Study On The Mechanism Of Second Harmonic Generation In Optical Microcavity

The optical microcavity platform based on whispering-gallery mode can regulate information in environmental monitoring,biochemistry,medical diagnosis and other aspects.The platform has the characteristics of easy integration,small mode volume and high quality factor.It is widely used in the fields of classical nonlinear optics,microwave and quantum photonics.Controlling the generation of the second harmonic in the micro-ring resonator has an important influence on industrial measurement,microscopy imaging and two-dimensional material structure characterization.It has attracted more and more researchers’attention.Improving the conversion efficiency of the second harmonic has become a research hotspot.Parity time symmetric resonators have attracted extensive research due to their good transmission performance and the special properties of the system at exceptional points,and have important applications in the fields of cavity optomechanical system,optical solitons and so on.Taking the microring resonator as the research model,this paper focuses on the generation mechanism of the second harmonic and the special phenomenon of the conversion efficiency of the second harmonic at the exceptional points.The main contents are as follows:1.A parity time symmetric optical dimer system composed of gain microring resonator and dissipation microring resonator is constructed.The eigenvalues of the system and the conversion efficiency of the second harmonic generation of the system are calculated.The total loss rate of the gain microring resonator and the coupling strength between the gain microring resonator and the dissipation microring resonator are adjusted respectively.It is obtained that the system has two exceptional points in two cases.The characteristics of eigenvalues are observed through simulation.2.It is found that the conversion efficiency of second harmonic generation can reach the maximum at the exceptional points in both cases,and the maximum conversion efficiency is 6.05 × 1022,which greatly improves the conversion efficiency of second harmonic generation.This paper theoretically proves that the system can improve the conversion efficiency of second harmonic generation,and provides a new research idea for regulating second harmonic generation.