Measurement of the threshold of nonfocusing-pumped stimulated Brillouin scattering based on temporal characteristic of the reflected pulse

摘要

We present a novel method for measuring the threshold of stimulated Brillouin scattering with large-aperture super-Gaussian-shaped laser pulses transmitting in a nonlinear medium. From the differences between the waveforms of reflected light below and above the SBS threshold and the "energy in the bucket" method, threshold pump intensity can be determined clearly. Experiment is carried out with a high-power Nd:glass laser system of 527 nm wavelength, used as the light source that delivers 3 ns super-Gaussian-shaped pulses, and the nonlinear medium FC-40. The experimental results agree well with the numerically calculated results, and the SBS threshold in this case is 780 MW/cm~2.