Studies On Fiber Based Fabry-Perot Microcavities For Single-photon Sources

Recently,with the development of quantum optics,more and more applications emerge in the quantum fields,such as quantum measurement,quantum communication,and quantum information.Therefore,researchers start to focus on the studies on quantum sources,the fundamental block of quantum optics,pursuing high purity bright and deterministic single-photon sources.In order to achieve this goal,optical mirocavity comes out.Optical microcavity with small mode volume and high Q value is able to enhance the light-matter interaction due to strong light confinement,which can increase the spontaneous emission of dipole and the coupling efficiency of radiation mode to cavity mode.Combine with optical microcavity,it is feasibility to achieve bright and efficient single-photon sources.Current researches mainly focus on single-photon sources based on photonic-crystal nanocavity or micropillar with the advantage of on-chip compatibility but with the limit of adjustment in space domain and Frequency domain.Compared to other microcavities,such as Photonic Crystal Cavity,Fiber based Fabry-Perot Cavity(FFPC)is open and length adjustable.And because of fiber-based structure,there is no need to couple the output light into the optical fiber system decreasing the coupling loss,making it extremely useful in the field of quantum optics.Although the fiber Fabry-Perot microcavity has many advantages,the current fabrication technology based on the fiber Fabry-Perot microcavity has its own shortcomings.For example,the processing cost of focused ion beam etching is too high,and for the CO2 laser ablation,due to the diffraction limit of the spot,it is often difficult to process concave structures with a small radius of curvature.And because of the immaturity of the fabrication process,there are few researches on the coupling efficiency of single photon source based on fiber Fabry-Perot microcavity.However,the new microcavity fabrication technology proposed by our laboratory combines chemical etching and CO2 laser smoothing,which is expected to be able to accurately control the radius and size of the concave structure.Therefore,this article firstly demonstrates the mode coupling theory of FFPC and the parameters that may affect the coupling efficiency of FFPC(the cavity length of the FFPC and the radius of curvature of the FFPC mirror).Through numerical simulation in Chapter 3,these two parameters are optimized.The Purcell effect of the microcavity is considered to make certain correction calculations for the coupling efficiency.Under the structure of the high-Q microcavity,the total coupling efficiency can reach 93.2%,higher than the results reported in other literature.Secondly,a new microcavity fabrication scheme is proposed based on the research of our laboratory.The concave end mirror is processed by a three-step method:1)pretreatment of the fiber end face,2)core corrosion and 3)CO2 smoothing.By optimizing the entire experimental control and system,the precise control of the radius of curvature of the cavity and high repetition rate preparation has been realized.Finally,the FP microcavity was characterized by the cavity model.We realized a symmetric FP microcavity with a controllable radius of curvature,a cavity length of 3.9?m,and a mode volume of 12.5?m3,laying a good foundation for the subsequent experiments of single photon sources.Hopefully,the experimental methods and research conclusions in this article can promote the application of fiber Fabry-Perot microcavities in the field of quantum optics,and further promoting the development of quantum information and quantum computing.