The stimulated Brillouin scattering (SBS) media perfluorinated amines with good SBS characteristics have been discovered based on the dependence of SBS characteristics on the chemical structures. The SBS parameters of perfluorinated amines such as FC-131, FC-3283, FC-40, FC-43 and FC-70 have been measured or calculated. The results demonstrate that their absorption coefficients are below 10-3cm-1 and optical breakdown thresholds are above 100GW/cm2. The perfluorinated amines also exhibit a series of unique physicochemical properties, i.e., non-toxic property, low volatility, and high stability. The discovery not only diversifies the SBS media, but also improves the performance of SBS system, thereby laying a good foundation for the application of SBS phase conjugation mirror in high-power laser systems.

Adopting noise initiation model of stimulated Brillion scattering (SBS), the characteristic of transmitted energy and power in CS2 liquid media under non-focusing pump is investigated numerically. The results show that, the waveform of transmitted pulse with increasing input energy shows the characteristic of power limiting. And the transmitted energy varies linearly with input energy withont the energy limiting effect. When 1053 nm 20 ns Nd:YLF laser was used as pump in a 3∶1 inverse expansion system are using attenuators to adjust input energy in the rang of 2 to 92 mJ, the rules of transmitted energy and waveform versus input energy are acquired, and compared with the results of focusing pump. The experimental results are in good agreement with the theoretical simulations. Because the optical breakdown takes place at high input energy under focusing pump, the power limiting with non-focusing pump is applicable under the circumstances of high power and energy.

This paper proposes a method for measuring the stimulated Brillouin scattering (SBS) threshold based on waveform variation of SBS optical limiting. The output waveforms for different pump power densities are numerically simulated, and validated in the Nd:YAG seed-injected laser system. The results indicate that SBS does not take place in the case of a low pump power density and thus the output power scales up linearly with pump power. Once the pump power density exceeds the SBS threshold, SBS takes place and thereby the energies are transferred from pump to Stokes. As a result, a small shoulder appears in the trailing edge of the output waveform, which provides another method to determine the SBS threshold.

This paper reports that the pattern formation in homogeneous solutions of polyisoprene in toluene saturated with C60 induced by a continuous-wave visible laser is observed experimentally. The transmitted beam patterns change with the increase of the laser irradiation time. In the initial phase, the patterns with concentric ring-shaped structure are formed. In the end, the patterns become speckle-shaped. The incubation time of the transmitted beam widening is inversely proportional to the laser power density and solution concentration. The pattern formation results from the optical-field-induced refractive index changes in the solutions, but the mechanism of optical-field-induced refractive index changes in the polymer solutions needs to be further studied.

Adopting noise initiation mode of stimulated Brillion scattering (SBS), the influence of focal length on optical limiting power and energy is numerically simulated. It shows that the characteristic of limiting power and energy are controlled by focal length. When focal length is moderate, say 15cm, the limiting energy is lowest. When focal length is short, say 5cm, the characteristic of limiting power is close to ideal. In experiment, focusing 8ns, 1064nm, 16mJ pulses into CCl4 medium, the variation of limiting power and energy versus focal length is investigated. The experimental results are in good agreement with the conclusions predicted by the simulations.