Beam combination using stimulated Brillouin scattering phase conjugate mirror for laser fusion driver

Abstract

For practical laser fusion energy (IFE) generation, a M-J laser driver is required with a repetition rate of over 10 Hz. Achieving an IFE driver with this high repetition rate requires reduction of the thermal load of the laser system. Several methods have been developed for this goal, such as beam combination, the gas-cooled, diode-pumped laser, the electron beam pumped gas laser, and the large-sized ceramic Nd:YAG. The beam-combination technique using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCM) is a promising one among these techniques for the IFE driver. The beam-combination laser system does not need a large-gain medium, so it can be operated at a repetition rate exceeding 10 Hz, regardless of the output energy. Moreover, it is easily adaptable to the modern laser technology. We propose a beam-combination laser with SBS-PCMs whose energy can be freely scaled up by increasing the number of separate amplifiers, and also demonstrate the practical and efficient phase control of SBS waves which is essential in a beam-combination laser using SBS-PCMs. In this paper, recent theoretical and experimental results on phase control and a beam-combination laser for developing the IFE driver are discussed in detail.