Fabrication Of Open Microcavities And Coupling With Quantum Dots

There are many types of optical microcavity structures,among which Fabry-Perot(F-P for short)cavity is the most basic structure and is the earliest to be made and studied.The unique characteristic of this structure is that the cavity length is continuously adjustable and the material is easy to be placed in the cavity,so it is convenient to make an open microcavity and study its interaction with quantum dots(QDs for short).In the study of the interaction with QDs,the Purcell effect and the vacuum Rabbi splitting were found through weak coupling and strong coupling respectively.In previous research of F-P cavity coupling with QDs,self-organized QDs are mostly used,which are grown together with the cavity mirrors.The compatibility of this structure is not good enough,and the process of fabricating this structure is complicated.The structure of F-P cavity presented by this article is completely open and colloidal QDs are used.The cavity mirrors can be isolated from the QDs,which are put into the cavity by spin coating.In this paper,the colloidal perovskite QDs are used,whose coupling with the optical cavity has not been reported yet.Starting from the basic F-P cavity structure,we further discuss the fundamental principles of reflection and transmission for calculating the quality factor Q and photon life time τ of the cavity mode,and also prove that the higher the reflectivity of cavity mirrors the greater the Q value is.We then introduce the transfer matrix method,which is used through MATLAB to calculate and simulate the optical field distributions in distributed Bragg reflector(DBR for short)and microcavity consisted of DBR cavity mirrors.This method proves that the larger refractive index difference of the materials constituting the DBR and more numbers of the DBR layers would lead to a greater reflectivity of the DBR.Next the structure design of cavity,the manufacture of cavity mirror and the construction of the optical measuring system are described in detail.We use silica substrate with convex platform to fabricate the cavity mirror of the cavity structure.In order to decrease the difficulty of cavity adjustment and improve the Q value,we designed the concave cavity mirror,which can be controlled by the x,y,z three-axis nanopositioning stages.The transmission spectrum of cavity is measured with a peanut shaped concave cavity mirror,and the fluorescence of CsPbI3 QDs coupled with cavity mode is detected.Finally we introduce the fabrication and application of a sandwich structure microcavity that is called a planar dielectric antenna.It uses layered structure to adjust the angle of a single molecular directional emission to improve the collection efficiency of luminescence material.In the optical experiments,the enhancement of QDs’fluorescence is detected through the structure with the luminescence properties being not changed.