Research On Chaos Based On Light Injection DFB Laser

The chaotic signal has greatly improved its application scenarios because of its noise-like,wide frequency spectrum and good correlation characteristics,it has become an ideal signal in optical communications.Due to some inherent properties of semiconductor materials,semiconductor lasers are very sensitive to external disturbances,and their output signals are prone to nonlinear dynamic effects.Moreover,semiconductor lasers have some advantages,such as simple manufacturing,small size,long lasting,high electro-optical conversion efficiency,and wide wavelength coverage.It has become a good optical element for obtaining chaotic signals,so the current research on the nonlinear dynamic characteristics of semiconductor lasers has become a hot topic.In the past ten years of research,both experiments and theories have proved that by applying external disturbance to the semiconductor laser,the output signal of the semiconductor laser can show complex nonlinear dynamics,and the most commonly used methods is optical feedback,light injection and photoelectric feedback.Among which light injection,compared with the other two methods,it uses an independent laser to provide disturbance,and can control the amount of disturbance by controlling the disturbance mechanism of the injected laser,so as to control the nonlinear dynamic effect of the laser output signal to the maximum extent.Therefore,the nonlinear effect of light injected into the output signal of semiconductor lasers has become a research focus in recent years.Light injected can be simply divided into two ways:one is single light injection;the other is external light mutual injection.In this paper,relevant experimental research and theoretical simulation are carried out on these two methods respectively.Experiments have studied the nonlinear dynamics characteristics of strong light injected into semiconductor lasers,through the experimental results,it can be seen that in the case of strong light injection,the control injection intensity remains unchanged,and with the increase of the frequency detuning,the output signal of the DFB laser of the dynamic state experiences complex nonlinear dynamic states such as periodic oscillation,chaos,injected locking,single-period oscillation,period-doubling oscillation,multi-period oscillation,chaos and other complex nonlinear dynamics states.It can be seen from the experimental phenomenon that the dynamic state of the output signal of the strong light injected into the DFB laser will experience two chaoses at this time,and a broadband chaotic laser of the effective bandwidth of 32.2 GHz can be obtained;by controlling the frequency detuning amount to remain unchanged,the influence of injection intensity on the nonlinear dynamic state of the output signal in two chaotic states was explored.Through experiments,it can be seen that as the injection intensity increases,the first chaotic state entered by the output signal of DFB laser will experience the dynamic state of multi-period oscillation,chaos and injected locking.While the output signal of DFB laser enters the second chaotic state through a complete chaotic path of single period oscillation,multiple period oscillation,chaos and so on.It is of great reference value to study the nonlinear dynamic characteristics of high-light injected semiconductor lasers and to explain the physical cause of bandwidth broadening.A single chip integrated mode tunable chaotic laser based on mutual injection is simulated theoretically,the laser emits a transverse electric field fundamental mode（TE₀）or a transverse electric field first-order mode（TE₁）chaotic laser by electric tuning,and the wavelength of the laser emitted is similar,the chaotic laser of different transverse modes will not interfere with each other when propagating in the same waveguide,this can greatly improve the accuracy of space secure communication and chaotic laser ranging and expand its application scenarios.At present,there is no relevant report on monolithic integrated mode tunable chaotic laser.On the one hand,this design saves passive components such as mode converters,simplifies the complexity of the system,and completes the theoretical simulation;on the other hand,monolithic integration greatly saves production costs and is easier for practical applications.