Investigation Of Gain Properities Of Non-collinear Brillouin Amplification System

Inertial Confinement Fusion provides a new way for human to cope with theenergy crisis and has been concentrated on all around the world for its tremendousenergy generation. In our country’s ICF system, hundred picoseconds level pulseamplification adopts the technique of stimulated Brillouin scattering. Collinear Brillouinamplification technique has been used for many years for relatively higher amplificationefficiency, but for should be used to separate amplified single pulse from light road ofthe polarizer whose big one is difficult to be made and processed, it will not be betterthan non-collinear style which can provide this kind of problem a new approach whichseparates the single by transmission along its own way for some distance. But manyparameters will be influenced by the degree, so investigation of the generation andmechanism of these influences is a really important thing.This paper begins with the acoustic equation, combining it with the knowledge ofclassical electrodynamics, and then obtains the formula of gain coefficient changingwith the degree. The theory imitation shows that gain spectrum under different degreehas its own peak value, and it increases with the incteasing of the degree, so this resultis good for non-collinear Brillouin amplification. Then, with the same approach,equivalent interaction length is obtained which is used for converting non-collinear styleto collinear style to solve the problem as energy transmission efficiency. Its theoryimitation shows that equivalent interaction length under Brillouin frequency shift isdecreasing with the increase of degree, but shows different trend of decreasing, underthe condition of material selected with short phonon time it will not decrease obviously,so it is proved to be feasible to non-collinear Brillouin amplification.Under the condition of neglect of the interaction between different points of thetransverse of the light beam, the method of establishment of three-dimensionalstimulated Brillouin scattering model has been provided. The basic idea of it is thatthere is no essential difference between collinear and non-collinear, and the collinearamplification is a particular condition of non-collinear.Finally, experiment is carried out to demonstrate the trend of the gain coefficientchanging with the degree, the experiment result is relatively fit with theory, but there isdifference of the value between them. So according to this difference, error analysis inquality is showing in the end.