due to the use of a Fresnel lens and a Cr codoped Nd:YAG ceramic laser medium is reported in this paper. Slope efficiencies of 7 to 9% have been achieved. The laser output of about 80 W was achieved with the combination of a 4-m 2 Fresnel lens and solar light chamber as a secondary power concentrator. The maximum output from a unit area of the Fresnel lens was 20 W/m 2 , which is 2.8 times larger than the previous results with a mirror type concentrator.

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