Novel Saturable Absorber Q-Switched Solid-State Laser

Short pulse laser has a good application prospect in the field of laser ranging,laser processing,laser medical and other practical science and technology.Q-switched is the most commonly technique for short pulse laser achieved,and the key to realize laser operation of Q-switched is the saturable absorber,such as tungsten disulfide?WS₂?and molybdenum disulfide?MoS₂?and black phosphorus?BP?,etc.,have the characteristics of short recovery time,low saturation strength,wide operating bandwidth and high damage threshold,which suitable as a saturable absorber for short pulse laser.In this paper,considerations from the experimental and theoretical aspects,on the one hand,from the analysis of the physical and optical properties of materials,adopted the balanced twin-detector measurement technique to characterize the saturable absorption?SA?properties of the BP,WS₂ and MoS₂ solutions,and combined with the theoretical of pulse width calculation equation of passively Q-switched,which can obtained the theoretical pulse widths of Q-switched by different SA materials.On the other hand,from the experimental study of the comparison,Cr⁴⁺:YAG crystal and the solutions of WS₂ and MoS₂,were used in the Nd:YAG solid-state laser to achieve the short pulse width.And the results show that the SA solution has good output performance compared with the previous study in the Q-switched solid laser,and obtained a short pulse width is less than ten nanoseconds.Compared with the solid SA,the liquid SA has a good advantage in the heat dissipation and can effectively reduce the contact damage between the surface.In order to obtain a shorter pulse width,further optimization and improvement of the cavity structure and pump parameters,the output characteristics of the SAs solutions were studied in the same lasers.Finally,the pulse width of 2.86 ns,3.99 ns and 5.4 ns is realized in Q-switched Nd:YVO₄ lasers with BP,WS₂ and MoS₂,respectively.This is also the shortest pulse width in the Q-switched solid-state lasers of the three materials at the wavelength of 1064 nm.In addition,the 3.7 ns has been realized in Ti:sapphire laser by using MoS₂-SA.It is proved that the MoS₂-SA material has the characteristics of wide spectrum.