Study On Mode-locked Fiber Lasers Based On A New Type Of Gold Nanomaterials

Mode-locked fiber laser has been used in optical fiber communication,optical sensor,materials,medicine and the fields of national defense because of their high peak power,high pulse energy,simple structure and good stability.In recent years,many researchers have made in-depth studies on the introduction of new saturable absorbers in fiber lasers to achieve mode-locked laser output.Gold nano-materials own high non-linearity,ultra-fast response time and good fiber compatibility,and it's easy to prepare.In addition,the pulse laser output can be achieved by using the saturable absorption properties of gold nanomaterials.So,the saturable absorber based on gold nanomaterials has caused wide attention.Gold nanomaterials have also applied in the fields of optical information storage,biomedicine,the research of new energy and so on.We prepared gold nanomaterials with different morphologies and sizes to study the saturable absorption properties of the gold nanomaterials.We found that gold nanometer biconical and gold nanorod films with different aspect ratios own saturable absorption in corresponding bands,which might be used in visible-infrared band Q-switched or mode-locked lasers.Based on the above findings,we have prepared gold nano-double cone solution and gold nanorod solution,respectively,in the experiment we have also made the fiber-integrated saturable absorber based on gold nano-double cone and gold nanorods combining with the film of PMMA.And the mode fiber laser operate stably based on the gold nano-double cone material.The output wavelength is 1078 nm,and the maximum average power is 1.87 mW with 118 mW of the pump power,and the corresponding light conversion efficiency is 1.6%.At this time,the repetition frequency of the pulse is 30.65 MHz,the pulse width is 95.8ps,and the corresponding single pulse energy is 0.06 nJ.We achieved the mode-locked laser output with the center wavelength near 1030 nm successfully using the gold nanorods to be saturable absorber,the maximum output power is 2.13 mW,the corresponding light conversion efficiency is 1.34%,the pulse width is 20 ps,and the repetition frequency of the pulse is 27.45 MHz.The result shows that the gold nano-double cone and gold nanorods material have the excellent saturable absorption properties,we can achieve a shorter laser pulse with saturable absorber making from the gold nano-double cone and gold nanorods,which is expected to achieve a shorter pulse by optimizing the parameters of the materials.In the experiment,we found that the mode-locked laser would be instable because of thesupersaturation effect of the saturable absorber at high pump power.In addition,the gold ions will coagulate and PMMA is unstable under heating conditions.In the following work,we will try to control the temperature of the material to obtain a stable mode-locked laser,and we also intend to amplify the output light pulse as seed source to achieve power amplification.