Temperature And Beam Conditions Effects On Supercontinuum Generation Using Femtosecond Laser

In recent years, with the rapid development of laser technique, the study of interaction between femtosecond laser and material has attracted a lot of interest. In this paper, the super continuum radiation generated by femtosecond laser CuSO₄ solution is studied. The development of laser technology and the application of femtosecond laser are introduced in this paper. Next, the transmission mechanism of the femtosecond laser in the medium is introduced, and some nonlinear phenomena in the process of transmission are introduced. In the experiment, this thesis mainly studies the filamentation in CuSO₄ solution of supercontinuum generation by femtosecond laser. By changing the internal CuSO₄ solution?concentration, temperature? and external conditions?mainly by single lens and micro lens array focusing? on supercontinuum generation are analyzed, a comprehensive study of the effects of various experimental parameters on the supercontinuum, and draw experimental condition to obtain the flat spectrum. Experimental results show that the appropriate laser energy, CuSO₄ solution concentration, focusing lens, focusing position, temperature and so on to control the ultra continuous spectrum, and then obtain a relatively flat spectrum. Shadow imaging experiment of filamentation further found that in single lens laser filamentation under the condition that the laser energy deposition in CuSO₄ solution less than hundred micro joules, otherwise, the emergence of a large number of gas bubbles in the process of solution. These bubbles will affect the spinning stability and improve the strength of supercontinuum. In order to overcome the single lens, focusing on the laser energy is too high, the liquid in the bubble, can not get a high intensity of the super continuum spectrum of this problem, we use the micro lens array of copper sulfate solution in the ultra continuous spectrum. It is found that the use of micro lens array can improve the injection energy, effectively reduce the bubble, to a certain extent, improve the intensity of the super continuum, but not conducive to the flat spectrum.