Solar-powered lasers

Graham-Rowe, Duncan

doi:10.1038/nphoton.2009.272

Cited by 53 publications

(29 citation statements)

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“…Since then, researchers have been exploiting both parabolic mirrors and Fresnel lenses to attain enough concentrated solar radiation at focal point and several pumping schemes have been constructed for enhancing solar laser output performances [1][2][3][4][5][6][7][8][9][10][11][12]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 single-crystal rods for solar laser operation, there still exist, in our opinion, some concerns about the advantages of Cr:Nd:YAG ceramic medium in solar-pumped lasers.…”

Section: Side-pumped Continuous-wavementioning

confidence: 99%

Side-pumped continuous-wave Cr:Nd:YAG ceramic solar laser

2013

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Abstract:To clarify the advantages of Cr:Nd:YAG ceramics rods in solar-pumped lasers, a fused silica light guide with rectangular cross-section is coupled to a compound V-shaped cavity within which a 7 mm diameter 0.1 at% Cr: 1.0 at% Nd:YAG ceramic rod is uniformly pumped. The highly concentrated solar radiation at the focal spot of a 2 m diameter stationary parabolic mirror is transformed into a uniform pump radiation by the light guide. Efficient pump light absorption is achieved by pumping uniformly the ceramic rod within the V-shaped cavity. Optimum pumping parameters and solar laser output powers are found through ZEMAX© non-sequential ray-tracing and LASCAD© laser cavity analysis codes. 33.6 W continuous-wave laser power is measured, corresponding to 1.32 times enhancement over our previous results with a 4 mm diameter Nd:YAG single-crystal rod. High slope efficiency of 2.6% is also registered. The solar laser output performances of both the ceramic and the single-crystal rods are finally compared, revealing the relative advantage of the Cr:Nd:YAG rod in conversion efficiency. Low scattering coefficient of 0.0018 cm-1 is deduced for the ceramic rod. Heat load is considered as a key factor affecting the ceramic laser output performance. Response to Reviewers: See attachmentAnswers to the Reviewers' comments:Dear Reviewer 1 Many thanks for your very helpful and insightful comments We would like to answer your comments one by one Reviewer #1: I believe that the paper presents an interesting result. However, there are many significant misunderstanding and unclear points which should be considered before further review.1. In Fig.5, they are comparing ceramic Cr.Nd YAG and Nd YAG crystal data but two conditions are completely Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporationdifferent. The size is different and input source is different. I doubt this comparison and it is not scientific. In addition, "Input solar power" in horizontal axis is misleading. They should put real incident solar power on the collecting mirror. The incident solar power of two experiments is almost 4 times different.With due respects, we think reviewer 1 has not been very careful in examining the manuscript.In Fig.5 Once again, the reviewer must have mistakenly compared the 10W/m2 collection efficiency with the 19.3 W/m2 value in Reference 8, which matches well with "a half of their previous result". Instead, our previous result in Ref. 10 was only 9.6W/m2 with the same PROMES-CNRS system, so the collection efficiency is slightly enhanced by using Cr:Nd:YAG ceramic rod in 2012.As mentioned in the manuscript, the total reflectivity of the whole solar energy collection and concentration system is only 59%. The back surface silver-coated plane mirror and parabolic mirror have more than 20 year´s service history. The collection efficiency can be largely improved by using front surface silver-coated mirrors.3. On page 3, they claimed the demerit of using optical fiber. However, I did not find the superiority of ...

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Section: Side-pumped Continuous-wavementioning

confidence: 99%

Side-pumped continuous-wave Cr:Nd:YAG ceramic solar laser

2013

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“…It has great potential for applications in hightemperature material processing, free-space power transmission, free-space laser communications, and so on. Recently, a solar-pumped laser has been proposed for the conversion of solar energy into chemical energy for storage in magnesium by reducing magnesium oxide to magnesium [1][2][3][4]. Although the idea of a solar-pumped laser is almost as old as the laser itself, laser output performance and conversion efficiency are still challenging issues.…”

Section: Introductionmentioning

confidence: 99%

“…They achieved laser output of about 500 W with a 660 m 2 heliostat, corresponding to collection efficiency ( laser output∕ primary concentrator area) of less than 1 W∕m 2 . Recently, more efficient and economical solarpumped lasers with Fresnel lenses have been investigated [1][2][3][10][11][12]. In such laser systems, so-called hybrid concentrator schemes, which comprise a conical mirror surrounding a rod containing the gain medium, have been employed.…”

Section: Introductionmentioning

confidence: 99%

Development of solar concentrators for high-power solar-pumped lasers

2014

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We have developed unique solar concentrators for solar-pumped solid-state lasers to improve both efficiency and laser output power. Natural sunlight is collected by a primary concentrator which is a 2 m×2 m Fresnel lens, and confined by a cone-shaped hybrid concentrator. Such solar power is coupled to a laser rod by a cylinder with coolant surrounding it that is called a liquid light-guide lens (LLGL). Performance of the cylindrical LLGL has been characterized analytically and experimentally. Since a 14 mm diameter LLGL generates efficient and uniform pumping along a Nd:YAG rod that is 6 mm in diameter and 100 mm in length, 120 W cw laser output is achieved with beam quality factor M2 of 137 and overall slope efficiency of 4.3%. The collection efficiency is 30.0 W/m2, which is 1.5 times larger than the previous record. The overall conversion efficiency is more than 3.2%, which can be comparable to a commercial lamp-pumped solid-state laser. The concept of the light-guide lens can be applied for concentrator photovoltaics or other solar energy optics.

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“…Solar-pumped lasers have gained an ever-increasing importance in recent years [1]. Compared to electrically powered lasers, solar laser is much simpler and more reliable due to the complete elimination of the electrical power generation and conditioning equipments.…”

Section: Introductionmentioning

confidence: 99%

“…Since then, researchers have been exploiting both parabolic mirrors and Fresnel lenses to attain enough concentrated solar radiation at focal point and several pumping schemes have been constructed for enhancing solar laser output performances [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. To improve the efficiency of Nd 3+ -doped YAG laser, cross-pumped Cr 3+ and Nd 3+ co-doped YAG ceramic material has attracted more attentions in recent years.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of Cr:Nd:YAG and Nd:YAG solar laser performances

2013

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To improve the efficiency of Nd 3+ -doped YAG solar laser, cross-pumped Cr 3+ and Nd 3+ co-doped YAG ceramic material has attracted more attentions in recent years. The sensitizer Cr 3+ ions have broad absorption bands in the visible region. Despite the interests in Cr:Nd:YAG ceramic medium, researchers have achieved significant laser efficiencies with different Nd:YAG single-crystal rods. While it is clear about the effectiveness of Nd:YAG single-crystal rods for solar laser operation, there still exist some concerns about the advantages of Cr:Nd:YAG ceramics in solar-pumped lasers. A 0.9 m diameter Fresnel lens is used as an economical solar collector. A 4 mm diameter, 25 mm length 1.0 at% Nd:YAG single-crystal rod and a 0.1 at% Cr: 1.0 at% Nd:YAG ceramic rod are pumped alternatively within a conical cavity through a secondary concentrator. With the Nd:YAG rod, the maximum laser power is 12.3 W, corresponding to 19.3 W/m 2 collection efficiency. With the Cr:Nd:YAG ceramic rod, the maximum laser power is 13.5 W, corresponding to 21.2 W/m 2 collection efficiency. This result is, to the best of our knowledge, the highest collection efficiency achieved with Cr:Nd:YAG ceramic medium. There is also a 109% increase in slope efficiency. In summary, we have experimentally observed a moderate, but not significant, advantage of Cr:Nd:YAG ceramics over Nd:YAG single-crystal medium in both solar laser conversion and slope efficiency.

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Solar-powered lasers

Cited by 53 publications

References 0 publications

Side-pumped continuous-wave Cr:Nd:YAG ceramic solar laser

Side-pumped continuous-wave Cr:Nd:YAG ceramic solar laser

Development of solar concentrators for high-power solar-pumped lasers

Comparative study of Cr:Nd:YAG and Nd:YAG solar laser performances

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