Nd-doped phosphate glass laser systems for laser-fusion research

Nd:phosphate laser glasses are evaluated in this paper as the active medium for high-power and high-energy laser systems for laser-fusion research. Small-signal gains and parasitic limits of rod amplifiers and disk amplifiers are first shown. Then system performances at a short-pulse, high-power regime and at a long-pulse high-energy regime are investigated. At a short-pulse regime, very high output power of 3.4 terawatts (TW) has been obtained because of the large stimulated emission cross section and the small nonlinear refractive index. At a long-pulse regime, we found that the effective saturation fluence of the phosphate glass LHG-8 is 4.0 J/cm2and we can efficiently extract the energy stored in the laser glass. This lead to the conclusion that Nd: phosphate glasses are very suitable for short-pulse as well as for long-pulse amplifications. In this paper, system descriptions and hardware specifications of the glass laser systems at the Institute of Laser Engineering (ILE), Osaka, University, are also briefly given.