Research On The Stability Of SBS Pulse Compression Based On The Interference Driving

ICF plays an important role in solving the energy crisis and the futurenational security issues and other aspects, which proposes a new shock ignitionand needs stable laser pulses of hundreds picoseconds. It is easier to operate,cheaper and can repair wave front distortion to access to high-quality laser outputpulses when using SBS pulse compression to obtain hundreds picoseconds laserpulses. Considering the poor compressed pulse stability and lack of systematicstudy on the stability of compressed pulse, the paper presents a new approach tostabilize output pulse width, in which the reverse pump laser interferes with theexcess pulse laser to drive the acoustic field. Compared with the normal approachto generate compressed pulses by SBS, the stability of compressed pulses will beimproved largely.In theory, on the basis of the general coupled wave equations on SBS,introducing the interference standing wave gets the SBS coupled wave equationsbased on the interference driving. Then program using the numerical model andsimulate the curve of Stokes pulse width and its stability with pump lightparameters and medium parameters. Estimating the ratio of reflected light in theSBS based on the interference driving. Establish acoustic field equations excitedby the interference standing wave and explore the influence of media phononlifetime, medium velocity and the slope of the pump light growth on the acousticfield intensity. The parameters above will provide reference for the experimentalanalysis.In the experiment, we adopt a structure of focused single cell based on theinterference driving, and use a convex lens and a plan mirror in place of theconcave mirror. Then build a light path of SBS pulse compression. The experimentdiscusses the influence of the parameters, including the pump intensity, focallength of the Short-focus lens, the distance between long-focus lens with SBS cell,reflectivity of the plan mirror and rotating the plan mirror (to make the normal ofthe plan mirror not collinear with the light path),on the compressed pulse width and its stability. According to the experimental results, it is consistent with thetheory basically.