Effect of focal intensity on stimulated-Brillouin-scattering reflectivity and fidelity

We have measured the reflectivity and phase-conjugate fidelity of stimulated Brillouin scattering in hexane while varying the pump power and aberration. By directly measuring the reduction in focal intensity that is due to aberrations, we found that the reflectivity and the fidelity depend solely on the focal intensity. We were able to vary the strength of aberration, producing up to a factor-of-30 reduction in focal intensity. The reflectivity and fidelity decreased monotonically with decreasing focal intensity. There was no minimum amount of aberration required for accurate wave-front reversal, and the maximum amount was the aberration that reduced intensity to near threshold.