Study On Optically Generated Microwave Technology Based On Coupled Laser

The development of photonic integration technology has pushed microwave photonics to a new era.At present,the research on microwave photonic technology is moving towards the direction of miniaturization and integration.As a kind of coupled laser,the twin-strip laser is a type of monolithically integrated laser with simple and compact structure,which integrates two lasers in parallel on the same chip.Due to the existence of optical confinement factor and small waveguide distance,lateral coupling will occur between the twin lasers,that is,leading to mutual injection.Therefore,the output light of the twin lasers will have a high correlation,which will cause a more complex dynamic process than in the case of the unidirectional optical injection in the traditional master-slave constructure.Free of any external microwave sources and modulators,high-quality microwave signal can be easily obtained by use of these nonlinear states.Optically generated microwave can be conveniently realized based on the twin-strip semiconductor laser independently.Optical frequency comb and microwave frequency comb can be obtained by adjusting the working parameters,which makes the twin-stripe semiconductor laser to be a new type of monolithically integrated microwave photonic platform.Therefore,the technology of optically generated microwave and frequency comb based on coupled semiconductor laser has very important scientific significance and application value.This thesis mainly focuses on the rich nonlinear states produced by the coupled semiconductor laser under mutual injection to generate optical and microwave signals.The main work of the thesis is as follows:1.The research progress of microwave photonics and the development of semiconductor lasers are introduced,with emphasis on the research status of optically generated microwave,frequency comb generation,and integrated semiconductor lasers.2.Based on the coupling mode theory under perturbation,the coupling intensity between the twin lasers is analyzed theoretically,and a mathematical expression of the relationship between coupling intensity and coupling distance is obtained,which provides theoretical support for studying the dynamics in integrated coupled lasers.3.Based on the technology of mutual injection,optically generated microwave is demonstrated.Various complex nonlinear states of the coupled laser are numerically simulated in two situations of symmetric and asymmetric.Microwave signals with low phase noise and high noise tolerance are obtained by beating the optical outputs from the twin lasers when they are both in the injection locking state simultaneously.4.Based on the technology of mutual injection,the schemes to generate optical and microwave frequency comb are proposed and simulated.The frequency combs are generated when the twin lasers are in the multi-period oscillation state,and the quality of the generated frequency combs can be improved by employing external RF signals at low frequencies to directly modulate both the twin lasers.In addition,the effects of bias currents and modulation frequencies on the generated frequency combs are also investigated.In this context,a monolithically integrated multi-function platform that combines optically generation of microwave,optical frequency comb,and microwave frequency comb is verified and fulfilled.