High-flux solar photon processes

The solar pumped solid state laser is the system which changes sunlight into a laser. We are developing a solar pumped solid state laser for Space Solar Power Systems (SSPS) that require over 20 % effi ciency and a high-power. We designed a solar pumped laser system with over 20 % laser effi ciency in 2007. In this paper, fi rst, we describe the previous overseas solar laser development status. Next, we describe the previous domestic solar laser development status. Laser effi ciency using the sunlight is equal to or less than 1 % at domestically and abroad. Finally, we describe our solar pumped laser development.

Development of Solar-Pumped Solid-State Laser

Kanabe

Urano

2010

Concept Design of Space Solar-Pumped Solid-State Laser

Kanabe

Urano

Ogino

2010

Space Solar Power Systems (SSPS) required high-effi ciency and high-power solar pumped solid-state lasers. This research describes the concept design of the laser material and the laser collection mirror and laser of a space solar pumped solid-state laser by optimized calculation. The best of laser material is Cr/Nd:YAG ceramics. The absorption effi ciency was 88.7 %. The collecting mirror size was 200 m, the F-number is 1.3 and the collecting effi ciency was 92.3 %. The laser amplifi er is necessarily higher than a small signal gain of 5.2 to achieve higher more than 80 % of the aim extraction effi ciency when we assumed the temperature of the laser medium was 425 K. The highest optimized laser output strength was 3.8 kW/cm 2 , and the beam diameter was 32.5 cm. 21.0 % laser effi ciency was achieved.

Optical Energy Transfer from Cr3+ to Nd3+ and Fluorescence Properties in Yttrium Aluminum Garnet Ceramics

金邉

荻野

白濱

et al. 2010

Space Solar Power Systems (SSPS) collect solar energy and to ground by converting it into the laser. This system needs a broad absorption spectrum that can effi ciently absorb solar energy. Cr/Nd:YAG is doped with chromium (Cr 3+) as the sensitizer ion and neodymium (Nd 3+) as the activator ion. The sensitizer ion provides effi cient broad-band pump absorption and transfers the excitation energy to the activator ion. This process effects changes the fl uorescence properties of the laser material. This research describes the fl uorescent characteristics of Cr/Nd:YAG ceramic including this energy transfer process.