Some Study On The Ablation Of Cu Using Shaped Femtosecond Pulse

In this paper,shaped femtosecond pulse was used to ablate single crystal copper,and the morphology of the pits and the intensity of fluorescence signal were studied.It is found that under the same energy condition,the number of sub pulses and the time interval between the adjacent sub pulses will affect the shape of ablation pit and the intensity of fluorescence signal.The number of sub pulses will affect the energy distribution,which directly affects the formation of ablation pit and plasma;the distance between adjacent sub pulses will affect the time of energy injection into the sample or plasma.For a pulse sequence with multiple subpulses,the first subpulse interact with the sample to liquefy or vaporize,and the liquefying or vaporizing sample will better couple the subsequent subpulses and interact with each other.Therefore,by changing the number of shaping pulses and the time interval between adjacent pulses,the ablation of the preceding pulses is first determined.The plasma produced by ablation expands continuously with time,and the expanded plasma will block the subsequent pulses,but the expansion of the plasma will weaken after a certain time,and its blocking effect on the subsequent pulses will also be reduced.When the plasma produced by the preceding subpulse is occluded,part of the energy of the subsequent subpulse will continue to ablate the sample through the plasma,and part of the energy will be absorbed by the plasma to reheat the plasma.Generally speaking,multi pulse sequence ablation is a very complex process,but by adjusting the number of sub pulses of multi pulse sequence and the time interval between adjacent sub pulses,the ablation morphology can be controlled to a certain extent,which is very instructive for the application of femtosecond laser.