Investigation Of Supercontinuum Radiation And Femtosecond Filamentation In Fused Silica By Using Conical Lens

When the ultrashort pulse laser power is greater than its self-focusing critical power in optical media,the laser will form plasma filament due to the dynamic balance between the nonlinear Kerr self-focusing and plasma defocusing effects.The filament has a very broad application due to its unique advantages in many research fields.In the different fields of femtosecond laser filamentation,the conical lens is often chose as a focal element which has a very important property of long focal depth to control filamentation.Firstly,a brief overview of femtosecond filamentation is introduced,in which the latest research progress of using conical lens in different nonlinear media(gas,solid,liquid)to optimize the filament and supercontinuum radiation is commented.Furthermore,the physical mechanism of using conical lens to control femtosecond filamenation is discussed with the help of Zemax software.We simulated the variation of the focal depth of the Bessel beam with the increase of the distance between the concave lens and the conical lens.In the experiment,the influence of experimental parameters(the distance between the concave and conical lens,the angle of the cone lens and the incident laser energy)on the plasma filament and the supercontinuum radiation is studied.The results show that the combination of concave lens and conical lens can be used to optimize the control of plasma filament and supercontinuum radiation,which could provide a convenient method in many research fields.