Excitation,Regulation And Sensing Of Soliton Frequency Combs In Active Microsphere Cavities

Due to the structural advantages of high quality factor and low mode volume,the whispering-gallery mode microcavity greatly enhances the interaction between light and matter,which reduces the threshold of nonlinear effects in the cavity,so that the generation of optical frequency combs can be easily observed.Among them,the dissipative Kerr soliton produced by the microcavity has smooth spectrum and locked phased,and is widely applied in high-speed coherent communication,astronomical spectrometer calibration,microwave generation and other fields.Moreover,the rich sensing mechanism of the whispering gallery mode microcavity also provides a platform for ultrasensitive optical sensing.However,for the whispering gallery mode microcavity,the efficiency of generating soliton frequency combs is low and the method of all-optical regulation are lacking,so the progress on the practical road has been poor.In addition,the existing optical microcavity is not functional enough,and it is difficult to meet the needs of real environment.Under the above background,this thesis aims to make gain improvements to the traditional microsphere cavity.By combining metamaterials,gain media and microsphere cavity through advanced technology,an Er³⁺doped microsphere cavity soliton regulator and a graphene-functionalized microsphere cavity single-molecule sensor are proposed.Carry out innovative research on how to excite,regulate and apply soliton frequency combs in the improved cavity.The main work is as follows:1.The preparation technology of micro-nano fiber,the technology of preparing Er³⁺doped microsphere cavity by solution-melting method and the technology of dry transfer graphene to microsphere cavity are studied.By optimizing the preparation scheme,micro-nano fibers with a insertion loss of less than 0.2 d B were prepared,and a microsphere cavity with an Er³⁺doped concentration of the order of 10¹⁹ and a microsphere cavity with a quality factor of the order of 10~8 after graphene attachment were obtained.2.Using the LLE model,the influence of Er³⁺on the Q value,refractive index and evolution of the solitons in the cavity of the microspheres is deeply analyzed,and the principle of all-optical regulation of the solitons in the microcavity by Er³⁺is expounded.The principle of double Stoke soliton generation and sensing in the Raman gain region in the microsphere cavity is explored from the physical mechanism,and the co-locking of Kerr and Stoke soliton is simulated by the LLE model,and the microsphere is simulated by the finite element method.The effective refractive index of different modes in the cavity provides theoretical support for the beat frequency signal generated in the experiment.3.An Er³⁺doped microsphere cavity optical soliton regulator is realized,which not only realizes the increase of intracavity soliton power,the broadening of spectrum,and the increase of soliton steps from 6.2 GHz to 16 GHz,but also realizes the increase of intracavity soliton power.Fast switching regulation of reverse transmission soliton frequencies up to 7 MHz.4.Realized a graphene-functionalized microsphere cavity supersensitive sensor,and realized the recognition of NH₃,CO₂ and H₂O mixed gas molecules by photoelectric heterodyne detection and lock-in amplification technology.With concentration detection,its sensing sensitivity reaches the single molecular weight level.