Output characteristics of $Nd^{3+}:YAG$ oscillator with Stimulated Brillouin Scattering phase conjugation mirror(SBS-PCM) was investigated. $Nd^{3+}:YAG$ rod was used as gain medium for lasing and two kinds of $Cr^{4+}:YAG$ were used as Q-switcher. SBS-PCM consisted of SBS-cell and lens system. The glass-tubing cell filled FC-75 index matching oil was used as SBS-cell.
Experiments were divided in two parts. The first part was perfomed using the plane output coupler(O.C., R=30%) scheme. For the case of no using Q-switcher, in Exp.-Ⅰ, energy characteristics resembled a free-runnng oscillator. In this case, SBS-cell didn't work as SBS-PCM because of low intensity in focal plane. For the case of using T=50% Q-switcher, in Exp.-Ⅱ, energy characteristics resembled a typical Q-switched oscillator. Pulse width was reduced from 65ns to 50ns by using SBS-PCM. For the case of using T=60% Q-switcher, in Exp.-Ⅲ, energy characteristics resembled a typical Q-switched oscillator. ANd pulse width was reduced to 20% of original case by using SBS-PCM. The second part was perfomed using the concave O.C.(r=50cm, R=30%) scheme. In Exp.-Ⅳ, pinhole was not used, nevertheless it was achieved that radial symmetry of output beam and that measured $M^2$ have value of 14.6. This setup had high output energy of 85% of plane O.C. case, but $M^2$=14.6 is not of the Gaussian mode. In Exp.-Ⅴ, pinhole was used, still it had radial symmetry of beam profile, and measured that $M^2$ had value of 1.26, the oscillator which has Gaussian mode output was achieved.
