Research On High Energy Picosecond SBS Laser

High-energy picosecond laser ultrashort pulses have high peak power,high beam quality,and ideal time and space waveforms,are used in many fields,such as medical,industrial processing,and military.Obtaining high-energy picosecond pulsed lasers using traditional techniques is costly,low efficiency,and has complicated experimental equipment,which is not conducive to popularization.Based on the stimulated Brillouin scattering(SBS)effect,high-energy hundred picosecond ultrashort pulse output was successfully obtained by means of compression and amplification of nanosecond pump light.Combine the laser with other systems to build a complete laser treatment instrument.Through the experimental observation of the tattoo reduction case samples,the feasibility and advancement of the experimental device were further verified.Firstly,the spontaneous scattering model and physical amplification model are established based on the SBS theory.The Maxwell equations and Navier-Stokes equations are combined to establish one-dimensional transient SBS coupled equations.Based on this,discrete equations of difference method and iterative method are used to obtain numerical simulation formulas.The SBS threshold effect is simulated.The pulse width compression and Brillouin amplification were simulated from three aspects: pump light,dielectric material and system structure.The effects of various parameters on pulse width compression,energy reflection and stimulated Brillouin amplification are analyzed numerically.Secondly,through the numerical simulation results and understanding of the properties of the medium,two kinds of media FC-40 and FC-43 were selected for comparison experiments.Build a dual-cell structure device that combines a generation cell with an amplification cell.The pulse width compression effect,energy reflection intensity,center wavelength and pulse width stability obtained were tested and compared.When FC-40 medium is used,Nd: YAG laser pulses with a pulse width of 6ns and a single pulse energy of 0-250 m J are compressed to obtain the narrowest pulse width of 296 ps,the highest energy of 145 m J ultrashort pulses,and the best energy reflectivity of 79.2%.With FC-43 as the medium,the experiment obtained a pulse width of 328 ps,the highest energy output was 143 m J,and the best energy reflectivity was 77.6%.Finally,the output picosecond laser is amplified(up to 800 m J).The SBS high-energy picosecond laser is used as the core,and the control system,cooling system and light guide system are combined to complete the construction of the whole machine.Samples of tattoo reduction experiments from plastic surgery department of Bethune First Hospital of Jilin University.The lightening effect was observed with an optical microscope.The results show that the high-energy picosecond pulsed laser based on the SBS effect has a better tattoo fade effect.