Stimulated Brillouin scattering phase conjugate mirror (SBS-PCM) using purified liquid medium for high average input Текст научной статьи по специальности «Электротехника, электронная техника, информационные технологии»

LS-PS-13

Stimulated Brillouin scattering phase conjugate mirror (SBS-PCM) using purified liquid medium for high average input

S.Cha1, H.J. Kong1

1KAIST, Department of Physics, Daejeon, Republic of Korea

To achieve a laser inertial fusion energy, the laser fusion driver should operate at high repetition rate more than 10 Hz [1] and produce more than 100 kJ per one module [2]. One of the most promising techniques to make such laser system is coherent beam combining using stimulated Brillouin scattering phase conjugate mirror (SBS-PCM) [2]. The SBS-PCM has simple structure which consists of a cell and a feedback mirror, and it is good to compensate wavefront aberration by its phase conjugate property. Its feasibility was demonstrated in 2010 at the low power of 1 W [3], and the demonstration at the high power of 100 W class is on the progress.

One of the remaining issues to develop the SBS-PCM for the high energetic and high repetitive laser is the thermal issue in the SBS-PCM cell. At the high average input power of 100 W class with the high repetition rate over 1 kHz, the thermal load of the SBS liquid medium becomes a serious problem [4]. With high input power and a high repetition rate, the absorbed laser beam changes the refractive index of the SBS medium, defocuses the laser beam, and makes the convection or boiling in the liquid. This effect reduces the focal spot intensity of the input laser beam and degrades the SBS reflectivity in a liquid medium. If there are impurities in the SBS liquid media, this effect will become severe.

To resolve this issue, the authors chose HT-270 liquid as the SBS medium and are purifying the medium. The HT-270 liquid has the boiling temperature of 270°C and the high viscosity of 11.7 cSt, which is expected to make small convection. To test the medium, Kumgang laser system will be utilized [5]. The result will be shown in the conference.

References

[1] W. J. Hogan, et al., Energy from Inertial Fusion (International Atomic Energy Agency, Vienna, 1995), Chap. 3.

[2] H. J. Kong, S. Park, S. Cha, and M. Kalal, Opt. Mater. (Amst). 35, 807-811 (2013).

[3] J. S. Shin, S. Park, H. J. Kong, and J. W. Yoon, Appl. Phys. Lett. 96, 3-5 (2010).

[4] M. Nakatsuka, H. Yoshida, Y. Fujimoto, K. Fujioka, and H. Fujita, JKPS 43, 607-615 (2003).

[5] H. J. Kong, S. Park, S. Cha, H. Ahn, H. Lee, J. Oh, B. J. Lee, S. Choi, and J. S. Kim, High Power Laser Sci. Eng. 3, e1 (2015).