Influence of Focal Length on Optical Limiting Characteristics Based on Stimulated Brillouin Scattering in CCl4 Medium

The influence of focal length on optical limiting power characteristics based on stimulated Brillouin scattering in CCl₄ medium is investigated numerically and experimentally. The simulation results show that, the characteristics of limiting power and pulse shape are controlled mainly by focal length when other parameters are fixed. When focal length is short, for example 5 cm, the characteristic of limiting power and pulse shape is close to ideal. In experiment, focusing 8 ns, 1064 nm, 16 mJ pulses into CCl₄ medium, the rules of limiting power and pulse shape versus focal length are investigated. The experimental results are in good agreement with the conclusions of theoretical simulations.