Research On Nonlinear Effects In High Q Microsphere Resonator

In an optical resonator with whispering gallery mode,photons are continuously reflected along the inner wall of the resonator to form a resonant mode.Because of its low loss,small mode size and easy integration,the resonator with high quality factor can obviously enhance the interaction between matter and photons.When the low-power pump light is used as the input light source,the pump light meets the resonant conditions in the resonator can circulate along the resonator,which makes the energy density in the resonator is extremely large and greatly reduces the threshold of the nonlinear effect in the resonator.It has great potential in the application of non-linear photonics,cavity quantum electrodynamics,micro-sensors and so on.In this paper,high quality factor microsphere cavity is selected as the research object,and tapered fiber as the coupler.The generation principle and mechanism of the nonlinear optical characteristics are discussed by combining simulation with experiment.The fabrication process and parameter matching of the microsphere cavity and tapered fiber,the conditions of high efficiency coupling between tapered fiber and tapered fiber microsphere cavity are analyzed in detail.The main work is as follows:1.With a thorough understanding of the performance parameters of the microsphere cavity and its nonlinear effects,the principle and mechanism of the generation of nonlinear optical effects are elaborated,including Brillouin effect,Raman effect and Kerr nonlinear effect.The thermal dynamic process accompanied by nonlinear effects in the microsphere cavity is analyzed in detail,and the influence of thermal effects is quantitatively analyzed in LLE.By introducing the effect of thermal effect,the simulation results are further consistent with the experimental results.2.Using LLE equation after introducing thermal effect,according to the basic parameters of the microsphere cavity obtained from the experiment,the parameters needed for simulation are calculated.The evolution process of the nonlinear characteristics in the microsphere cavity is simulated and analyzed,and the influencing factors of the nonlinear effect in the cavity,including detuning value,pump power and the number of dissipative cavity solitons,are studied in theory.In addition,the stability and flatness of the optical frequency comb produced by the nonlinear effect under the influence of thermal effect are analyzed,which can make the optical frequency comb have better application space.3.The fabrication process of microsphere cavity and tapered fiber is described in detail.The parameter matching problem of microsphere and tapered fiber system and the influencing factors of high efficiency coupling are analyzed.A high Q microsphere cavity with a quality factor of 5.2*10~8 is fabricated experimentally.At the same time,the nonlinear characteristics of the microsphere cavity are verified experimentally.The cascaded Brillouin effect of order 6 was observed.The dependence of input power on Stokes signal light produced by Brillouin effect was analyzed.The signal-to-noise ratio of Stokes signal light was optimized.