Study On High Quality Factor Microsphere Cavity Applied To Optical Frequency Comb

Nowadays,fiber-coupled whispering gallery mode(WGM)microspheres become more and more popular because of its high quality factor(Q)and small model volume.In this paper,the coupling characteristics of WGM microsphere cavity are theoretically calculated and analyzed based on COMSOL.By finding the best coupling interval and matching size of the sphere-fiber system,and improving the structural characteristics of WGM microsphere cavity,its Q value is increased,so that it can be applied in the research of optical frequency comb.Based on the advantages of the microcavity,the Kerr optical frequency comb has also attracted the interest of many scholars,and its application fields have gradually expanded(astronomy,communications,etc.).This paper uses the Lugiato-Lefever Equation(LLE)model to explore the formation process of the optical frequency comb in the microcavity,and proposes the use of phase modulation to realize the control of the optical comb in the cold cavity.The main work is as follows:1.The theoretical model of the single microsphere-tapered fiber coupling system(SMC)is introduced.The optimal phase matching condition of the SMC coupling system is obtained by the theorefical simulation of the SMC using the COMSOL.2.The model describing the formation process of the optical comb is introduced.According to the formation process of the optical comb in the microcavity,the formation conditions of the Turing ring,breather,bright soliton,soliton molecule,dark soliton,and dark breather are discussed separately.Next,discussion will be conducted for the impact of higher order dispersion and noise on the optical comb.3.We propose the phase modulation of the cold microcavity soliton and breather soliton,and realize the conversion between the soliton state,including Turing ring,breather soliton,chaos into a single soliton.The soliton generation position can be controlled at the same time.Then,the effects of phase modulation on high-order dispersion have been studied.Finally,it is proposed to control the number of the original pulses distributed equally in the cavity.Next,the changes of the optical comb will be observed.