Research On The Theories And Experiments Of Microresonator-based Optical Frequency Combs

Optical frequency comb is a unique laser source,whose spectrum consists of a series of strictly equidistant spectral lines.It plays an important role in the fields of high-precision time-frequency measurement,large-capacity optical communication,microwave photonics and spectroscopy.In recent years,Kerr frequency combs based on third-order nonlinear microresonator have attracted a lot of researchers' interest.A large number of frequency lines of combs are generated by the cascaded four-wave mixing in the Kerr microresonator.Compared with the traditional modelocked lasers,the microresonator-based Kerr frequency combs have the advantages of high repetition rate,low power consumption,high integration and low cost.Although the development of the microresonator-based Kerr frequency combs has been mature abroad,there are still some problems.Recently,more and more attention has been paid to the second-order nonlinear microresonator-based frequency combs,which are also called quadratic frequency combs,because they can not only generate the comb near the pump frequency,but also in the band where Kerr frequency combs are difficult to generate,leading to the formation of dual-combs,and at the same time,they have a low pump power threshold.At present,the research of quadratic frequency combs is not mature,and there is a huge development space.In this thesis,firstly,the theoretical models based on Kerr microresonators are established,and the algorithm design and simulation analysis are carried out.The dynamic process of the microresonator-based Kerr frequency combs is analyzed by the simulation.Secondly,aiming at the problems such as the uncertain number of solitons and the huge power drop,the corresponding solution models are established.Finally,the experimental platform of the microresonator-based Kerr frequency combs is built,and the Kerr frequency combs with the repetition rate of 100 GHz is successfully generated.For the microresonator-based quadratic frequency combs,on the one hand,we simulated and realized the soliton dual-combs based on the second harmonic generation.Aiming at the problem of the uncertain number of solitons and the low pump efficiency,we proposed a new scheme of using the synchronous pulse pump,which can make the system generate the singlesoliton deterministically and greatly improve the pump efficiency.On the other hand,in the simulation,we found the new phenomenon of the soliton in the second-order nonlinear optical parametric oscillator,and the existence region of the soliton is analyzed.The influence of the parameters on the soliton is deeply investigated.This work has a significant predictive impact on the experiments in future.