Study On Polarization And Dynamical Characteristics Of Semiconductor Lasers With Optical Injection

Since 1980s, optical injected semiconductor lasers (SL) have drawn much attention. They are widely used in frequency locking, phase locking, noise reducing, modulation width enhancement, clock recovery, microwave generation and synchronized communication etc. When subjected to self-injection, such as common optical feedback (COF) and phase conjugated feedback (PCF), or subjected to unidirectional and mutual injections from outer lasers, SLs tend to show rich dynamics. A detailed study on such behaviour can help us comprehending the essence of nonlinear systems of SLs, as well as enhancing the device performances and extending applications of SLs in optical communication. Besides, as a representative type of SL, vertical-cavity surface-emitting laser (VCSEL) shows lots of merits over traditional edge-emitting lasers (EELs). However, the polarization characteristics of a VCSEL is complex due to it's special cavity configuration. The polarization degree of freedom adds more complex dynamics to optical injected VCSELs, generating new issues and applications. So this paper presents a detailed study on nonlinear dynamics and polarization characteristics of optical injected SLs. Our purpose is to expose the dynamical evolvement of SL, the law of polarization distribution and the related physical mechanism, and also to find ways of polarization dynamics control and some related applications.We develop simulation models by using multilevel masking method in Simulink. These models are found on the spin-flip mode, the rate equations and dimensioness method. In the analysis, steady state analysis, dynamical bifurcation and small perturbation theory are used; besides, bifurcation diagram, spectrum, eyediagram, track of phase space, mapping of parameter space, and correlation curve are taken as references to character output's physical characteristics. The main contents and results of this thesis are:The bifurcation behaviors, symmetry of the time serial of optical filed and noise characteristics for EELs are analyzed, taking multiple feedback and response time of phase conjugate mirror in to consideration. The result show, multiple feedbacks will advance the bifurcation, or change the ranges of multiple period and chaotic states; optical field under multiple PCF is no longer symmetrical when rotated byπ; long response time of phase conjugate mirror suppresses nonlinearity and relative intensity noise. In addition, PCF can also be used in optical chaos communication as to reduce the dispersion and nonlinearity of the fibers.Novel ideas of asymmetrical mutual injection and multiplex injection are used for the first time to realize synchronized chaotic communication; the former are also extended for the use of one-to-many and many-to-one optical network communication. By using asymmetrical mutual injection, the disadvantage of temporary synchronization in traditional mutual injection system is overcome, and chaos-pass-filtering effect is shown in both directions, so we can communicate bidirectionally. By using multiplex injection introduced by an intermediary, the disadvantages, that encoding reduces synchronization degree and message frequency is constrained by chaos-pass-filtering, are avoided.The dynamics and polarization characteristics of mutually coupled VCSELs are investigated detailedly. In addition, the ways of using asymmetric mutual injection to control dynamics and polarization of VCSELs are discussed. Under polarization parallel mutual injection, the two VCSELs show similar characteristics as they were subjected to optical feedback. Under polarization orthogonal mutual injection, the two VCSELs show different polarization switching (PS) characteristics due to frequency detuning. Taking x-polaized mode orthogonal injection as an example, we find that there exists an asymmetrical region wherein the two VCSELs emit x-polarized and y-polaized mode respectively, and mutual injection turns into undirectional injection. Under certain parameter conditions, the compound mode of VCSELs shows almost periodical mode hopping with the company of PS, which is due to the maximal-gain mode generating alternatively in the x-polarized and y-polarized directions.PS bistability of VCSELs is controlled using a novel method of time-varying orthogonal injection, and a simple theoretical model is developed to explain the influence of time-varying injection. It is found that PS is postponed by time-varying injection, and the width of PS region is broadened by a fast scanning rate. Physically, this is due to the output's memory about the former state, and it can also be well explained by the theoretical model. Furthermore, the thesis investigates, for the first time, four-wave-mixing (FWM) effect and optoelectronic feedback issue about VCSELs, taking both the linearly and elliptically polarized states into consideration. The results show, FWM of linearly polarized state is similar to that of EELs; FWM of elliptically polarized state are sensitive to anisotropy and birefringence parameters, especially, when frequency detuning is between positive and negative relaxation oscillations frequency, the regenerated and phase conjugated spectra show evident distortions. Weak optoelectronic feedback induces bifurcation of the elliptically state, and strong optoelectronic feedback adds in-phase and anti-phase fluctuations with different frequencies to the two linearly polarized states.