Study On The Laser Performance Of Novel VB Group Mixed Crystal

Diode-pumped all-solid-state lasers have been widely used in various fields of scientific research and industrial application due to their advantages of compact structure,high efficiency and reliability.With the further application,the requirements of lasers are also improved.Therefore,it is critical to investigate the novel all-solid-state lasers.Meanwhile,traditional single crystals also face some problems such as small absorption bandwidth.Through replacing some ions with other similar ions,some novel mixed crystal could be grown successfully.Generally,the mixed crystals have a larger absorption bandwidth,a smaller emission cross section and a larger specific heat capacity.Therefore,this work is devoted to the research on the laser performance of the novel VB group mixed crystal.In this paper,the basic characteristics of mixed crystals were briefly introduced firstly,the research status was elucidated in detail.Based on the analysis of crystal heat source,the heat transfer equation in crystal was established and the heat distribution in the crystal was stimulated.The basic saturable absorption characteristics of Cr⁴⁺:YAG and two-dimensional?2D?materials were introduced.The size,thickness and nonlinear absorption characteristics of two kind of 2D materials were measured and fitted.In the experiment,the laser properties of Nd:GdYTaO₄,Nd:GdYNbO₄ and Nd:GdLaNbO₄ mixed crystals were demonstrated.Firstly,the spectral characteristics of these mixed crystals were investigated,and we could easily catch that the mixed crystals possess the advantages of larger absorption bandwidth and smaller emission cross section.Then continuous wave lasers were established via utilizing these three kinds of mixed crystals as the laser gain medium.The parameters of the laser were optimized under the different transmissions of output mirrors,different pump spot radius and different cavity lengths.Moreover,the laser intensity distributions under different power and the beam quality factors M² of the horizontal and vertical directions were measured and calculated.The repetition rate,pulse duration and average output power were detected when insetting Cr⁴⁺:YAG crystals with different initial transmissions,as well as the corresponding pulse energy and peak power were calculated to explore the relationship between the initial transmission of Cr⁴⁺:YAG and the parameters of the output pulsed laser.Finally,the pulse output was realized by the novel 2D materials of MoS₂ and WS₂ nanosheet and the characteristics of the pulse output laser were measured.Based on the results of experimental research,this work compared three kind of VB mixed crystals of Nd:GdYTaO₄,Nd:GdYNbO₄ and Nd:GdLaNbO₄.The niobate mixed crystals achieved higher slope efficiency since a wider absorption bandwidth.Furthermore,Cr⁴⁺:YAG with higher initial transmission would reach a higher average output power and repetition rate,while Cr⁴⁺:YAG with lower initial transmission resulted in a shorter pulse duration and higher peak power.By comparing two kinds of 2D materials,it was found that the MoS₂ nanosheet had a deeper modulation depth and the larger non-saturation loss which also led to a higher oscillation threshold.