Design And Experimental Study Of Resonant Cavity Of Ti:Sapphire Femtosecond Laser

Solid-state femtosecond laser output pulses have the advantages of extremely short pulse width and extremely high peak power,and are widely used in industrial processing and scientific research.In femtosecond lasers,the main way to realize femtosecond lasers is to use Kerr lens mode-locking or passive mode-locking techniques based on semiconductor saturable absorption mirrors?SESAM?.Since the Kerr lens mode-locked operation is at the edge of the stable region of the resonator,the design of the cavity is extremely demanding and the performance of femtosecond laser depends largely on the design of the resonator.The preparation of SESAM requires expensive and complicated epitaxial growth techniques and cumbersome post-processing processes,and the production cost is high.Recently,two-dimensional transition metal carbon?nitrogen?compounds?MXene?materials have emerged,which not only have simple preparation process,low cost,but also have many excellent saturable absorption properties,providing a new platform for the development of femtosecond laser devices.Therefore,the development of laser cavity design methods and new saturable absorbers is of great significance.In this paper,theoretical and experimental studies on the design of Kerr lens mode-locked resonator are carried out,and the nonlinear optical properties of MXene saturable absorber are studied,and the Ti:sapphire ultrafast laser using MXene to start Kerr lens mode-locked is explored.The main research contents of this paper include the following aspects:1.Design theory of Kerr lens mode-locked resonator.A method of designing Kerr lens mode-locked resonator based on the graphic method of propagating circle is proposed.The method is simple,intuitive and easy to analyze,and has wide applicability.Using this method,two equivalent two-mirror resonator models which can realize Kerr lens mode-locking are given.The multi-mirror Kerr lens resonator can be easily obtained from this model.The theoretical limit peak power of the Kerr lens cavity is studied,and a peak of the mode-locked output of the Kerr lens is proposed.Finally,the numerical simulation of the Kerr lens mode-locked resonator designed by this method is carried out using ABCD matrix,which proves the correctness of the design method.2.Experimental study of solid-state femtosecond laser based on Kerr lens mode-locking.According to the above theoretical research results,we built a Kerr lens-mode-locked Ti:Sapphire femtosecond laser,which achieved a pulse center wavelength of 801.639 nm,a pulse width of 140 fs,a full width at half maximum of7.185 nm,a repetitive frequency of 82.3 MHz,and a signal-to-noise ratio of 40 dB.Highly stable femtosecond laser pulses with an average output of 519 mW.3.The stability and nonlinear optical properties of the carbon?nitrogen?compound?MXene?of the transition metal of two-dimensional materials were studied.The results show that the stability of Ti₃C₂T_x dispersed in heavy water solvent is better than that of isopropanol?IPA?solvent.In heavy water solvent,the dispersion of Ti₃C₂T_x is more uniform and there is no agglomeration;Ti₃C₂T_x has obvious saturable absorption characteristics near 800 nm band.Finally,Ti₃C₂T_x was built to start the Kerr lens mode-locked Ti:Sapphire mode-locked laser,and the Q-switched mode pulse was obtained.