【作者】 陈波；

【导师】 刘善德；

【作者基本信息】 山东科技大学 ， 电子科学与技术， 2023， 硕士

【摘要】 脉冲激光在激光医疗、激光雷达、大气探测、工业加工以及光电对抗等领域都具有十分重要的应用价值。近年来,具有可饱和吸收特性的低维材料已成为推动脉冲激光发展的重要因素,探索具有优异性能的可饱和吸收体(Saturable absorber,SA)仍然为当前激光领域的一大研究热点。金属纳米材料作为一种新型的可饱和吸收体表现出了优异的可饱和吸收性能,引起了人们的广泛关注。尤其是液态金属纳米材料,因其熔点低、热导率高、流动性好、成本低廉等优势展现出了比金、银等固态金属纳米粒子更为广阔的应用空间。同固态金属纳米材料相同,其非线性光学特性也是由局域表面等离子体共振效应(Localized surface plasmon resonance,LSPR)引起的,通过控制纳米结构的尺寸及形状,可以改变材料对不同光波段的吸收,进一步能实现材料的宽带吸收。因此可以将其应用到激光器中,为可饱和吸收体的发展注入新的活力。本论文以液态金属GaInSn纳米球为研究对象,探索了其制备方法,系统表征了其非线性光学特性,并将其作为可饱和吸收体应用到可见光和中红外波段全固态激光器中,实现了稳定的脉冲激光输出,证明了该材料在光调制方面具有优异的性能。具体内容如下:(1)对全固态脉冲激光器进行了介绍,阐明了本论文的研究意义;对本论文所用的增益介质进行了详细的说明,并从新型低维可饱和吸收体材料出发,总结了金属纳米材料在激光领域的应用现状。(2)从非线性光学的角度阐述了可饱和吸收的机理,随后主要针对表征材料非线性光学特性常用的技术方法—Z扫描技术展开了讨论,包括对Z扫描技术的基本原理、实验装置以及结果分析进行了详细的介绍。(3)实现了基于液态金属GaInSn纳米球的可见光调Q激光输出。首先使用超声法制备了高质量的GaInSn纳米球可饱和吸收体。分别使用扫描电子显微镜(Scanning electron microscope,SEM)和透射电子显微镜(Transmission electron microscope,TEM)对其微观形貌进行了观测,结果显示制备的GaInSn纳米球材料具有良好的均匀性;随后使用开孔Z扫描技术对其非线性光学特性进行了表征,在可见光波段,获得了GaInSn纳米球的调制深度和饱和通量分别为35.5%和21.75m J/cm~2;最后,利用该材料实现了稳定的639 nm调Q脉冲激光输出,获得了280 ns的最窄脉冲宽度和174.8 kHz的最高重复频率,验证了液态金属GaInSn纳米球在可见光波段优异的可饱和吸收性能。(4)实现了基于液态金属GaInSn纳米球的中红外调Q激光输出。首先在中红外波段使用开孔Z扫描技术对GaInSn纳米球材料的可饱和吸收特性进行了表征,测得其调制深度和饱和通量分别为34.3%和0.497 GW/cm~2;随后实现了基于该材料的中红外脉冲激光输出,获得最窄脉冲宽度为500 ns,最高重复频率为67 kHz。证明了液态金属GaInSn纳米球在中红外波段的光调制能力以及在超短脉冲激光器中的应用潜力。更多还原

【Abstract】 Pulsed lasers possess very important applications in laser medicine,LIDAR,atmospheric sounding,industrial processing,and optoelectronic countermeasures.In recent years,low-dimensional materials with saturable absorption properties have become an important factor driving the development of pulsed lasers.The exploration of saturable absorbers(SA)with excellent performance is still a major research hotspot in the laser field.As a new type of saturable absorber,metal nanomaterials have shown excellent saturable absorption properties,which have attracted a lot of attention.In particular,liquid metal nanomaterials show a broader application space than solid metal nanoparticles such as gold and silver due to their advantages of low melting point,high thermal conductivity,good mobility,and low cost.Similar to solid metal nanomaterials,their nonlinear optical properties are caused by the local surface plasmon resonance(LSPR)effect,and by controlling the size and shape of nanostructures,the absorption of the material can be changed,which can broaden the absorption bandwidth of the material.Therefore,it can be applied to lasers to inject new vitality into the development of saturable absorbers.In this thesis,we explored the preparation method of liquid metal GaInSn nanospheres,systematically characterized their nonlinear optical properties,and applied them as saturable absorbers to all-solid-state lasers in the visible and mid-infrared bands,achieving stable pulsed laser output and demonstrating the excellent performance of the material in light modulation.Details of the research are as follows:(1)Firstly,the all-solid-state pulsed laser is introduced,and the significance of this research is expounded.Subsequently,the gain medium used in this thesis is described in detail,and the application status of metal nanomaterials in laser is summarized in terms of new low-dimensional saturable absorber materials.(2)The mechanism of saturable absorption is described from the perspective of nonlinear optics.Then,the Z-scan technology,which is commonly used to characterize the nonlinear optical properties of materials,is discussed,including the basic principle,experimental equipment and result analysis of Z-scan technology are introduced in detail.(3)Visible Q-switched laser output based on liquid metal GaInSn nanospheres is realized.The first is the preparation of GaInSn nanospheres.High quality GaInSn nanospheres are prepared by ultrasonic method.Scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to observe the microscopic morphology of the GaInSn nanospheres,and it was found that the prepared GaInSn nanospheres material had good uniformity.Subsequently,the nonlinear optical properties were characterized using the open-aperture Z-scan technique,and the modulation depth and saturation fluence of GaInSn nanospheres were obtained to be 35.5%and 21.75 m J/cm~2 in the visible band,respectively.Finally,a stable 639 nm Q-switched pulsed laser output was achieved using this material,and the shortest pulse width of 280 ns and the highest repetition rate of 174.8kHz were obtained,which verified the excellent saturable absorption performance of liquid metal GaInSn nanospheres in the visible band.(4)The mid-infrared Q-switched laser output based on liquid metal GaInSn nanospheres was realized.First,the saturable absorption properties of GaInSn nanospheres were characterized in the mid-infrared band using the open-aperture Z-scan technique,and the modulation depth and saturation fluence were measured to be 34.3%and 0.497 GW/cm~2,respectively.Then,the mid-infrared pulsed laser output based on this material was realized with the shortest pulse width of 500 ns and the highest repetition rate of 67 kHz,which demonstrate the optical modulation capability of GaInSn nanospheres in the mid-infrared band and the potential for applications in ultrashort pulsed lasers.更多还原